Fall gardening season has arrived

Monday, August 19, 2013

Although Oklahoma gardeners are still reaping the rewards of their spring gardens, the time has arrived to start the fall gardening process.

David Hillock, Oklahoma State University Cooperative Extension consumer horticulturist, said some of the best quality garden vegetables are grown during the fall season.

“Successful fall gardening begins much earlier than the fall season. High-quality results are available during the fall when warm, sunny days are followed by cool, humid nights,” Hillock said. “Under these climatic conditions, plant soil metabolism is low; therefore, more of the food manufactured by the plant becomes a high-quality vegetable product.”

Although much of Oklahoma has received a lot of rain recently, climatic conditions in August typically involve high soil temperature, high light intensity and rapid drying of the soil. This can result in difficulty obtaining a uniform stand of plants. With lower than normal temperatures, gardeners may not have to use special treatments such as shade over rows when seeded and supplemental watering to reduce soil temperature.

Hillock said in order to germinate or sprout, the seeds must be viable, have proper temperature, adequate moisture and sufficient oxygen.

“The surface of the soil, when exposed to the summer sun, may become very hot (140°F or 60°C).  Vegetable seeds should be planted no deeper than three times the diameter of the seed,” he said. “With small seed such as carrot, this would be no more than 1/4 inch deep. At this depth and exposed in the hot soil, death of the seed due to high temperature would probably occur. It’s also likely that such a soil, even when watered, might dry out quickly because of the high temperature. Unless the soil remains moist at the depth where the seeds have been planted, germination will not take place.”

In order to achieve proper temperature and adequate moisture, apply mulch over the row following planting and watering or use materials such as screen wire strips, shade cloth or boards to cover the row.  This will moderate both soil temperature and soil moisture. Remove covers after seedling emerges.  

Hillock said broccoli, cauliflower, Chinese cabbage, leaf lettuce, Brussels sprouts and cabbage do well by planting seeds in a small seed flat, setting them in individual containers to grow for about a month, then transplanting to the garden.

"Prior to setting them in the garden, transplants may be conditioned or toughened by a reduction in the amount of water supplied and by exposure to full sunlight,” he said. “This might require three to five days. Plant them in the garden in late afternoon to early evening to reduce transplanting shock. As they are set, water the plants using a starter solution.”

 For more in-depth information about fall gardening, check out OSU Cooperative Extension Fact Sheet HLA-6009 at osufacts.okstate.edu and key in fall gardening in the search tool.