Application rates & directions
Find what you are feeding, then weigh the amount; a kitchen scale works. Soil amounts depend on the phosphorus level on your soil test, leaf sprays follow the manufacturer’s directions for this product, and nutrient solutions follow your recipe. The calculator does the math for any number of plants, trees, or gallons.
Tomatoes, peppers, and other vegetables
Find your soil test’s phosphorus level in the first column and read across. Apply it once, before planting: spread each plant’s amount over its 3 × 3 ft space, or the bed amount over the bed, and work it into the top 4 to 6 inches.
Monopotassium Phosphate 0-52-34 per vegetable plant and per 100 sq ft of vegetable or flower bed, by soil-test phosphorus. Rates of 0.40, 0.30, 0.20, and 0.10 lb of phosphate (P₂O₅) per 100 sq ft from Iowa State Extension and the University of Minnesota (BU-01731, Table 23); level names from Minnesota’s Table 6
| Soil-test phosphorus | Each tomato or vegetable plant (3 × 3 ft of space) | Each 100 sq ft of bed |
|---|
| Low: Bray-P1 0–5 ppm, Olsen-P 0–3 ppm | 31 g | 349 g (0.77 lb) |
|---|
| Medium: Bray-P1 6–10, Olsen-P 4–7 | 24 g | 262 g (0.58 lb) |
|---|
| High: Bray-P1 11–15, Olsen-P 8–11 | 16 g | 174 g (0.38 lb) |
|---|
| High: Bray-P1 16–25, Olsen-P 12–18 | 7.9 g | 87 g (0.19 lb) |
|---|
| Very high: Bray-P1 over 25, Olsen-P over 18 | None | None |
|---|
The per-plant amount assumes about 3 × 3 feet for each plant; Iowa State spaces caged tomatoes 2½ to 3 feet apart and sprawling plants 3 to 4 feet apart. For other spacing, use the calculator. Every gram also adds 0.34 g of potash (K₂O). Your lab report names the test: Minnesota uses Bray-P1 on soils at pH 7.4 or below and Olsen-P above. These tables come from the Upper Midwest and are not split by crop; critical levels differ by crop and season, and the California lettuce guideline suggests a small starter for winter and spring lettuce at Olsen-P levels up to about 55–60 ppm. If your lab or state Extension service gives a phosphate recommendation in pounds of P₂O₅, use the soil test report formula below.
No soil test? Get one before adding phosphorus to soil. The University of Minnesota says a soil test is needed for accurate fertilizer recommendations, and Washington State University Extension notes that non-agricultural soils generally have adequate phosphate. Minnesota warns that excess phosphorus on high-testing soils can degrade water quality.
Already planted? Phosphorus barely moves in soil, so these sources work it in before planting and give no amount to sprinkle around plants already growing. For plants already in the ground, the manufacturer’s 1% leaf spray (below) is the option on this page; apply the soil amount before your next planting.
Pears, apples, and other fruit trees, shrubs, and berries
Measure across the branches from tip to tip, find your soil test’s phosphorus level, and read across. Each tree amount covers the ground under the branches and 2 feet beyond the branch tips, the area the University of Minnesota fertilizes. For shrubs and berries, measure the bed, row, or hedge you will fertilize.
Monopotassium Phosphate 0-52-34 per fruit tree by branch spread, and per 100 sq ft of shrubs or berries, by soil-test phosphorus. Rates of 0.20, 0.10, and 0.05 lb of phosphate (P₂O₅) per 100 sq ft from the University of Minnesota (BU-01731, Tables 6 and 27); Iowa State Extension gives the same rates for trees and shrubs
| Soil-test phosphorus | Tree, branches 6 ft across | 10 ft across | 15 ft across | 20 ft across | Each 100 sq ft of shrubs or berries |
|---|
| Low: Bray-P1 0–5 ppm, Olsen-P 0–3 ppm | 137 g | 269 g | 1.09 lb (495 g) | 1.74 lb (789 g) | 174 g (0.38 lb) |
|---|
| Medium: Bray-P1 6–10, Olsen-P 4–7 | 69 g | 134 g | 247 g | 395 g | 87 g (0.19 lb) |
|---|
| High: Bray-P1 11–25, Olsen-P 8–18 | 34 g | 67 g | 124 g | 197 g | 44 g (0.10 lb) |
|---|
| Very high: Bray-P1 over 25, Olsen-P over 18 | None | None | None | None | None |
|---|
Minnesota applies phosphorus to established fruit trees, shrubs, and berries in spring or fall. Phosphorus barely moves in soil, so for an established tree Minnesota places it below the surface: make holes 12 to 18 inches deep and about 2 feet apart with a soil auger, from at least 3 feet out from the trunk to 2 feet beyond the branch tips, divide the amount equally among the holes, and mix it into the soil used to refill them. For a new tree, shrub, or berry planting, work it into the top 4 to 6 inches before planting; around established shrubs and berries, spread it evenly and work it lightly into the soil. Iowa State notes that healthy, vigorous trees and shrubs in home landscapes generally do not need fertilizer, so feed them only where a soil test shows a need.
