Greenhouse Tomatoes (Code #180)
Soil Test RatingPotassium

Low K

Coast: 0-70 lbs/A

Pied: 0-120 lbs/A

Medium K

Coast: 71-170 lbs/A

Pied: 121-250 lbs/A

High K

Coast: 171-275 lbs/A

Pied: 251-400 lbs/A

Very High K

Coast: 275+ lbs/A

Pied: 400+ lbs/A

PhosphorusRecommended Pounds N-P205-K20 per Acre

Low P

Coast: 0-30 lbs/A

Pied: 0-20 lbs/A

*-200-200*-200-150*-200-100*-200-75

Medium P

Coast: 31-60 lbs/A

Pied: 21-40 lbs/A

*-150-200*-150-150*-150-100*-150-75

High P

Coast: 61-100 lbs/A

Pied: 41-75 lbs/A

*-100-200*-100-150*-100-100*-100-75

Very High P

Coast: 100+ lbs/A

Pied: 75+ lbs/A

*-70-200*-70-150*-70-100*-70-75

Coast = Coastal Plain    Pied = Piedmont, Mountain, and Limestone Valley

Recommendations:

Recommended pH:6.3 to 6.8. If the pH is less than 6.3, see Lime Table B.
Magnesium:

If soil test Mg level is low and lime is recommended, use dolomitic limestone; if soil test Mg is low and lime is not recommended, apply 25 pounds of Mg/Acre.

Coastal PlainLow: 0 - 60 lbs/acre Medium: 61 - 120 lbs/acre High: >120 lbs/acre
Piedmont Low: 0 - 120 lbs/acre Medium: 121 - 240 lbs/acre High: >240 lbs/acre
Zinc:If the Zn soil test level is low, apply 5 pounds of zinc per acre.
Calcium:If soil test calcium is less than 800 pounds/acre and pH is 6.5 or greater, apply 1,000 pounds gypsum per acre.

Fact Sheet:

*Common problems are overfertilization with nitrogen (N) and inadequate levels of calcium (Ca) and magnesium (Mg). For best results, be sure the soil pH is 6.0 or greater. Do not apply substantial quantities of nitrogen fertilizer before planting, since most of the nitrogen needs can be supplied by means of the irrigation water during the growing season. The initial nitrogen application should not exceed 60 pounds nitrogen per acre. However, if the soil is high in fertility, do not apply more than 30 pounds nitrogen per acre. Slow release nitrogen fertilizers have not been effective nitrogen suppliers and are not recommended. No additional nitrogen fertilizer should be applied until the first fruit set. Applications of nitrogen should be determined based on plant analysis results and interpretations.

Monitor the nutrient status of the plant with plant analysis to determine the nutrient balance and additional fertilizer needs. This is particularly important when plants are grown in an artificial soil mix.

When artificial mixes are used, be sure to add the additional calcium in the form of larger quantities of limestone and gypsum. It is generally advisable to leave the osmocote out of the mix. The needed nitrogen can be supplied through the irrigation water. For a 50-50 peat-vermiculite mix, per cubic yard of mix apply:

  • 12.0 pounds dolomitic limestone
  • 2.5 pounds 0-20-0 (superphosphate)
  • 1.5 pounds calcium nitrate
  • 5.0 pounds calcium sulfate (gypsum)
  • 5.0 pounds 7-40-0 MagAmp
  • 1.0 ounces iron (chelated such as NaFe 138 or 330)
  • 6.0 ounces Frited Trace Element 503*

*If not available, apply 0.5 ounces sodium borate (borax) per cubic yard.