Conversion Tables, Formulas and Suggested Guidelines for Horticultural Use (2024)

Bulletin 931

Prepared by Bodie V. Pennisi, Gary L. Wade, Melvin P. Garber, Paul A. Thomas and James T. Midcap, Horticulture Department
Original manuscript by S.C. Myers and A.J. Lewis, former Extension horticulturists

Equivalents for liquid measure (volume)
Equivalents for dry measure and weight
Metric system conversion table
Dilution of liquid pesticides at various concentrations
Equivalent quantities of dry materials (wettable powders) for various quantities of water based on recommended pounds per 100 gallons
Equivalent quantities of liquid materials (emulsion concentrates, etc.) for various quantities of water based on pints per 100 gallons
Rate of application equivalent table
Fertilizer conversions for specified square feet and row areas
Fertilizer weight as measured by standard pot size
Element concentrations for pounds soluble fertilizer in 1000 gallons (U.S.) water
Injection ratios and nitrogen concentrations for constant fertilization
Injector calibration with a conductivity meter
Parts per million of desired nutrient to ounces of fertilizer carrier in 100 gallons of water (or grams in 1 liter) and vice versa
Conversion factors among electrical conductivity (EC) units
Various acids to add to irrigation water for acidification
Amounts of nutrient sources to combine in making various fertilizer formulas
Formulas for additional fertilizer calculations
Miscellaneous conversions used in fertilizer calculations
Osmocote® controlled-release fertilizers and their release periods
Rates in lb/yd3 (kg/m3) for incorporation of three of the most popular formulations of Nutricote into greenhouse root substrates
Materials, rates necessary to lower the pH level of greenhouse potting substrate 0.5 to 1.0 units
Approximate amount of materials required to change pH of potting mixes
Dilution/conversion chart for various chemical growth regulators
Pre-plant fertilizer sources and rates of application
Cornell Peat-lite Mix A for seedlings, bedding plants and potted plants
Number of pots per bushel and per cubic yard of soil mix
Number of nursery containers that can be filled from 1 yd3 of soil mix
Coverage estimates for perlite, peat, topsoil and straw
Plant spacing guide (greenhouse)
Plant spacing guide (field/orchard)
Estimated number of plants to fill 100 ft2 bed area for square (row) and triangular (equilateral) planting patterns using 4 to 14 inch spacing distances
Number of bedding/groundcover plants required at various spacing for landscape planting
Number of plants per acre at various spacings
Times required to mow or trim lawn areas
Volume of water delivered - by size of hose
Cubic yards of soil needed at various depths and areas
Areas covered in square feet at various depths
Temperature conversion
Formulas for calculating greenhouse volume
Formulas for calculating variously shaped areas

Pesticide and fertilizer recommendations often are made on a pounds-per-acre or tons-per-acre basis for field production. However, greenhouse and nursery operators, landscape professionals and orchardists often must convert these recommendations to smaller areas, such as row feet or square feet per tree or per pot. Pints, cups, ounces, tablespoons and teaspoons often are the common units of measure. Metric units of measure can further complicate conversion.

This publication is designed to help growers make these calculations and conversions and to provide other data useful in the management, planning and operation of horticultural enterprises. A number of formulas for calculating fertilizer application rates on a parts-per-million basis are given. Tables for fertilizer injector calibration using a conductivity meter, as well as pre-plant application rates for various soil mix components and amendments, also are provided. A brief explanation of how each table is used is provided.

Tables 1 through 3 help determine equivalent measures for liquid (volume) or dry (weight) chemical substances and also converting metric to English units.

Table 1. Equivalents for liquid measure (volume)
Units of Measure
Gallons (gal)	Quarts (qt)	Pints (pt)	Fluid Ounces (fl oz)	Cups	Tablespoons (tbs)	Teaspoons (tsp)	Milliliters (ml)	Cubic Centimeters (cc)	Liters (l)
1	4	8	128	16	—	—	—	—	—
—	1	2	32	4	—	—	—	—	—
—	—	1	16	2	32	—	—	—	—
—	—	—	1	1/8	2	6	30	—	—
—	—	—	—	1	16	48	240	—	—
—	—	—	—	—	1	3	15	—	—
—	—	—	—	—	—	1	5	—	—
—	—	—	—	—	—	—	1	1	—
—	—	—	—	—	—	—	1000	1000	1

Table 2. Equivalents for dry measure and weight
Dry Measure
3 level teaspoonfuls 16 level tablespoonfuls 2 cupfuls 2 pints	= = = =	1 level tablespoonful 1 cupful 1 pint 1 quart
Weight
Pounds/Ounces	to	Metric
220.46 pounds 100 pounds 2.204 pounds 1.102 pounds 1 pound/16 ounces 8 ounces 4 ounces 3.527 ounces 2 ounces 1 ounce 3/4 ounce 1/2 ounce 1/4 ounce 1/8 ounce 1/16 ounce 1/32 ounce 1/64 ounce 1/128 ounce	= = = = = = = = = = = = = = = = = =	100 kilograms (kg) 45.349 kilograms 1 kilogram 500 grams (g) 453.5900 grams 226.78 grams 113.39 grams 110 grams 56.70 grams 28.35 grams 21.25 grams 14.17 grams 7.08 grams 3.54 grams 1.77 grams 885 milligrams 442 milligrams 221 milligrams
Ounces	to	Grams
3/8 1/2 5/8 3/4 7/8 1 2 1/256 1/128 1/64 1/32 1/16 1/8 1/4	= = = = = = = = = = = = = =	10.631 14.75 17.718 21.162 24.805 28.349 56.698 0.111 0.221 0.443 0.886 1.772 3.544 7.087

Table 3. Metric system conversion table
Liquid capacity
1 fluid ounce (fl oz) 1 pint (pt) = 16 fl oz 1 quart (qt) 1 gal (gal) 1 liter (l) 1 milliliter (ml)	= = = = = =	30 milliliters (ml) 473 ml 946 ml 3,785 ml 1,000 ml 1 cubic centimeter (cc)
Dry material weight
1 ounce (avoirdupois) 1 pound (lb) 1 kilogram (kg)	= = =	28.4 grams (g) 453.6 g 1,000 g = 2.2 lb
Volume
1 cubic inch (in³) 1 cubic foot (ft³) 1 bushel (bu) 1 cubic yard (yd³)	= = = =	16.4 milliliters (ml) 7.48 gal = 28.3 liters (l) 1.24 ft³ = 35.2 liters 21.7 bu = 765 liters
Linear
1 inch (in) 1 foot (ft) 1 yard (yd) 1 meter (m)	= = = =	2.54 centimeters (cm) 30.48 cm 91.44 cm 100 cm
Area
1 square inch (in²) 1 square foot (ft²) 1 square yard (yd²) 1 acre (a) 1 square mile (M²)	= = = = =	6.45 square centimeters (cm²) 0.09 square meter (m²) 0.84 square meter (m²) 0.40 hectare (ha) 2.59 square kilometer (km²)

Tables 4 through 7 help determine correct application rates for various pesticides.

Table 4. Dilution of liquid pesticides at various concentrations
Dilution	Amount Desired
Dilution	1 Gal	3 Gal	5 Gal	15 Gal
1:100	2 tbs + 2 tsp	1/2 cup	3/4 cup + 5 tsp	1 cup + 3 tbs
1:200	4 tsp	1/4 cup	6½ tbs	1/2 cup + 2 tbs
1:400	2 tsp	2 tbs	3 tbs	4 tbs + 2½ tsp
1:800	1 tsp	1 tbs	1 tbs + 2 tsp	3 tbs + 2½ tsp
1:1000	3/4 tsp	2¼ tsp	1 tbs + 1 tsp	1 pt + 1/2 cup
Example: Directions call for a 1:200 dilution. To prepare 3 gal of finished product, you would need to add 1/4 cup.

Table 5. Equivalent quantities of dry materials (wettable powders) for various quantities of water based on recommended pounds per 100 gallons
Water	Recommended Rates
100 gal	1 lb	2 lb	3 lb	4 lb	5 lb	6 lb
50 gal	1/2 lb	1 lb	1½ lb	2 lb	2½ lb	3 lb
25 gal	4 oz	8 oz	12 oz	1 lb	1¼ lb	1½ lb
12.5 gal	2 oz	4 oz	6 oz	8 oz	10 oz	3/4 lb
5 gal	3 tbs	1½ oz	2½ oz	3¼ oz	4 oz	5 oz
1 gal	1 tsp	2 tsp	1 tbs	4 tsp	5 tsp	2 tbs
Example: Directions for use specify a rate of 4 lb per 100 gal water. To prepare 1 gal of solution would require 4 tsp of material.