Potash. This product adds potash with its phosphorus, so compare it with what your potassium test calls for. Where Iowa State recommends no potash (over 200 ppm potassium for gardens, over 150 ppm for trees and shrubs), a phosphorus source without potash, such as Monoammonium Phosphate 12-61-0, fits better. If you need more potash than it adds, use a potassium-only fertilizer such as Potassium Sulfate 0-0-53.
Potash (K₂O) recommended by soil-test potassium (Iowa State Extension), in lb per 100 sq ft, to compare with the potash this product adds
| Soil-test potassium (ppm) | Vegetable and flower gardens | Trees and shrubs |
|---|
| 0–50 | 0.40 | 0.20 |
|---|
| 51–100 | 0.30 | 0.10 |
|---|
| 101–150 | 0.20 | 0.05 |
|---|
| 151–200 | 0.10 | 0 |
|---|
| Over 200 | 0 | 0 |
|---|
Leaf sprays (the manufacturer’s directions)
The manufacturer’s directions for this 0-52-34 give the spray strengths below. A 1% spray is 1 kg per 100 liters: 10 g per liter, or 38 g per US gallon. Weigh the product, dissolve it in the full amount of water, and spray the leaves.
Leaf-spray strengths and timing from the manufacturer’s directions for this 0-52-34 product, with the weight of product per gallon and per liter of water
| Plants | Spray strength | Per US gallon of water | Per liter of water | When |
|---|
| Most vegetables and field crops, including tomato and pepper, young leaves | 1% | 38 g | 10 g | No schedule given |
|---|
| Vegetables and field crops, mature leaves or more tolerant crops | Up to 2% | Up to 76 g | Up to 20 g | No schedule given |
|---|
| Peach, plum, cherry, apricot, and other stone fruits | 1–2% | 38–76 g | 10–20 g | 2 to 4 sprays from fruit set to fruit coloring |
|---|
| Citrus | 1–3% | 38–114 g | 10–30 g | 2 or 3 sprays a month apart during early fruit development, starting 1 month after fruit set |
|---|
| Table grapes | 1–2% | 38–76 g | 10–20 g | 1 spray at fruit set and 1 during ripening |
|---|
| Wine grapes | 2% | 76 g | 20 g | 1 spray at fruit set and 1 during ripening |
|---|
| Olives | 3–5% | 114–189 g | 30–50 g | 1 in early spring, 2 during fruit development, and 1 during fruit sizing and oil filling |
|---|
| Bananas | 1–2% | 38–76 g | 10–20 g | 2 to 6 sprays |
|---|
- Start at the low end, and test first. The manufacturer advises spraying a small area before treating a whole crop, to see whether the spray causes any damage.
- Keep the tank simple. Do not mix it with calcium or magnesium fertilizers, such as calcium nitrate or Epsom salt, in the spray tank. Iron, manganese, zinc, and copper in the same tank must be chelated.
- Sprays supplement soil feeding; they do not replace it. The manufacturer describes leaf sprays as an optional supplement where plants need high phosphorus and potassium. University field trials found no yield benefit from monopotassium phosphate sprays on corn (Iowa State, one season in 1999, where 5 lb per acre reduced yield by about 3%) or potato (UF/IFAS, two 3% sprays).
