July 9, 2010

Vegetable Gardening, It Starts With The Soil

By Cindy Peacock, Extension Horticulturist

Properly preparing your garden plot soil will help you have a successful garden. You can grow a good garden wherever weeds will grow. Avoid low, poorly drained areas that stay soggy after rains.

Vegetables need full sun to grow, at least five hours of direct sunlight per day, so choose an area that is not shaded by trees or buildings. Once you have found a full sun, well drained area for your vegetable garden plot you can start preparing the soil. Our Florida soils are very sandy and are often low in nutrients. Adding organic material (manure, compost, leaves, grass, etc.) and fertilizer can greatly improve the soil.

First, pull or kill all the weeds in the garden area. You can hand pull weeds or use garden tools to remove them. A scuffle hoe works very well. You can also use a tarp or layers of newspaper to kill weeds. Lay the tarp or newspaper out over the weeds in the garden area and let it sit for about a week. When you lift up the tarp or newspaper the weeds will be yellow and dead. Another option is to use an herbicide that contains Glyphosate. This is a systemic herbicide. It is absorbed by the green plant tissue and taken down to the roots, killing the plant. Glyphosate has no residual activity.

Once the area is cleared, you can start adding organic materials. Compost (made at home or store bought), top soil, leaves or horse or cow manure can be added. Mix the organic material in well. You can also create a raised bed by mounding the organic material up or you can build sides out of wood or brick or other materials. Raised beds require less bending to maintain and they also improve drainage.

Our Florida soils contain microscopic organisms called nematodes. Some kinds of nematodes are beneficial but we also have a few species, like root-knot nematodes, that are harmful to the vegetables that we grow. Adding organic material to the soil in your vegetable garden plot will help to reduce problems with harmful nematodes.

It’s a good idea to have your soil tested to find out the pH of your soil and what nutrients are lacking. Soil pH, the acidity or alkalinity of the soil, is important because it governs how readily available nutrients are to plants. The pH chart below shows how soil pH affects the availability of individual plant nutrients. Vegetables grow best in a pH range of 5.5 to 7.0. If your soil is below 5.5 it is too acidic and you would need to use lime to raise the pH. If the pH is above 7.0 the soil is too alkaline. Applying sulfur will lower the pH in some situations. Adding lime or sulfur can harm your soil if you apply it without determining that it’s needed based on the results of a soil test.

The University of Florida Extension Soil Testing Laboratory can test your soil for a small fee. After testing the soil, the laboratory will send you a report including information on how to adjust your soil pH if needed. More information on the soil testing services can be found here:

To learn more about soil pH go to this website:
If you have to adjust your pH with lime or sulfur mix it into your plot.

After getting your soil ready for the fall, there should be enough time to enhance your soil even more. Here are some things that can help while you are waiting for September to plant.
One of the best ways to kill soil-borne pests is by soil solarization. This technique which uses the sun’s energy to heat the soil. When you are finished prepping the soil, moisten it and then cover the soil with sturdy, clear-plastic film. Make sure you seal the edges with mulch, wood or bricks to prevent the plastic from blowing off and to keep the heat in. Keep the plastic on for 6 weeks or longer.

Do not do any additional mixing of the soil after you have lifted the clear plastic. Plant right into the prepared plot. Mixing the soil after solarization will bring soil to the surface from deeper below where the solarization was less effective. This will defeat the purpose of the solarization that you worked hard to accomplish.

Another way to help keep the nematode population down is to plant your plot with marigolds. Marigolds produce a substance called alpha-terthienyl, which can aid in the reduction of root-knot nematodes and other disease promoting organisms, such as fungi, bacteria, insects and some viruses. African (Tagetes erecta) and French marigolds (T. patula) are the most commonly used species. For best results plant marigolds as a summer crop year after year.

For more information on marigolds for nematode management go to this web page

Growing a crop to later work into the soil to improve it is called “green manuring” and these crops are called “green manures.” Planting and plowing in green-manure crops during the off-season is beneficial to the soil, adding nutrients and compost to it.

Clear your plot at the end of the growing season, (usually beginning of June for most vegetable crops in our area) or if you’re just starting out to prepare your garden soil. Black-eyed peas are a good green manure for our area. You can plant black-eyed peas in rows about 18 inches apart. Let them grow up to about a foot or two. Before they go to seed cut them down and till them in. They will decompose in the soil for 6 weeks or more. Black-eyed peas (and other legumes) add nitrogen to the soil.

To learn more about soil preparation, composting and cover crops attend the Vegetable gardening class “It Start with Soil” July 17, 2010 at 9:00 at Pinellas County Extension. The cost is $15.00 per class. Pre-register on line on our Pinellas County Extension web site.

Other classes that will help you with Vegetable Gardening.

July 17, 2010 9:00 am “It Starts With Soil”

July 24, 2010 9:00 am “Planting, Setting and Growing”

July 31, 2010 9:00 am “Pest Identification and Harvesting”

August 7, 2010 9:00 am “ From Your Garden to Your Kitchen”

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