Table 6. Equivalent quantities of liquid materials (emulsion concentrates, etc.) for various quantities of water based on pints per 100 gallons
Water	Recommended Rates
100gal	1/2 pt	1 pt	2 pt	3 pt	4 pt	5 pt
50 gal	4 fl oz	8 fl oz	1 pt	1½ pt	2 pt	2½ pt
25 gal	2 fl oz	4 fl oz	8 fl oz	12 fl oz	1 pt	1¼ pt
12.5 gal	1 fl oz	2 fl oz	4 fl oz	6 fl oz	8 fl oz	10 fl oz
5 gal	1 tbs	1 fl oz	2 fl oz	2½ fl oz	3 fl oz	4 fl oz
1 gal	1/2 tsp	1 tsp	2 tsp	3 tsp	4 tsp	5 tsp
Example: Directions for use specify a rate of 4 pt per 100 gal water. To prepare 5 gal of solution would require 3 fl oz material.

Table 7. Rate of application equivalent table
Rate per Acre	Rate per 1000 sq ft	Rate per 100 sq ft
Liquid Materials
1 pt	3/4 tbs	1/4 tsp
1 qt	1½ tbs	1/2 tsp
1 gal	6 tbs	2 tsp
25 gal	4⅔ pt	1/2 pt
50 gal	4⅔ qt	1 pt
100 gal	2⅓ gal	1 qt
200 gal	4⅔ gal	2 qt
300 gal	7 gal	3 qt
400 gal	9¼ gal	1 gal
500 gal	11½ gal	1¼ gal
Dry Materials
1 lb	2½ tsp	1/4 tsp
3 lb	2¼ tbs	3/4 tsp
4 lb	3 tbs	1 tsp
5 lb	4 tbs	1¼ tsp
10 lb	1/2 cup	2 tsp
100 lb	2⅔ lb	1/4 lb
200 lb	4⅔ lb	1/2 lb
300 lb	7 lb	3/4 lb
400 lb	9¼ lb	1 lb
500 lb	11½ lb	1¼ lb
*Examples:* For liquid materials, 100 gal per acre is equivalent to 2⅓ gal per 1000 ft² or 1 qt per 100 ft². For dry materials, 4 lb per acre is equivalent to 3 tbs per 1000 ft² or 1 tsp per 100 ft².

Tables 8 through 9 help determine the correct application rates for fertilizers when nutrition recommendations are based on fertilizer weight.

Table 8. Fertilizer conversions for specified square feet and row area
Material grouped by approximate weight per pint	Recommended rate per acre*	Fertilizer Rate for Specific Areas
		100 sq ft	1000 sq ft	10 sq ft	100 sq ft	Per 10 feet of row spaced**
		100 sq ft	1000 sq ft	10 sq ft	100 sq ft	1 ft	2 ft	3 ft
	lb	lb	lb	tbs	pt	tbs	tbs	cup
10 oz per pint
Sulfur or Dried Blood	100	0.2	2.3	1.2	0.4	1.2	2.4	0.2
	500	1.2	11.5	6.0	1.9	6.0	12.0	1.1
	1000	2.3	23.0	12.0	3.7	—	—	—
13 oz per pint
Urea or Ammonium Nitrate or Ammonium Chloride	100	0.2	2.3	0.9	0.3	0.9	1.8	0.2
	500	1.2	11.5	4.5	1.4	4.5	9.0	0.8
	1000	2.3	23.0	9.0	2.8	—	—	—
16 oz per pint
Ammonium Phosphate or Potassium Chloride or Gypsum or Mixed Fertilizers	100	0.2	2.3	0.7	0.2	0.7	1.4	0.1
	500	1.2	11.5	3.5	1.2	3.5	7.0	0.7
	1000	2.3	23.0	7.0	2.3	—	—	—
19 oz per pint
Calcium Nitrate or Ammonium Sulfate or Superphosphate	100	0.2	2.3	0.6	0.2	0.6	1.2	0.1
	500	1.2	11.5	3.0	1.0	3.0	6.0	0.6
	1000	2.3	23.0	6.0	2.0	—	—	—
23 oz per pint
Ground limestone or Potassium sulfatex	100	0.2	2.3	0.5	0.2	0.5	1.0	0.1
	500	1.2	11.5	2.5	0.8	2.5	5.0	0.5
	1000	2.3	23.0	5.0	1.6	—	—	—
	2000	4.6	46.0	10.0	3.2	—	—	—
* Any of the materials listed in the first column can be used at the rates shown below. High Rates, not desirable in row fertilization, are omitted in the table. Example:** You wish to apply calcium nitrate at the rate of 500 lbs per acre. It weighs approximately 19 oz per pt. For application to 100 ft², you need 1.2 lb or 1.0 pt.

Table 9. Fertilizer weight as measured by standard pot size
Fertilizer	Pot Size
Fertilizer	2¼"	3"	3½"	4"	5"	6"
Ammonium nitrate	2 oz	5½ oz	9 oz	15 oz	1 lb 12 oz	2 lb 15 oz
Urea, 45-0-0	2½ oz	6 oz	9 oz	1 lb	1 lb 13 oz	3 lb
Superphosphate	2½ oz	6 oz	9½ oz	1 lb	1 lb 14 oz	3 lb 2 oz
Dusting sulfur	2½ oz	6 oz	10 oz	1 lb	1 lb 14 oz	3 lb 3 oz
Peters, 20-5-30	2½ oz	6 oz	10 oz	1 lb 1 oz	1 lb 15 oz	3 lb 3 oz
Ammonium sulfate	3 oz	7 oz	11 oz	1 lb 3 oz	2 lb 3 oz	3 lb 11 oz
Osmocote, 14-14-14	3 oz	7½ oz	12 oz	1 lb 4 oz	2 lb 5 oz	3 lb 13 oz
MagAmp, 12-62-0	3 oz	7½ oz	12 oz	1 lb 4 oz	2 lb 5 oz	3 lb 14 oz
Gypsum, CaSO₄	3 oz	8 oz	12½ oz	1 lb 5 oz	2 lb 7 oz	4 lb 1 oz
Calcium nitrate	3 oz	8 oz	12½ oz	1 lb 6 oz	2 lb 8 oz	4 lb 2 oz
Peters, 15-0-15	3½ oz	8 oz	13 oz	1 lb 6 oz	2 lb 9 oz	4 lb 5 oz
Potassium chloride	3½ oz	9 oz	14 oz	1 lb 8 oz	1 lb 12 oz	4 lb 9 oz
Sodium nitrate	4 oz	9 oz	15 oz	1 lb 9 oz	2 lb 14 oz	4 lb 13 oz
Dolomitic limestone	5½ oz	13 oz	1 lb 5 oz	2 lb 4 oz	4 lb 2 oz	6 lb 14 oz
Clay flower pots are frequently used for fertilizer measurement by greenhouse operators. The above shows average weights of several representative fertilizers as measured by standard clay pots when level full. The 3-inch standard is considered to contain 8 fl oz or 1 cup. Since the actual pot size varies with the manufacturer and the volume of a given weight of fertilizer varies with moisture and compaction, deviations of 10 percent may be expected but up to 40 percent may occur.

Tables 10 through 14 help determine the correct application rates for fertilizers with various analysis when nutrition recommendations are based on parts per million and fertilizer injectors are used to deliver liquid plant fertilizer. Table 12 is designed to help growers calibrate their injectors.

Table 10. Element concentrations for pounds soluble fertilizer in 1000 gal (U.S.) water
Desired PPM	Pounds of Fertilizer Needed
	% Nitrogen (N)					% Phosphate (P₂O₅)				% Potash (K₂O)
	30	25	20	15	10	20	15	10	5	25	20	15	10
300	8.3	10.0	12.5	16.7	23.0	—	—	—	—	12.0	15.0	20.0	30.0
275	7.8	9.2	11.4	15.3	23.0	—	—	—	—	11.0	13.7	18.2	27.5
250	7.3	8.4	10.2	13.9	21.8	—	—	—	—	10.0	12.5	16.7	26.2
225	6.2	7.5	9.3	12.5	18.7	—	—	—	—	9.0	11.3	15.0	22.5
200	5.6	6.7	8.4	11.1	16.7	19.2	—	—	—	8.0	10.0	13.3	20.0
175	4.9	5.8	7.3	9.7	14.6	16.8	22.4	—	—	7.0	8.8	10.7	17.5
150	4.2	5.0	6.3	8.3	12.5	14.4	19.2	28.8	—	6.0	7.6	10.0	15.0
125	3.5	4.2	5.3	7.0	10.2	12.0	16.0	24.0	48.0	5.0	6.2	8.4	12.5
100	2.8	3.4	4.2	5.6	8.3	9.6	12.6	19.2	38.4	4.0	5.0	6.7	10.0
75	2.1	2.5	3.1	4.2	6.2	7.2	9.6	14.4	28.8	3.0	3.8	5.0	7.5
50	1.4	1.7	2.1	2.8	4.2	4.8	6.4	9.6	19.2	2.0	2.5	3.4	5.0
25	0.7	0.9	1.1	1.4	2.1	2.4	3.2	4.8	9.6	1.0	1.3	1.7	2.5
Example: You wish to apply 200 ppm N using a 20-10-20 soluble fertilizer. Reading across from 200 ppm under the 20 percent N column, you find 8.4 lb are needed for 1000 gal water. NOTES: 1 oz/2 gal is about 30 lb/1000 gal; 1 oz/3 gal is about 20 lb/1000 gal; 1 oz/5 gal is about 12 lb/1000 gal. 1 oz/gal = 7490 ppm; 1 oz/100 gal = 75 ppm. To determine Parts Per Million (ppm) of an element in a fertilizer, simply multiply the percent of that element by 75. The answer will be the ppm of the element per oz of the fertilizer in 100 gal of water. As an example, Ammonium Sulfate contains approximately 20 percent Nitrogen. 20 percent multiplied by 75 is 15, which is the ppm of Nitrogen in 1 oz of Ammonium Sulfate per 100 gal of water.

