Many folks use what I feel to be the wrong approach to fertilizing the home vegetable garden. In fact probably the majority of the American population assumes wrongly that twice or three times a year you put some fertilizer around your vegetable plants and that takes care of their nutritional needs for the season; and you do this again year after year. I think we behave this way because that is how commercial growers feed their vegetable fields.
My way of thinking about feeding the vegetable plants is combining the use of some slow release granular organic fertilizer with the effects of managing the soil with organic matter and some compost. Soil containing plenty of organic matter has a robust population of microbes and other soil creatures whose job is to break down that organic matter into its various chemical components. Those chemicals become food for the plants.
So when we think about feeding our garden, we think about adding organic matter, introduced as mulch, first and then think of fertilizer as being a supplement, at least until after four or five years of adding organic matter. At that time, we can probably stop using any general purpose fertilizer. The soil food web provides all of our vegetables with as much food as they need without the help of additional fertilizer.
Organic Matter As Food In The Vegetable Garden
One of the variables in any fertilizing program is measuring the amount of nitrogen available to the plants over time. Most vegetables will be happy with having 2 to 3 pounds of nitrogen per 1000 square feet over the growing season. [Note – turfgrass needs 4 lbs. of N per 1000 square feet] Generally 3 applications of quick-acting nitrogen fertilizer or one application of slow release nitrogen fertilizer provides 3 to 4 pounds of N per 1000 square feet.
However, those of us who pay attention to our soil and make sure there is an addition of organic matter to our soil every year, have something else going on down below the soil’s surface. Earthworms are coming to the surface and grabbing a piece of organic matter and pulling it down into the soil. The earthworms eat some of their harvest but also spread uneaten particles around for other creatures to chomp on. Soil with only 5 earthworms per cubic foot will get 1 lb. of N from those worms each year. Most gardens having had organic matter added yearly have 10 to 15 worms per cubic feet; that is 3 lbs of N per year from earthworm poop alone.
Nitrifying bacteria will produce about the same amount of N each year as do the earthworms. Other microbes contribute more for a total of 2 to 3 more pounds of N per 1000 square feet. Why are you using any fertilizer?
ADD ORGANIC MATTER IN THE FORM OF MULCH EACH YEAR AND REDUCE AMOUNT OF FERTILIZER NEEDED EACH YEAR.
Fertilizer Program For Vegetables
Granulated fertilizer comes in two forms – one is made of synthetic materials and is cheapest; the other is made of natural materials or organic materials and is more expensive. The synthetic fertilizer is called “quick-acting” because it lasts only about two weeks before it is used by the plants or drains down into the soil. The organic fertilizers are called “slow release” or “controlled release” because they last for 8 to 12 weeks which is most of the growing season.
Liquid fertilizers come in the same two categories – quick-acting synthetic and slow-release organic.
WE NEVER USE QUICK-ACTING SYNTHETIC FERTILIZERS ON OUR VEGETABLE GARDEN!!! NEVER!!
Year One and Two Fertilizing Program For A Vegetable Garden
Bed Preparation - When we prepare our beds in the spring, we usually do not know precisely where is type of vegetable is going to be planted. So while we are spreading a thin layer of compost on the beds we also sprinkle a few handfulls of granulated organic fertilizer very sparsely over the surface of the bed.
We get better results if we treat what are called “heavy feeders” differently from those “light feeders” in the vegetable world:
Heavy feeders - Cabbage, Broccoli, Cauliflower, Corn, Eggplant, Kohlrabi, Lettuce, Onions, Peppers, Potatoes, and Tomatoes
Light Feeders - Beans, Beets, Carrots, Peas, Cucumbers, and Swiss Chard
Simple Yardener’s Fertilizer Measuring System
One cup = a full handful spread over ten to twenty square feet of garden in spring soil prep
One cup = a full handful, good for 4 square feet of garden, for heavy feeders in spring
One half cup = a small handful, good for 4 square feet of garden for light feeders in the spring.
One quarter cup = less than a handful; for heavy feeders in mid-season
Optional Liquid Fertilizer Booster - A foliar application of liquid organic fertilizer (fish emulsion and/or kelp ) in June for all your veggies and again in late August will give the plants a boost, but this is an optional step.
Year Three and Beyond In The Vegetable Garden
As your garden soil becomes richer and healthier because of the annual addition of organic matter, the need for any fertilizer goes down. Maybe in year three you use only half as much fertilizer as used in the first year, and by year six you can stop fertilizing at all. The reason for this is the earthworms, the nitrifying bacteria, and many other soil creatures are producing more than 8 pounds of nitrogen per 1000 square feet of soil; more than any vegetable plant ever needs.