- Pears and apples. The manufacturer gives no spray strength for them. Its programs for commercial pear and apple orchards in the Benelux countries and Germany spray 5 to 10 kg per hectare (4.5 to 8.9 lb per acre) 3 to 4 times from 6 weeks after flowering, with the final rate set by leaf analysis, and spray no fertilizer for 2 to 3 weeks after flowering, to avoid scorch. For a backyard tree, use the soil table above.
Florida citrus groves (UF/IFAS Extension). UF/IFAS recommends 8 lb of K₂O per acre per application for mature citrus trees, from sources that include potassium nitrate and monopotassium phosphate. In this product that is 23.5 lb per acre, which also supplies 12.2 lb of P₂O₅. UF/IFAS reports that post-bloom sprays in late April have been found to increase fruit size and yield, and reports no fruit burn when 15 lb of monopotassium phosphate per acre was applied in 32.5 gallons of water per acre, or in 10 gallons by airplane; those examples used less than the full rate, and it gives no spray volume for the full rate. At the manufacturer’s 1–3% citrus strength, 23.5 lb needs about 94 to 282 gallons of water per acre; set the volume with your grove advisor.
Hydroponic and fertigation nutrient solutions
Formula. Grams of product = phosphorus target (ppm P) × liters of final solution ÷ 226.9. Multiply US gallons by 3.785 for liters. If your recipe writes the target as P₂O₅, multiply it by 0.4364 first. Each ppm of phosphorus from this product also brings 1.24 ppm of potassium.
University phosphorus targets for nutrient solutions that use monopotassium phosphate, with the weight of this 0-52-34 product that supplies them in the final solution
| Target | Source | Per 100 US gal | Per 1,000 L | Potassium it adds |
|---|
| 31 ppm P | Cornell modified Sonneveld recipe for lettuce, leafy greens, and herbs (51.5 g of monopotassium phosphate per 100 gal); also the Penn State Extension recipe example | 51.7 g | 137 g | 38.6 ppm K |
|---|
| 39 ppm P | University of Arizona CEAC recipe for tomato, cucumber, and pepper, as published by Cornell (64.9 g per 100 gal) | 65.1 g | 172 g | 48.5 ppm K |
|---|
| 50 ppm P | UF/IFAS hydroponic tomato, every growth stage; its Formula 3 dissolves 5.5 lb in a 30-gallon stock tank injected at 1:100 | 83.4 g | 220 g | 62.2 ppm K |
|---|
Count the potassium and the nitrogen. This product supplies only part of each recipe’s potassium: Cornell’s lettuce recipe totals 210 ppm K, and UF/IFAS’s tomato targets run from 120 to 200 ppm K, with the rest coming from potassium nitrate, potassium sulfate, or potassium chloride. It supplies no nitrogen, so the recipes take theirs from calcium nitrate and potassium nitrate, with a little ammonium nitrate in some. If your water already carries phosphorus or potassium, subtract it from the target.
Keep it away from calcium concentrates, and test hard water. The manufacturer’s directions say not to mix it with calcium or magnesium fertilizers: use two tanks, or apply them at different times. Cornell notes that calcium can combine with phosphates and sulfates to form insoluble precipitates, so the Cornell, Penn State, and UF/IFAS recipes keep calcium nitrate in one stock tank and this product in the other. Magnesium sulfate never goes in the calcium tank. To follow the manufacturer’s directions exactly, dissolve it in a third tank or apply it at a different time; with two tanks, the university recipes put it with this product, so if you follow one, check that stock for cloudiness. Recipes name the tanks differently (Cornell’s phosphate tank is B, UF/IFAS’s is A), so go by the contents, not the letter. The two concentrates meet only in the diluted final solution, and at recipe strength that solution holds calcium, phosphate, and sulfate together: Cornell’s lettuce recipe carries 90 ppm calcium with 31 ppm phosphorus. Hard source water is a separate risk in drip and fertigation lines: UC Agriculture and Natural Resources reports that phosphorus fertilizers injected into irrigation water with more than about 40–50 ppm calcium or magnesium (2.5 meq/L) may form precipitates that are difficult to dissolve out of emitters. Before injecting, jar-test: mix the fertilizer into your water at the concentration that will occur in the line, let it stand overnight, and look for cloudiness or sediment.