Table 11. Injection ratios and nitrogen concentrations for constant fertilization¹
Ratio	Ounces of Fertilizer per Gal Concentrate
Ratio	100 ppm N	150 ppm N	200 ppm N
30% N formula^a
1:200	13.5	20.2	27.0
1:200	9.0	13.5	18.0
1:150	6.7	10.1	13.5
1:128	5.7	8.6	11.5
1:100	4.5	6.7	9.0
1:50	2.2	3.3	4.5
1:30	13.0	2.0	2.7
1:24	1.0	1.6	2.1
1:15	0.67	1.0	1.3
25% N formula^b
1:300	16.5	24.7	33.0
1:200	11.0	16.5	22.0
1:150	8.2	12.3	16.5
1:128	7.0	10.5	14.0
1:100	5.5	8.2	11.0
1:50	2.7	4.1	5.5
1:30	1.6	2.4	3.3
1:24	1.3	1.9	2.6
1:15	0.82	1.2	1.6
20% N formula^c
1:300	20.2	30.3	40.5
1:200	13.5	20.2	27.0
1:150	10.1	15.1	20.2
1:128	8.6	12.9	17.2
1:100	6.7	10.1	13.5
1:50	3.3	5.0	6.7
1:30	2.0	3.0	4.0
1:24	1.6	2.4	3.2
1:15	1.0	1.5	2.0
15% N formula^d
1:300	27.0	40.5	54.0
1:200	18.0	27.0	36.0
1:150	13.5	20.2	27.0
1:128	11.5	17.2	23.0
1:100	9.0	13.5	18.0
1:50	4.5	6.7	9.0
1:30	2.7	4.0	5.4
1:24	2.1	3.2	4.3
1:15	1.3	2.0	2.7
¹From Ball RedBook, 16th Edition, published by Ball Publishing. Reprinted with permission ^ae.g, 30-10-10 ^be.g., 25-5-20, 25-10-10, 25-0-25 ^ce.g., 20-20-20, 20-5-30, 21-7-7 ^de.g., 15-15-15, 15-30-15, 16-4-12

Table 12. Injector calibration with a conductivity meter¹
*A. Peters Single Element Fertilizer Components*
ppm Nitrogen	Ammonium Nitrate NH₄NO₃ 34% N	Ammonium Sulfate (NH₄)₂SO₄ 21% N	Sodium Nitrate NaNO₃ 16% N	Potassium Nitrate KNO₃ 14% N	Calcium Nitrate Ca(NO₃)₂ 15.5% N	Epsom Salt MgSO₄ 10% Mg
50	0.23	0.45	0.43	0.48	0.37	0.38
75	0.35	0.68	0.65	0.71	0.55	0.56
100	0.46	0.90	0.86	0.95	0.74	0.75
125	0.58	1.13	1.08	1.18	0.92	0.94
150	0.69	1.35	1.29	1.42	1.11	1.13
175	0.81	1.58	1.51	1.66	1.30	1.31
200	0.92	1.90	1.72	1.90	1.48	1.50
225	1.04	2.03	1.94	2.14	1.66	1.69
250	1.15	2.25	2.15	2.37	1.85	1.88
275	1.27	2.48	2.37	2.61	2.04	2.06
300	1.38	2.70	2.58	2.85	2.22	2.25
350	1.61	3.15	3.01	3.32	2.59	2.63
400	1.84	3.60	3.44	3.80	2.96	3.00
450	2.07	4.05	3.87	4.27	3.33	3.38
500	2.30	4.50	4.30	4.75	3.70	3.75
550	2.53	4.95	4.73	5.22	4.07	4.13
600	2.76	5.40	5.16	5.70	4.44	4.50
650	2.99	5.85	5.59	6.17	4.81	4.88
700	3.22	6.30	6.02	6.65	5.18	5.25
750	3.45	6.75	6.45	7.12	5.50	5.63
800	3.68	7.20	6.88	7.60	5.92	6.00
850	3.91	7.65	7.31	8.07	6.29	6.38
900	4.14	8.10	7.74	8.55	6.66	6.75
950	4.37	8.55	8.17	9.02	7.03	7.13
1000	4.60	9.00	8.60	9.50	7.40	7.50
¹Adapted from Grace Horticultural Products. W.1 R. Grace & Co. Cambridge, Massachusetts 02140. NOTES: 1) For use with meters in millimhos with Peters® Single Element Fertilizer Components. 2) These are readings made with distilled water. 3) Test your plain irrigation water first and subtract that reading from the fertilizer-injected water. For example, your water test indicates 0.5 mmhos and you are applying 500 ppm N with calcium nitrate. Your calibration reading is 3.70 - 0.5 = 3.20 mmhos.

Table 12. Injector calibration with a conductivity meter¹
*B. Peters Mixed Soluble Fertilizer Analysis*
ppm Nitrogen	20-20-20 20-19-18	20-10-15	20-5-30	25-5-20	25-10-10 30-10-10	5-11-26 Hydrosol	15-16-17 15-11-29 15-20-25
50	0.23	0.31	0.22	0.12	0.09	1.00	0.32
75	0.34	0.47	0.33	0.18	0.14	1.50	0.48
100	0.45	0.62	0.44	0.24	0.18	2.00	0.65
125	0.56	0.78	0.56	0.30	0.23	2.50	0.82
150	0.68	0.93	0.69	0.36	0.27	3.00	1.00
175	0.79	1.09	0.81	0.43	0.32	3.50	1.20
200	0.90	1.24	0.94	0.51	0.36	4.00	1.40
225	1.01	1.40	1.07	0.57	0.41	4.50	1.56
250	1.13	1.55	1.20	0.62	0.47	5.00	1.72
275	1.24	1.71	1.32	0.71	0.51	5.50	1.91
300	1.35	1.86	1.43	0.80	0.54	6.00	2.10
350	1.58	2.17	1.66	0.92	0.64	6.50	2.45
400	1.80	2.48	1.90	1.04	0.74	7.00	2.80
450	2.03	2.79	2.15	1.18	0.85	7.50	3.15
500	2.25	3.10	2.40	1.32	0.96	8.00	3.50
550	2.48	3.41	2.61	1.45	1.06	-	3.84
600	2.70	3.72	2.82	1.58	1.16	-	4.18
650	2.93	4.03	3.03	1.71	1.26	-	4.52
700	3.15	4.34	3.24	1.84	1.36	-	4.80
750	3.38	4.65	3.45	1.98	1.46	-	5.20
800	3.60	4.96	3.66	2.11	1.56	-	5.54
850	3.83	5.27	3.87	2.24	1.66	-	5.88
900	4.05	5.58	4.08	2.37	1.76	-	6.22
950	4.28	5.89	4.29	2.50	1.86	-	6.56
1000	4.50	6.20	4.5	2.63	1.96	-	6.90
¹Adapted from Grace Horticultural Products. W.1 R. Grace & Co. Cambridge, Massachusetts 02140. NOTES: 1) For use with meters in millimhos with Peters® Fertilizer formulations. 2) These readings are made with distilled water. 3) Test your plain irrigation water first and subtract that reading from the fertilizer-injected water. For example, your water test indicates 0.2 mmhos and you are applying 200 ppm N with 15-15-15 fertilizer. Your calibration reading is 1.30 - 0.2 = 1.10 mmhos.

