Weekly Express-News Article

By Calvin R. Finch, PhD, SAWS Water Resources Director, and Horticulturist

Saturday, February 2, 2008

“Vegetable Garden”

            February is a good month to begin vegetable gardening in the San Antonio area.  We have an opportunity to make a planting of cool weather vegetables that can be harvested through June.  Plant broccoli, cabbage, spinach, and chard transplants now.  Plant carrot, beet, radish, English pea, rutabaga, lettuce, and turnip seeds.  Potatoes can also be planted.  In six – eight weeks the warm weather vegetables can be planted.  Green bean seeds can be planted about March 15.  Tomato transplants can be planted in early April.  Plant peppers, okra, and southern peas in late April. 

            If you are considering a vegetable garden for the first time, the recommended way to raise vegetables is in a raised bed.  Use used railroad ties for the border.  Cement blocks, cedar lumber, treated lumber, plastic lumber, and rock all work as well.  The rock and cement blocks work best if they are mortared together, but it is not absolutely necessary.

            The railroad ties only need to be one tie high, but can be built two or even three timbers tall.  The tall beds are especially desirable for gardeners who work from a wheel chair or have trouble bending over.  A bed that is only one timber tall does not require that the timbers be fastened.  They are heavy enough to stay put if the soil is leveled under the railroad tie.  The best fastening system seems to be to drill holes in the ties and use a cut piece of 3/8 or ½ inch rebar cut to the thickness of the ties (one, two or three tall) with an extra foot of rebar that can be pounded into the ground to securely hold the structure in place.   

            It takes about two cubic yards of landscape mix to fill an eight foot by eight foot bed one railroad tie tall.  Add two cubic yards of soil for each eight foot section that is added to the original section and add two cubic yards for each additional layer in the air.  An eight foot by 24 foot garden would require six cubic yards of soil mix.  A bed with the same dimensions, three timbers tall would require 18 cubic yards of mix.  An eight foot by 24 vegetable garden is a good size for a small family. 

            A soil mix with one-third compost, one-third washed sand and one-third native soil works well.  It is easiest to buy it.  The landscape light soil sold at horticultural supply retailers such as Keller Material, Fertile Garden Supply or Garden Ville has about 50% compost.  It works well.  Expect to refresh and replenish the bed with compost every two years as the original organic material decomposes. 

            Vegetables are not xeriscape plants.  To maximize yields you do have to irrigate every few days.  The best irrigation system for a raised bed vegetable garden is a drip system.  Lines are laid along the row with emitters every foot or some other interval.  Drip systems are very efficient; they place the water at the base of the plant with almost no loss to evaporation or wind.  The home improvement stores and retail nurseries have drip irrigation kits or you can ask an irrigation company to put one in for you.  The kits are easy to do and are very inexpensive. 

            To make your watering even more efficient, mulch the vegetables.  Live oak leaves are my favorite mulch.  They are easy to work with and eventually decompose with minimal nitrogen deficit.

            Fertilize the vegetable garden with slow release lawn fertilizer before planting.  One cup per 50 square feet is a good amount.  Sidedress the vegetables every month with a cup per eight foot row.  Onions, greens and tomatoes are especially hungry for nutrients.  Root crops require slightly less fertilizer.