It dissolves up to about 208 g per liter at 20 °C (Safety Data Sheet), far above what the recipes use: UF/IFAS’s Formula 3 stock holds about 22 g per liter. A 1% solution measures pH 4.2 to 4.9, so measure pH and EC after mixing. For soil crops on drip, inject phosphorus only where a soil test, tissue test, or advisor calls for it: for drip-irrigated processing tomatoes, UC Davis specialist Tim Hartz writes that in-season phosphorus fertigation is seldom necessary when adequate phosphorus was applied before or at planting.
California field and vegetable crops (California Crop Fertilization Guidelines)
Phosphate guidelines per acre from the CDFA–FREP and UC Davis California Crop Fertilization Guidelines (Olsen, or bicarbonate, soil test), with the weight of this 0-52-34 product that supplies them and the potash it adds
| Crop and soil test | Guideline (lb P₂O₅ per acre) | This product per acre | Potash it adds per acre |
|---|
| Processing tomato, Olsen-P below 10 ppm | 60–100 | 115–192 lb | 39–65 lb K₂O |
|---|
| Processing tomato, 10–20 ppm | 50–80 | 96–154 lb | 33–52 lb K₂O |
|---|
| Processing tomato, above 20 ppm | Unlikely to respond; a small starter may help root growth in cold soil | No rate given | None |
|---|
| Lettuce, below 10 ppm | Up to 200 may be needed, especially when soil is below 60 °F | Up to 385 lb | Up to 131 lb K₂O |
|---|
| Lettuce, 30–40 ppm | No more than 100 | No more than 192 lb | Up to 65 lb K₂O |
|---|
| Lettuce starter, winter or spring, 40 to 55–60 ppm | 20 | 38 lb | 13 lb K₂O |
|---|
These are California field guidelines, not home-garden rates, and the lettuce guideline gives no figure between 10 and 30 ppm. The tomato figures are the total for the year, including any starter; the guideline applies most preplant phosphorus in a band and places a starter band 1 to 2 inches below the seed. The lettuce guideline bands about 2 inches below and 2 inches to the side of the seed row and keeps high-analysis fertilizers a safe distance from the plants. The guidelines are written for phosphate; count the potash this product adds toward the crop’s potassium.
From a soil test report
Formula. Pounds of this product = pounds of P₂O₅ your report calls for ÷ 0.52. The potash it adds = pounds of product × 0.34. If the report gives pounds per acre, divide by 43.56 for pounds per 1,000 sq ft. For example, 60 lb of P₂O₅ per acre is 115 lb of this product per acre, adding 39 lb of K₂O. Apply it the way the report says, and count the potash toward the report’s potassium recommendation.
Your package label
This page gives university rates matched to your soil test or recipe and the manufacturer’s spray strengths, and does not restate the directions printed on your package. If the directions on your package differ from this page, email questions@greenwaybiotech.com before applying.
Uses with no amount on this page
This page gives no amount for lawns, transplant starter solutions, aquaponics, or watering containers or houseplants with this product alone, and no spray strength for pears, apples, or plants not in the spray table. For lawns and other crops, apply your soil report’s P₂O₅ recommendation with the formula above, or email questions@greenwaybiotech.com with your plants, growing method, and soil or water test.
Frequently asked questions
What is the difference between MKP 0-52-34 and MAP 12-61-0?
Both are water-soluble phosphates. MKP (monopotassium phosphate) supplies 52% available phosphate (P₂O₅) and 34% soluble potash (K₂O) with no nitrogen. MAP 12-61-0 (monoammonium phosphate) supplies 61% P₂O₅ and 12% nitrogen, all of it ammonium, with no potassium. Choose MKP when a recipe needs phosphorus without adding ammonium and the potassium fits; choose MAP 12-61-0 when the recipe can use some ammonium or the soil is already high in potassium.
How much do I use for my tomato plants?