Table 12. Injector calibration with a conductivity meter¹
*B. Peters Mixed Soluble Fertilizer Analysis (cont.)*
ppm Nitrogen	15-15-15	15-10-30	15-30-15	15-0-15	16-4-12	21-7-7 Acid	21-7-7 Neutral
50	0.30	0.32	0.31	0.36	0.32	0.28	0.21
75	0.46	0.51	0.47	0.55	0.48	0.42	0.32
100	0.62	0.70	0.62	0.74	0.64	0.56	0.42
125	0.79	0.87	0.78	0.94	0.81	0.70	0.53
150	0.96	1.50	0.93	1.15	0.98	0.84	0.63
175	1.13	1.23	1.09	1.35	1.14	0.98	0.74
200	1.30	1.41	1.24	1.55	1.31	1.12	0.84
225	1.47	1.59	1.40	1.72	1.47	1.26	0.95
250	1.65	1.78	1.55	1.90	1.62	1.40	1.05
275	1.82	1.95	1.71	2.09	1.81	1.54	1.16
300	1.98	2.12	1.86	2.28	2.00	1.68	1.26
350	2.31	2.45	2.17	2.64	2.29	1.96	1.47
400	2.65	2.78	2.48	3.00	2.58	2.24	1.68
450	2.98	3.12	2.79	3.34	2.93	2.52	1.89
500	3.25	3.46	3.10	3.68	3.28	2.80	2.10
550	3.55	3.76	3.41	3.98	3.57	3.08	2.31
600	3.85	4.06	3.72	4.28	3.86	3.36	2.52
650	4.15	4.36	4.03	4.58	4.15	3.64	2.73
700	4.45	4.66	4.34	4.88	4.44	3.92	2.94
750	4.75	4.95	4.65	5.20	4.72	4.20	3.15
800	5.05	5.25	4.96	5.50	4.98	4.48	3.36
850	5.35	5.55	5.27	5.80	5.24	4.76	3.57
900	5.65	5.85	5.58	6.10	5.50	5.04	3.78
950	5.95	6.15	5.89	6.40	5.76	5.32	3.99
1000	6.25	6.45	6.20	6.70	6.00	5.60	4.20
¹Adapted from Grace Horticultural Products. W.1 R. Grace & Co. Cambridge, Massachusetts 02140. NOTES: 1) For use with meters in millimhos with Peters® Fertilizer formulations. 2) These readings are made with distilled water. 3) Test your plain irrigation water first and subtract that reading from the fertilizer-injected water. For example, your water test indicates 0.2 mmhos and you are applying 200 ppm N with 15-15-15 fertilizer. Your calibration reading is 1.30 - 0.2 = 1.10 mmhos.

Table 13A. Parts per million of desired nutrient to ounces of fertilizer carrier in 100 gallons of water and vice versa.¹
Ounces of Fertilizer Carrier in 100 Gallons	Percentage of Desired Nutrient in Fertilizer Carrier
Ounces of Fertilizer Carrier in 100 Gallons	12	13	14	15.5	16	20	20.5	21
1	9	9.7	10.5	11.6	12.0	15.0	15.3	15.7
2	18	19.5	21.0	23.2	24.0	29.9	30.7	31.4
3	27	29.3	31.4	35.0	35.9	44.9	46.0	47.2
4	36	38.9	41.9	46.4	47.9	59.9	61.4	62.9
6	54	58.4	62.9	70.0	71.9	89.9	92.1	94.3
8	72	77.8	83.8	92.8	95.8	119.7	122.7	125.7
16	144	155.7	167.7	185.6	191.7	239.5	245.5	251.5
24	216	233.5	251.5	278.4	287.5	359.2	368.2	377.2
32	288	311.4	335.4	371.3	383.4	479.0	490.9	502.9
40	359	389.2	419.2	464.0	479.2	598.7	613.7	628.6
48	431	467.0	503.0	556.8	575.0	718.5	736.4	754.4
56	503	544.7	586.9	649.7	670.9	838.2	859.2	880.1
64	575	622.7	670.7	742.4	766.7	958.0	981.9	1005.8
¹From Nelson, P. V. 1998. Greenhouse Operations and Management, 5th ed. Published by Prentice Hall, Inc. Reprinted with permission.

Table 13A. Parts per million of desired nutrient to ounces of fertilizer carrier in 100 gallons of water and vice versa.¹ (cont)
Ounces of Fertilizer Carrier in 100 Gallons	Percentage of Desired Nutrient in Fertilizer Carrier
Ounces of Fertilizer Carrier in 100 Gallons	33	44	45	53	60	62
1	24.7	32.9	33.7	39.7	44.9	46.4
2	49.4	65.9	67.4	79.3	89.8	92.0
3	74.1	98.8	101.0	117.0	134.7	139.2
4	98.8	131.7	134.7	158.7	179.6	185.6
6	148.2	197.6	202.1	238.0	269.4	278.4
8	197.6	263.4	269.4	317.3	359.2	371.2
16	395.2	526.9	538.9	634.6	718.5	742.4
24	592.7	790.3	808.3	952.0	1077.7	1113.6
32	790.3	1053.7	1077.7	1269.3	1436.9	1484.8
40	987.9	1317.2	1347.1	1586.6	1796.2	1856.1
48	1185.5	1580.6	1616.5	1903.9	2155.4	2227.2
56	1383.0	1844.0	1886.0	2221.2	2514.6	2598.4
64	1580.6	2107.5	2155.4	2538.6	2873.9	2969.7
¹From Nelson, P. V. 1998. Greenhouse Operations and Management, 5th ed. Published by Prentice Hall, Inc. Reprinted with permission.

Table 13B. Parts per million of desired nutrient to ounces of fertilizer carrier in 100 gallons of water and vice versa.¹
Grams of Fertilizer Carrier in 1 Liter	PPM of Desired Nutrient in Fertilizer Carrier
Grams of Fertilizer Carrier in 1 Liter	12	13	14	15.5	16	20	20.5	21
0.1	12	13	14	16	16	20	20.5	21
0.2	24	26	28	31	3	40	41.0	42
0.3	36	39	42	47	48	60	61.5	63
0.4	48	52	56	62	64	80	82.0	84
0.6	72	78	84	93	96	120	123.0	126
0.8	96	104	112	124	128	160	164.0	168
1.0	120	130	140	155	160	200	205.0	210
1.5	180	195	210	233	240	300	307.0	315
2.0	240	260	280	310	320	400	410.0	420
2.5	300	325	350	388	400	500	512.5	525
3.0	360	390	420	465	480	600	615.0	630
3.5	420	455	490	543	560	700	717.5	735
4.0	480	520	560	620	640	800	820.0	840
¹From Nelson, P. V. 1998. Greenhouse Operations and Management, 5th ed. Published by Prentice Hall, Inc. Reprinted with permission.

Table 13B. Parts per million of desired nutrient to grams of fertilizer carrier in 1 liter water and vice versa.¹ (cont)
Grams of Fertilizer Carrier in 1 Liter	PPM of Desired Nutrient in Fertilizer Carrier
Grams of Fertilizer Carrier in 1 Liter	33	44	45	53	60	62
0.1	33	44	45	53	60	62
0.2	66	88	90	106	120	124
0.3	99	132	135	159	180	186
0.4	132	176	180	212	240	248
0.6	198	264	270	318	360	372
0.8	264	352	360	424	480	496
1.0	330	440	450	530	600	620
1.5	495	660	675	795	900	930
2.0	660	880	900	1060	1200	1240
2.5	825	1100	1125	1325	1500	1550
3.0	990	1320	1350	1590	1800	1860
3.5	1155	1540	1575	1855	2100	2170
4.0	1320	1760	1800	2120	2400	2480
¹From Nelson, P. V. 1998. Greenhouse Operations and Management, 5th ed. Published by Prentice Hall, Inc. Reprinted with permission.

Table 14. Conversion factors among electrical conductivity (EC) units.¹
From	To	Multiply by:
mmhos/cm or mS/cm or dS/cm	mhos x 10^-5/cm	100
mhos x 10^-5/cm	mmhos/cm or mS/cm or dS/cm	0.01
mmhos/cm or mS/cm or dS/cm	µmhos or mhos x 10^-6	1000
µmhos or mhos x 10^-6	mmhos/cm or mS/cm or dS/cm	0.001
mmhos/cm or mS/cm or dS/cm	ppm	670²
ppm	mmhos/cm or mS/cm or dS/cm	0.0014925²
mhos x 10^-5/cm	ppm	6.70²
ppm	mhos x 10^-5/cm	0.14925²
µmhos or mhos x 10^-6	ppm	0.6702²
ppm	µmhos or mhos x 10^-6	1.4925²
¹ Adapted from T. J. Cavins, et al., 2000. ² Some labs report EC in terms of ppm or convert EC to ppm. Although 670 is the basis used in this example, the conversion factor can vary between 640 and 700. This conversion factor is an average due to the variability in the type of fertilizer salts that contribute to the substrate EC in each sample, and it should be considered a broad approximation. Expressing EC in terms of mS/cm or mhos/cm is the preferred method.

