Fertilizer for Vegetable Gardens



Fertilizers for Vegetable Gardens

Paul Schnare

Saturday, April 12, 2003


There are many different fertilizers on the market today.  How do you know which one to use on your vegetable garden?  If you keep in mind a simple rule of thumb, you can easily decide which fertilizer to use at the appropriate time.  Nitrogen encourages shoot and leaf development, phosphorous encourages root development, and potassium encourages fruit development.

On each bag of fertilizer there are three bold numbers listed.  These numbers refer to the percent of nitrogen, phosphorous, and potassium in the bag.  You also may find numbers that refer to other plant nutrients such micronutrients, and secondary macronutrients. 

When you first transplant vegetable plants you want to encourage root development, because a good strong plant has a good strong root system.  Therefore immediately after transplanting, and within a week or two after transplanting, you want to fertilize with a high phosphorous fertilizer such as a 9-59-8. 

After this initial fertilization, you then want to switch to a more balanced fertilizer, yet still having the middle number phosphorous higher than the first number nitrogen.  Use something like 11-15-11 with micronutrients.  By keeping the middle number higher than the first number, you will encourage your vegetables to produce roots and fruits at the expense of leaves and shoots.

Micronutrients are also often required for good fruit development.  Usually the soils in the Heartland have sufficient micronutrients in them.  Yet occasionally you will find a situation when there is a deficiency.  Therefore by using a fertilizer with micros in it, you can eliminate this potential problem.

Gardeners often tell me that they have great looking tomato plants, growing up to six and eight feet, that produce no tomatoes.  Upon questioning, I usually find that they have fertilized with 12-12-12 or ammonium nitrate.  By using a high nitrogen fertilizer, or by using a balanced fertilizer, they have encouraged their tomato plants to produce leaves and shoots at the expense of fruit development. 

When these gardeners switch to using a 9-59-8 upon transplanting, and then side dress during the season with 11-15-11 then find that they have a great tomato crop again.  Use of the proper fertilizer at the proper time is essential for good vegetable production.