If you have raised bed gardens that you use to grow fall and winter flowers and/or vegetables, it is time to make preparations so that you can be ready to plant in September.
Two essential ingredients for a successful cool weather garden are compost and mulch.
Compost is the basic soil enrichment additive. Incorporate 2 to 4 inches of compost (decomposed organic material) into your raised bed and it becomes better drained, better able to hold water, and more nutrient efficient. Compost is able to both increase water holding capacity and drainage because it creates channels of varying size in the soil. Large diameter channels allow water to move deeper into the soil reservoir and create air pockets where roots can find oxygen. At the same time smaller channels are formed that are the perfect size to hold molecules of water that can be extracted by the root hairs.
The compost in the soil must be replenished every year or two because in our hot climate the decomposition that began in the compost pile, continues until all the organic material is broken down to gases and basic molecules that are used by the plant or dissipate into the air.
Mulch is the material that insulates the soil with the result that evaporation is reduced and the soil temperature stays cooler. Rock and other non-organic materials can work as a mulch but usually we use we use an organic material such as leaves, shredded brush, bark or pecan shells. Organic mulch will eventually decompose to make compost but in the absence of high levels of nitrogen (green plant materials) it usually takes several years.
Use finer materials such as leaves and double chopped brush as mulch for flowers and vegetable plantings (2 inches deep). Coarser materials work well for newly planted shrubs and trees (4 inches deep).
To supplement the mulch and compost that you can produce in your own compost pile or by leaf raking, buy it in bags at your favorite nursery or in larger supplies at the several horticultural supply suppliers we have in the area. Fill your pick-up truck at Quality Organic, Keller Material, Fertile Garden Supply, New Earth, GardenVille or other suppliers. They will also deliver the materials you need for a successful fall gardening season to your site.
Dr. Calvin Finch is Urban Water Program Director for the Texas A&M Institute of Renewable Natural Resources. You can ask Calvin question and hear his answers on the air as he co-hosts the Gardening South Texas on the air at KLUP (AM 930) Saturday and Sunday from 12:00 to 2:00pm.