Table 15 is designed to help growers decide which acid to add and in what quantities to acidify their irrigation water.

Table 15. Various acids to add to irrigation water for acidification.
Note: The table is an example from a website called AlkCalc, available at https://e-gro.org/alkcalc/dist/index.html. It is an acidification analysis done on a water sample with a starting pH of 8.0 and alkalinity of 200 ppm CaCO₃ acidified to an end point pH of 5.8. For your specific water sample, follow the directions on the website. You will need to obtain a water report on your irrigation water prior to using AlkCalc. You will need to know the water pH and alkalinity of your sample and have an idea about what end-point pH you want to obtain after acidification. The wesbite also gives you information about the cost of the acidification treatment.
ALTERNATIVE ACIDS TO ADD TO IRRIGATION WATER
Amounts	Acids
Amounts	Phosphoric Acid (75%)	Phosphoric Acid (85%)	Sulfuric Acid (35%)	Sulfuric Acid (93%)	Nitric Acid (61.4%)	Nitric Acid (67%)
*For Small Volumes*
ml per liter	0.253	0.207	0.348	0.087	0.234	0.209
fl oz per gallon	0.032	0.027	0.044	0.011	0.030	0.027
ml per gallon	0.956	0.785	1.316	0.330	0.884	0.793
*For a 1:100 Injector*
fl oz per gallon (conc.)	3.23	2.65	4.45	1.12	2.99	2.68
ml per gallon (conc.)	95.63	78.47	131.59	32.98	88.40	79.28
*For a 1:128 Injector*
fl oz per gallon (conc.)	4.14	3.40	5.70	1.43	3.83	3.43
ml per gallon (conc.)	122.41	100.44	168.44	42.22	113.16	101.48
*For a 1:200 Injector*
fl oz per gallon (conc.)	6.47	5.31	8.90	2.23	5.98	5.36
ml per gallon (conc.)	191.27	156.94	263.19	65.97	176.81	158.56
NUTRIENTS ADDED BY EACH TYPE OF ACID
Nutrients Added	Phosphorus	Phosphorus	Sulfur	Sulfur	Nitrogen	Nitrogen
Amount Added (ppm)	94.6	94.6	50.3	50.3	43.7	43.7
Use the information above for modifying your fertility program.

Tables 16 through 20 help determine which fertilizers to use based on chemical analysis, reaction in substrate, longevity in substrate (slow release fertilizers), and incorporation rates for some popular slow release fertilizers. Tables 17 and 18 are specifically designed to provide detailed information on fertilizer calculations, which also aid determine correct application rates.

Table 16. Amounts of nutrient sources to combine in making various fertilizer formulas¹
Fertilizer Name	Nutrient Sources²
Fertilizer Name	Analysis	33 -0 -0	13 -0 -44	15.5 -0 -0	16 -0 -0	21 -0 -0	45 -0 -0	0 -0 -60	12 -62 -0	21 -53 -0	% of N as NH₄ + Urea	Reaction in Substrate⁴
Ammonium nitrate	33-0-0	X									50	A
Potassium nitrate	13-0-44		X								0	N
Calcium nitrate	15.5-0-0			X							6	B
Sodium nitrate	16-0-0				X						0	B
Ammonium sulfate	21-0-0					X					100	A
Urea	45-0-0						X				100	SA
Potassium chloride	0-0-60							X			-	N
Monoammonium phosphate	12-62-0								X		100	A
Diammonium phosphate³	21-53-0									X	100	SA
Magnesium nitrate	10-0-0										0	B
Chrysanthemum green	18-0-22	1	2			1					47	A
General Summer	20-10-24	1					1	2		1	83	A
General low phosphate	21-4-20	7						4		1	55	A
General summer	21-17-20	1					2	3		3	90	A
General	17-6-27	4						4		1	57	A
UConn Mix	19-5-24		6	2			2		1		49	N
Editor's favorite	20-5-30		13				4			2	57	SA
20-20-20 substitute	20-20-22		4				1			3	67	SA
Starter and pink hydrangea	12-41-15		1						2		65	SA
Starter and pink hydrangea	17-35-16						1	4		10	100	SA
N-K only	16-0-24	2			1			2			40	SA
N-K only	20-0-30	1	2								28	SA
Blue hydrangea	13-0-22					2		1			100	VA
Blue hydrangea	15-0-15					3		1			100	VA
Acid	21-9-9	3	1			7		1		2	79	VA
Spring carnation	10-0-17				5			2			0	B
Winter nitrate	15-0-15		1	2							5	B
Winter potash	15-0-22		1	1							4	B
Lily substitute	16-4-12	1	4	6						1	22	N
High K	15-10-30		7	1						2	28	N
¹From Nelson, P.V. 1998. Greenhouse Operations and Management, 5th ed. Published by Prentice Hall, Inc. Reprinted with permission. ²For names of nutrient sources, see the first nine entries in the Name column. ³Diammonium phosphate may be pelletized and coated. To dissolve, use very hot water and stir vigorously. Sediment formation should not cause concern. Use crystalline potassium chloride if possible. ⁴B = basic; N = neutral; SA = slightly acid; A = acid; VA = very acid. NOTE: For example, an 18-0-22 formula fertilizer can be formulated by blending together 1 lb of ammonium nitrate plus 2 lbs of potassium nitrate plus 1 lb of ammonium sulfate. This formulation is determined by locating the 18-0-22 formula in the Analysis column. Then the three numbers 1, 2 and 1 are located in the row after this formula. Each of the three numbers is traced to the X above it and then to the nutrient source to the left of the X.

Table 17. Formulas for additional fertilizer calculations
Compound	Formula	Weight
Ammonium Nitrate Ammonium Sulfate Calcium Nitrate Potassium Nitrate Potassium Chloride Potassium Sulfate Urea	NH₄NO₃ (NH₄)₂SO₄ Ca(NO₃)₂ KNO₃ KCl K₂SO₄ CO(NH₂)₂	80.8 132.0 164.0 101.1 74.6 174.2 60.0
Element	Symbol	Atomic Weight
Calcium Carbon Chlorine Hydrogen Nitrogen Oxygen Phosphorus Potassium	Ca C Cl H N O P k	40.1 12.0 35.5 1.0 14.0 16.0 31.0 39.1

Using Chemicals

mg of fertilizer source/liter of water = (ppm)(formula weight)
(atomic weight of element)(number of units in formula of fertilizer source)

ppm = (mg of fertilizer/liter of water)(atomic weight of element)(number of units of element in formula of fertilizer source)
(formula weight of fertilizer source)

3) to convert mg/l to lbs/100 gal, multiply mg by 0.0008344

4) to convert lbs/100 gal to mg/l, divide lbs by 0.0008344

EXAMPLE: How many pounds of potassium sulfate (K₂SO₄) need to be dissolved in 100 gallons of water to make 100 ppm K solution. Get the formula weight of potassium sulfate (K₂SO₄) and the atomic weight of potassium from Table 14. Then:
1) mg of K₂SO₄ / liter of water = (100 x 174.2) Ã· (39.1 x 2) = 222.8 mg/L
2) 222.8 mg/L x 0.00083440 = 0.186 lbs potassium sulfate/100 gal

Using Premixed Fertilizers

mg of mixed fertilizer/liter of water = (ppm of N desired)(100)
(% N in fertilizer)

ppm of P = (mg of mixed fertilizer/liter of water)(% P₂O₅)(0.4366)
100

ppm of K = (mg of mixed fertilizer/liter of water) (% K₂O) (0.8301)
100

mg of mixed fertilizer/liter of water = (ppm of P desired)(100)
(% P₂O₅)(0.4366)

mg of mixed fertilizer/liter of water = (ppm of k desired)(100)
(% K₂O) (0.8301)

mg of mixed fertilizer/liter of water = (mg of mixed fertilizer/liter of water)(% N)
10