Go by a soil test. For a tomato or other vegetable plant with about 3 × 3 feet of space, Iowa State and University of Minnesota Extension rates work out to 31 g of this product per plant where soil phosphorus tests low (Bray-P1 0–5 ppm or Olsen-P 0–3 ppm), 24 g where it tests medium (6–10 or 4–7 ppm), 16 g or 7.9 g where it tests high, and none where it tests very high (over 25 or over 18 ppm). Spread each plant’s amount over its space and work it into the top 4 to 6 inches, once, before planting. A whole bed takes 349 g down to 87 g per 100 sq ft. For plants already growing, the manufacturer’s directions give a leaf spray of 38 g per gallon of water (1%) on young leaves of most vegetables.
How much do I use for a pear or other fruit tree?
Measure across the branches from tip to tip and go by a soil test. Using University of Minnesota rates over the ground out to 2 feet beyond the branch tips, a tree with branches 10 feet across takes 269 g where soil phosphorus tests low (Bray-P1 0–5 ppm or Olsen-P 0–3 ppm), 134 g where it tests medium, 67 g where it tests high, and none where it tests very high. For an established tree, divide it among holes 12 to 18 inches deep and 2 feet apart, from 3 feet out from the trunk to 2 feet beyond the branch tips, in spring or fall. Iowa State Extension notes that healthy, vigorous trees in home landscapes generally do not need fertilizer.
Can I spray it on leaves?
Yes. The manufacturer’s directions give a 1% spray (38 g per gallon of water, or 10 g per liter) on young leaves of most vegetables and field crops, up to 2% on mature leaves or more tolerant crops, 1–2% for stone fruits and table grapes, 1–3% for citrus, and 3–5% for olives, with timing for each. Spray a small area first, and keep calcium and magnesium fertilizers out of the tank. Sprays supplement soil feeding: university field trials on corn and potato found no yield benefit from them. The manufacturer gives no spray strength for pears or apples.
How much do I add to a hydroponic reservoir?
Grams of product = your phosphorus target in ppm P × liters of final solution ÷ 226.9. For 31 ppm P, the level in Cornell’s modified Sonneveld recipe, that is 51.7 g per 100 US gallons; for UF/IFAS’s 50 ppm P for hydroponic tomatoes, 83.4 g per 100 gallons. Each ppm of phosphorus also adds 1.24 ppm of potassium, so count it in your recipe. Weigh the product on a scale.
Can I mix it with calcium nitrate or Epsom salt?
Calcium nitrate: never in the same concentrate or spray tank. Calcium combines with phosphates to form insoluble precipitates that settle out and can clog emitters, so keep calcium nitrate in its own stock tank; injected at the same time, the two meet in the water line, where they are diluted. Epsom salt: keep it out of the spray tank, as the manufacturer’s directions say. In hydroponic stock tanks, the Cornell, Penn State, and UF/IFAS recipes dissolve magnesium sulfate with this product, although the manufacturer keeps magnesium fertilizers separate; if you follow a recipe, check the stock for cloudiness.
Is it a bloom booster?
It is not sold as one. It supplies phosphorus and potassium with no nitrogen. Washington State University Extension horticulturist Linda Chalker-Scott found no scientific evidence that roses need high levels of phosphate for any reason, and notes that non-agricultural soils generally have adequate phosphate. Use it where a soil test or your nutrient recipe calls for phosphorus, at the rates on this page.
Will it lower the pH of my nutrient solution?
It is acidic: a 1% solution measures pH 4.2 to 4.9, according to the Safety Data Sheet. How far it moves your solution depends on the amount and on your water’s alkalinity, so measure pH and EC after mixing and adjust to your recipe’s target.
How much phosphorus and potassium does it add?
The label states phosphorus and potassium as oxides: 52% P₂O₅ and 34% K₂O. For solution math, that is 22.7% phosphorus (P₂O₅ × 0.4364) and 28.2% potassium (K₂O × 0.8302) by product weight, so 1 g per liter of solution adds 227 ppm P and 282 ppm K, and 1 g per US gallon adds 60 ppm P and 75 ppm K.
Can it control powdery mildew?
It is sold and registered as a fertilizer, not a pesticide, so we make no disease-control claim for it and give no rate for that use. For powdery mildew, use a product registered for it and follow its label.
Is it organic?
No. It is a manufactured mineral salt, and we do not sell it for certified organic production. If you farm under organic certification, your certifier decides which inputs you may use.