Table 18. Miscellaneous conversions used in fertilizer calculations
1 millimeter or cubic centimeter of water weighs 1 gram
1 liter of water weighs 1 kilogram
1 gallon of water weighs 8.34 pounds
1 part per million (ppm) 1 part per million 1 part per million	= 0.0001 percent = 1 milligram/liter =0.013 ounces in 100 gallons of water
1 percent 1 percent 1 percent 1 percent 1 percent	= 10,000 ppm = 10 grams per liter = 10,000 grams per kilogram = 1.33 ounces by weight per gallon of water = 8.34 pounds per 100 gallons of water
0.1 percent 0.01 percent 0.001 percent 0.0001 percent	= 1000 ppm = 100 ppm = 100 ppm = 100 ppm	= 1000 milligrams per liter = 100 milligrams per liter = 10 milligrams per liter = 1 milligram per liter
Approximate weight-volume measurements for making small volumes of water soluble fertilizers
1 cup	= 8 oz or 0.5 lbs of fertilizer
2 cups	= 1 lb of fertilizer
1 tablespoon	= 0.5 oz of fertilizer
2 tablespoons	= 1 oz of fertilizer
Useful conversions
1 ton/acre	= 20.8 grams/square foot
1 ton/acre	= 1 lb/21.78 square feet
1 gram/square foot	= 96 lbs/acre
1 lb/acre	= 0.0104 g/square foot
100 lbs/acre	= 0.2296 lbs/100 square feet
grams/square foot x 96	= lbs/acre
lbs/square foot x 43,560	= lbs/acre
100 square feet	= 1/435.6 or 0.002296 acres
Weight conversions from lbs/acre to weight/100 square feet
lbs/acre	amount applied/100 square feet
100	3.7 oz
200	7.4 oz
300	11.1 oz
400	14.8 oz
500	1 lb 2.5 oz
600	1 lb 6 oz
700	1 lb 10 oz
800	1 lb 13 oz
900	2 lb 1 oz
1000	2 lb 5 oz
2000	4 lb 10 oz
Percent to Ratio Conversion
2.0%	1:50
1.5%	1:67
1.0%	1:100
0.9%	1:111
0.8%	1:128
0.7%	1:143
0.6%	1:167
0.5%	1:200
0.4%	1:250
0.3%	1:333
0.2%	1:500

Table19. Osmocote® controlled-release fertilizers and their release periods¹
Analysis	Longevity²(months)	Product Name
14-14-14	3-4	Osmocote®³
19-6-12	3-4	Osmocote®³
13-13-13	8-9	Osmocote®³
18-6-12	8-9	Osmocote®³ Fast Start
18-6-12	8-9	Osmocote®³
17-7-12	12-14	Osmocote®³
15-9-12	3-4	Osmocote® Plus
15-9-12	5-6	Osmocote® Plus
15-9-12	8-9	Osmocote® Plus
15-9-12	12-14	Osmocote® Plus
15-9-12	14-16	Osmocote® Plus
16-8-12	8-9	Osmocote® Plus Minors Tablets
19-5-8 + Minors	8-9	Osmocote® Pro with Poly-S
19-5-9 + Minors	12-14	Osmocote® Pro with Poly-S
20-5-8 + Minors	8-9	Osmocote® Pro with Poly-S
24-4-8	8-9	Osmocote® Pro with Resin Coated Urea
24-4-7	12-14	Osmocote® Pro with Resin Coated Urea
24-4-6	14-16	Osmocote® Pro with Resin Coated Urea
21-4-7 w/ Mg & Fe	8-9	Osmocote® Pro with Resin Coated Urea
21-3-7 w/ Mg & Fe	12-14	Osmocote® Pro with Resin Coated Urea
22-4-9 + Minors	5-6	Osmocote® Pro with Resin Coated Urea
22-4-8 + Minors	8-9	Osmocote® Pro with Resin Coated Urea
22-4-7 + Minors	12-14	Osmocote® Pro with Resin Coated Urea
22-4-6 + Minors	14-16	Osmocote® Pro with Resin Coated Urea
20-4-9	8-9	Osmocote® Pro with Methylene Urea and Ureaform
20-4-8	12-14	Osmocote® Pro with Methylene Urea and Ureaform
23-4-8 + Minors	14-16	Osmocote® Pro + ScottKote™
19-7-10 + Fe	3-4	Osmocote® Pro with Uncoated NPK and Iron
18-7-10 + Fe	8-9	Osmocote® Pro with Uncoated NPK and Iron
17-7-10 + Fe	12-14	Osmocote® Pro with Uncoated NPK and Iron
13-10-13	5-6	Osmocote® Pro with IBDU and Minors
15-10-10	8-9	Osmocote® Pro with IBDU and Minors
18-8-8	8-9	Osmocote® Pro with IBDU and Minors
20-4-8	8-9	Osmocote® Pro with IBDU and Minors
18-5-9	12-14	Osmocote® Pro with IBDU and Minors
17-6-12 + Minors	3-4	Sierra® Tablets
17-6-10 + Minors	8-9	Sierra® Tablets
¹ From the Scotts Company and Subsidiaries, Marysville, OH 43041. ² At an average root substrate temperature of 70 degrees F (21 degrees C). ³ Six trace elements plus magnesium.

Table 20. Rates in lb/yd³ (kg/m³) for incorporation of three of the most popular formulations of Nutricote into greenhouse root substrates¹
Release Type (days³)	Sensitive Crops		Medium-Feeding Crops		Heavy-Feeding Crops
Release Type (days³)	*13-13-13*
70	2.5	(1.5)	5	(3.0)	8.5	(5.1)
100	3.5	(2.1)
140	5	(3.0)	9	(5.4)	13	(7.8)
180	6	(3.6)	11	(6.6)	17	(10.2)
270	8	(4.8)	13	(7.8)	21	(12.6)
360	11	(6.6)	15	(9.0)	25	(15.0)
	*14-14-14*
40	2	(1.2)	5	(3.0)	8	(4.7)
70	4	(2.4)	9	(5.4)	14	(8.3)
100	5	(3.0)	12	(7.1)	20	(11.9)
140	8	(4.7)	15	(9.0)	22	(13.0)
180	12	(7.1)	20	(11.9)	28	(16.6)
270	16	(9.5)	24	(14.2)	32	(19.0)
360	20	(11.9)	28	(16.6)	36	(21.3)
	*18-6-8*
70	2	(1.2)	4.5	(2.7)	7.5	(4.5)
100	3	(1.8)	6.5	(3.9)	11	(6.6)
140	4.5	(2.7)	8	(4.8)	12	(7.2)
180	6	(3.6)	11	(6.6)	14	(8.4)
270	8	(4.8)	13	(7.8)	16	(12.0)
360	11	(6.6)	15	(9.0)	18	(13.8)
¹ From Nelson, P.V. 1998. Greenhouse Operations and Management, 5th Âed. Published by Prentice Hall, Inc. Reprinted with permission.

Tables 21 through 22 are designed to assist growers in correcting the pH of the growing substrate.

Table 21. Materials and rates necessary to lower the pH level of greenhouse potting substrate 0.5 to 1.0 units¹
Material	Pounds to incorporate in lbs/yd³	Pounds to dissolve in 100 gal water²	Rate of change in pH
Aluminum sulfate	1.5	6.0	Rapid
Iron sulfate	1.5	6.0	Moderate
Finely ground elemental sulfur	0.75	-	Slow
¹ Adapted from Bailey, D.A. 1996. ² Apply this drench as a normal watering, about 1 quart per square foot or 8 fluid ounces per 6-inch pot.

Table 22. Approximate amount of materials required to change pH of peat-based potting mixes¹
Beginning pH	Pounds per cubic yard to change acidity to pH 5.7 for:
Beginning pH	50% Peat 50% Moss	100% Peat
7.5²	2.0	3.4
7.0	1.5	2.5
6.5	1.0	2.0
5.0³	2.5	3.5
4.5	5.6	7.4
4.0	7.9	11.5*
3.5	10.5*	15.58
¹ Adapted from Conover, C.A., and R.T. Poole. 1984. ² Add sulfur or acidifying mixture to lower pH to 5.7. *³ Add dolomitic lime or equivalent amount of calcium to raise pH to 5.7.* * Addition of more than 10 pounds of dolomitic per yd³ can cause micro-nutrient deficiencies.

Table 23 will help when applying various plant growth regulators.

Table 23A. Dilution/conversion chart for A-REST (0.0264% active ingredient)¹
Spray
Spray Solution (ppm)	Fluid Ounces per Gallon of Final Solution		Milliliters per Gallon of Final Solution	Milliliters per Liter of Final Solution
1	48		14.34	3.79
3	1.45		43.02	11.36
10	4.85		143.39	37.88
25	12.12		358.47	94.70
50	24.24		716.93	189.39
75	36.36		1075.40	284.09
100	48.48		1433.87	378.79
Drench
Dose (Milligrams per 6-in Pot)	Drench Volume per 6-in Pot* (Fluid Ounces)	ppm solution	Fluid Ounces per Gallon of Final Solution	Milliliters per Gallon of Final Solution	Milliliters per Liter of Final Solution
0.125	4	1.06	0.51	15.15	4.0
0.25	4	2.11	1.02	30.30	8.01
0.50	4	4.23	2.05	60.61	16.01
0.75	4	6.34	3.07	90.91	24.02
1.00	4	8.45	4.10	121.21	32.02
¹Adapted from Hammer, P.A. 1992. *2 fl oz/4-in pot; 3 fl oz/5-in pot; 10 fl oz/8-in pot

Table 23B. Dilution/conversion chart for CYCOCEL (11.8% active ingredient)¹
Spray
Spray Solution (ppm)	Fluid Ounces per Gallon of Final Solution		Milliliters per Gallon of Final Solution	Milliliters per Liter of Final Solution
1,000	1.08		32.08	8.47
1,500^A	1.63		48.12	12.71
2,000	2.17		64.16	16.95
2,500	2.71		80.20	21.19
3,000^B	3.25		96.24	25.42
5,000	5.42		160.40	42.37
Drench
Dose (Milligrams per 6-in Pot)	Drench Volume per 6-in Pot* (Fluid Ounces)	ppm solution	Fluid Ounces per Gallon of Final Solution	Milliliters per Gallon of Final Solution	Milliliters per Liter of Final Solution
355	6	2,000	2.17	64.18	16.95
532	6	3,000^B	3.25	96.18	25.42
710	6	4,000	4.34	128.36	33.90
¹Adapted from Hammer, P.A. 1992. ^ACommonly referred to as 1:80. ^BCommonly referred to as 1:40. *2 fl oz/2.25- to 3-in pot; 3 fl oz/4-in pot; 4 fl oz/5-in pot; 8 fl oz/8-in pot.

Table 23C. Dilution/conversion chart for B-NINE WSG (85% active ingredient)¹
Spray
Spray Solution (ppm)	Ounces per Gallon of Final Solution	Grams per Gallon of Final Solution	Grams per Liter of Final Solution
1,000	0.16	4.45	1.18
2,500	0.39	11.13	2.94
5,000	0.79	22.26	5.88
7,500	1.18	33.40	8.82
¹Adapted from Hammer, P.A. 1992.

Table 23D. Dilution/conversion chart for BONZI (0.4% active ingredient)¹
Spray
Spray Solution (ppm)	Fluid Ounces per Gallon of Final Solution		Milliliters per Gallon of Final Solution	Milliliters per Liter of Final Solution
1	0.032		0.95	0.25
3	0.096		2.84	0.75
5	0.160		4.73	1.25
10	0.320		9.46	2.50
15	0.480		14.20	3.75
25	0.800		23.66	6.25
45	1.440		42.59	11.25
60	1.920		56.78	15.00
90	2.880		85.17	22.50
Drench
Dose (Milligrams per 6-in Pot)	Drench Volume per 6-in Pot* (Fluid Ounces)	ppm	Fluid Ounces per Gallon of Final Solution	Milliliters per Gallon of Final Solution	Milliliters per Liter of Final Solution
0.1	4	0.85	0.03	0.8	0.21
0.2	4	1.69	0.05	1.6	0.42
0.5	4	4.23	0.14	4.0	1.06
1.0	4	8.45	0.27	8.0	2.11
1.9	4	16.06	0.51	15.2	4.02
¹Adapted from Hammer, P.A. 1992. * 2 fl oz/4-in pot; 3 fl oz/5-in pot; 10 fl oz/8-in pot.

Table 23E. Dilution/conversion chart for SUMAGIC (0.055% active ingredient)¹
Spray
Spray Solution (ppm)	Fluid Ounces per Gallon of Final Solution		Milliliters per Gallon of Final Solution	Milliliters per Liter of Final Solution
1	0.26		7.57	2
3	0.77		22.71	6
5	1.28		37.85	10
10	2.56		75.71	20
15	3.84		113.56	30
25	6.40		189.27	50
30	7.68		227.12	60
50	12.80		378.54	100
Drench
Dose (Milligrams per 6-in Pot)	Drench Volume per 6-in Pot* (Fluid Ounces)	ppm	Fluid Ounces per Gallon of Final Solution	Milliliters per Gallon of Final Solution	Milliliters per Liter of Final Solution
0.02	4	0.17	0.04	1.28	0.34
0.03	4	0.25	0.06	1.92	0.51
0.04	4	0.34	0.09	2.56	0.68
0.05	4	0.42	0.11	3.20	0.85
0.06	4	0.51	0.13	3.84	1.01
0.09	4	0.76	0.19	5.76	1.52
0.12	4	1.01	0.26	7.68	2.03
0.20	4	1.69	0.43	12.80	3.38
¹Adapted from Hammer, P.A. 1992. * 2 fl oz/4-in pot; 3 fl oz/5-in pot; 10 fl oz/8-in pot.

Table 23F. Dilution/conversion chart for FLOREL (3.9% active ingredient)¹
Spray
Spray Solution (ppm)	Fluid Ounces per Gallon of Final Solution	Milliliters per Gallon of Final Solution	Milliliters per Liter of Final Solution
300	0.97	28.72	7.59
325	1.05	331.11	8.22
500	1.62	47.86	12.64
750	2.43	28.89	18.97
975	3.16	93.34	24.66
1,000	3.24	95.73	25.29
¹Adapted from Hammer, P.A. 1992.

Table 23G. Dilution/conversion chart for PRO-GIBB (4% active ingredient)¹
Spray
Spray Solution (ppm)	Fluid Ounces per Gallon of Final Solution	Milliliters per Gallon of Final Solution	Milliliters per Liter of Final Solution
2.5	0.008	0.24	0.06
5.0	0.016	0.47	0.13
100.0	0.320	9.46	2.50
250.0	0.800	23.66	6.25
300.0	0.960	28.39	7.50
500.0	1.600	47.31	12.50
¹Adapted from Hammer, P.A. 1992.

Table 23H. Dilution/conversion chart for FASCINATION¹
Spray
ppm BA/GA	Fluid Ounces per Gallon of Final Solution	Milliliters per Gallon of Final Solution	Milliliters per Liter of Final Solution
1/1	0.007	0.2	0.06
5/5	0.04	1.1	0.3
10/10	0.07	2.1	0.6
25/25	0.18	5.3	1.4
50/50	0.36	10.5	2.8
75/75	0.53	15.8	4.2
100/100	0.71	21.0	5.5
¹Adapted from Hammer, P.A. 1992.

Tables 24 through 25 are designed to assist growers who desire to prepare their own substrate mix.

Table 24. Pre-plant fertilizer sources and rates of application^1,2
Nutrient Source		Rate per Cubic Yard (per m³)
Nutrient Source		Soil-Based Media	Soilless Media
*To provide calcium and magnesium*
When a pH rise is desired:	Dolomitic limestone	0-10 lb (0-6 kg)	10 lb (6 kg)
When no pH shift is desired:	Gypsum for calcium	0-5 lb (0-3 kg)	0-5 lb (0-3 kg)
When no pH shift is desired:	Epsom salt for magnesium	0-1 lb (0-0.6 kg)	0-1 lb (0-0.6 kg)
To provide phosphorus*
Superphosphate (0-45-0)		1.5 lb (0.9 kg)	2.25 lbs (1.3 kg)
*To provide sulfur*
Gypsum (calcium sulfate)		1.5 lbs (0.9 kg)	1.5 lbs (0.9 kg)
*To provide micronutrients: iron, manganese, zinc, copper, boron, molybdenum*
Esmigran		3-6 lbs (1.8-3.6 kg)	3-6 lbs (1.8-3.6 kg)
Micromax		1-1.5 lbs (0.6-0.9 kg)	1-1.5 lb (0.6-0.9 kg)
Promax		1-1.5 lbs (0.6-0.9 kg)	1-1.5 lb (0.6-0.9 kg)
F-555HF		3 oz (112 g)	3 oz (112 g)
F-111HR		1 lb (0.6 kg)	1 lb (0.6 kg)
*To provide nitrogen and potassium (optional)*
Calcium nitrate, or		1 lb (0.6 kg)	1 lb (0.6 kg)
Potassium nitrate		1 lb (0.6 kg)	1 lb (0.6 kg)
¹From Nelson, P.V. 1998. Greenhouse Operations and Management, 5th ed. Published by Prentice Hall, Inc. Reprinted with permission. ²Rates in this table are for crops other than seedlings. Only limestone is necessary in seedling substrates. Optional nutrient sources for seedling substrate include up to 1 lb (0.6 kg) each of superphosphate, gypsum, and calcium nitrate; no potassium nitrate; and the low end of the rate range for micronutrients. *These are maximum rates designed to supply phosphorus for three to four months if pH is maintained in a desirable range for the crop and the leaching percentage is at or below 20 percent.

Table 25. Cornell Peat-Lite Mix A for seedlings, bedding plants and potted plants*
Materials Used	Amount per Cubic Yard¹	Amount per Bushel
Spagnum peat moss	0.5 cubic yard (13 bushels)	0.5 bushel
Horticultural grade vermiculite #2 size for seed germination #2 or 3 for transplanting	0.5 cubic yard (13 bushels)	0.5 bushel
Superphosphate, or	1 to 2 pounds	20.5 to 41.0 grams (1 to 2 tablespoons)
Treble superphosphate²	0.5 to 1 pound	10.3 to 20.5 grams (0.6 to 1.2 tablespoons)
Ground dolomitic limestone²	5 to 10 pounds	103 to 206 grams (5.2 to 10.4 tablespoons)
Gypsum²	2.0 pounds	41 grams (2.5 tablespoons)
Calcium nitrate	0.5 pound	10 grams (1.2 tablespoons)
Potassium nitrate	0.5 pound	10 grams (1.2 tablespoons)
*Trace element material (Use Only One)*
Esmigran, or	4.0 pounds	81 grams (4.0 tablespoons)
Micromax	1.5 pounds	31 grams (1.7 tablespoons)
*Wetting agent (Use Only One³)*
Aqua-Gro 2000 granular, or	1.0 pound	---
Aqua-Gro 2000-L liquid⁴	3-5 fluid ounces	0.5 level teaspoon
PsiMatric liquid⁵	2-4 fluid ounces	0.5 level teaspoon
¹A cubic yard equals 27 cubic feet or approximately 22 bushels. A 15 to 20 percent shrink occurs in mixing. Therefore, an additional 5 cubic feet or 4 bushels are used to obtain a full cubic yard. ²If treble superphosphate is used, gypsum is added to supply sulphur. If only 5 pounds of limestone are used for pH control, then add the gypsum that supplied calcium and sulphur. ³The granular Aqua-Grow is preferred. ⁴3 ounces/yard for germination/seedlings, 5 ounces/yard for bedding plants and pot plants. ⁵2 ounces/yard for germination/seedlings, 4 ounces/yard for bedding plants and pot plants. *Adapted from Fonteno. W.C. 1994

Table 28. Coverage estimates for perlite, peat, topsoil and straw
Thickness	4 cu ft Perlite	6 cu ft Canadian peat (compressed)	*1 cu yd Peat mulches, Topsoil, etc.**	1 Bale
Thickness	4 cu ft Perlite	6 cu ft Canadian peat (compressed)	*1 cu yd Peat mulches, Topsoil, etc.**	Pinestraw	Wheatstraw
2 in	28 sq ft	72 sq ft	162 sq ft	90 sq ft	180 sq ft
1 in	48 sq ft	144 sq ft	324 sq ft	180 sq ft	360 sq ft
1/2 in	96 sq ft	288 sq ft	648 sq ft	360 sq ft	720 sq ft
1/4 in	192 sq ft	576 sq ft	1296 sq ft	720 sq ft	1440 sq ft
*1 cubic yard (yd³) = 27 cubic feet (ft³)

Tables 29 through 30 help determine correct spacing and number of plants at each spacing for both greenhouse and field situations.

Table 29. Plant spacing guide (greenhouse)
Spacing	Plants/sq ft	Plants/A of production area	Plants/A of ground covered*
8" x 9"	2.0	87,000	58,000
8" x 8"	2.3	98,000	65,000
8" x 7"	2.6	114,000	76,000
8" x 6"	3.0	130,000	87,000
6" x 7"	3.4	147,000	98,000
6" x 6"	4.0	174,000	116,000
6" x 5"	4.8	208,000	139,000
5" x 5"	5.8	252,000	168,000
5" x 4"	7.2	313,000	209,000
5" x 3"	9.6	418,000	279,000
4" x 3"	12.0	522,000	348,000
*Assuming 1/3 of production area devoted to aisles, etc.

Table 30. Plant spacing guide (field/orchard)*
Spacing Between Rows of Plants	Spacing Between Plants Within the Row
	Feet	6	8	10	12	14	16	18	20	22	24	26
	4	1815	1361	1089	907	777	680	605	544	495	453	418
	6	1218	907	726	605	518	453	403	363	330	302	279
	8	907	680	544	453	388	339	302	272	247	226	209
	10	726	544	435	362	311	272	242	218	207	181	167
	12	605	453	362	302	259	226	201	181	165	151	139
	14	518	388	311	259	222	194	172	155	141	129	119
	16	453	339	272	226	194	169	151	136	123	113	104
	18	403	302	242	201	172	151	134	121	110	100	93
	20	363	272	218	181	155	136	121	108	99	90	83
	22	330	247	207	165	141	123	110	99	90	82	76
	24	302	226	181	151	129	113	100	90	82	75	69
	26	279	209	167	139	119	104	93	83	76	69	64
	Number of Plants Per Acre
*To determine the number of plants per acre for spacings not given in the table, multiply the distance in the row by the distance between rows and divide that number into 43,560.

Formulas for calculating greenhouse volume

These formulas are helpful in determining heating and cooling costs for greenhouses.

For the following formulas:

L = length
W = width
W₁ = width of short span
W₂ = width of long span
H_e = height from floor to eave
H_r = height from eave to top

Uneven-span greenhouses

Figure 1-A. Formula for calculating uneven-span greenhouse volume.

Greenhouse volume in cubic feet = [(W x H_e) + ([W₁ x H_r] ÷ 2) + ([W₂ x H_r] ÷ 2)] x L

Even-span greenhouses

Figure 1-B. Formula for calculating even-span greenhouse volume.

Greenhouse volume in cubic feet = [(W x H_e) + ([W x H_r] ÷ 2)] x L

Quonset structures

Figure 1-C. Formula for calculating quonset greenhouse volume.

Greenhouse volume in cubic feet = [(W x H_e) + ([3.14 x H_r²] ÷ 2)] x L

Acknowledgments

The authors wish to acknowledge the following sources, from which certain tables were adapted for use in this publication.

Bailey, D. A. (1996). Alkalinity, pH and Acidification. In D. Reed (Ed.), A Grower's Guide to Water, Media, and Nutrition for Greenhouse Crops. Ball Publishing.

Bailey, D. A., & Powell, M. A. (1999). Installation and maintenance of landscape bedding plants (Horticulture Information Leaflet 555). N.C. State University and N.C. A&T State University Cooperative Extension. https://digital.ncdcr.gov/Documents/Detail/installation-and-maintenance-of-landscape-bedding-plants/3692207

Ball, V. (Ed.). Ball RedBook: Greenhouse growing (16th ed.). (1997). Ball Publishing.

Cavins, T. J., Gibson, J. L., Whipker, B. E., & Fonteno, W. C. (2000, December). pH and EC meters — Tools for substrate analysis (Research Report Florex.001). North Carolina State University. https://fertdirtsquirt.com/pdf/PHECmeters.pdf

Conover, C. A., & Poole, R. T. (1984). Light and fertilizer recommendations for production of acclimatized potted foliage plants. Foliage Digest, 7(8), 1–6.

Cornell University. (1977). Cornell recommendations for commercial floricultural crops: Part 1, cultural practices and production programs. https://digital.library.cornell.edu/catalog/chla7134041_8300_001

Holcomb, E. J. (Ed.). (1994). Bedding plants IV: A manual on the culture of bedding plants as a greenhouse crop (4th ed.). Ball Publishing.

Hummert International. (1999). Hummert's helpful hints, 1999–2000 ed.

Nelson, P. V. (1998). Greenhouse operation and management (5th ed.). Prentice Hall.

Ohio Florist Association Services, Inc. (1999). Tips on growing bedding plants, 4th ed.

Ohio Florist Association Services, Inc. (1992). Tips on the use of chemical growth regulators on floriculture crops.

University of California Cooperative Extension Service. (n.d.). Tons to teaspoons (Pubication No. L2285).

Whipker, B. E., Bailey, D. A., Nelson, P. V., Fonteno, W. C., & Hammer, P. A. (n.d.). Greenhouse media lab acid addition calculator to control alkalinity in irrigation water. Cooperative Extension Services of the Northeast States.

DISCLAIMER: Trade named products listed does not imply endorsem*nt over similar products, which may also be available.

Status and Revision History
Published on Mar 01, 2002
Unpublished/Removed on Feb 24, 2009
Published on Apr 29, 2009
Published with Full Review on Apr 25, 2012
Published with Full Review on Feb 22, 2016
Published with Full Review on Aug 01, 2017
Published with Full Review on Aug 10, 2020

mg of fertilizer source/liter of water =	(ppm)(formula weight)
	(atomic weight of element)(number of units in formula of fertilizer source)

ppm =	(mg of fertilizer/liter of water)(atomic weight of element)(number of units of element in formula of fertilizer source)
	(formula weight of fertilizer source)

mg of mixed fertilizer/liter of water =	(ppm of N desired)(100)
	(% N in fertilizer)

ppm of P =	(mg of mixed fertilizer/liter of water)(% P₂O₅)(0.4366)
	100

ppm of K =	(mg of mixed fertilizer/liter of water) (% K₂O) (0.8301)
	100

mg of mixed fertilizer/liter of water =	(ppm of P desired)(100)
	(% P₂O₅)(0.4366)

mg of mixed fertilizer/liter of water =	(ppm of k desired)(100)
	(% K₂O) (0.8301)