Gardening Help FAQs

Here are answers to some of the most common questions we receive about garden plants. You will find concise information on general gardening techniques as well as plant selection and care. For detailed information on specific plant pests and problems refer to our Common Garden Pests and Problems page.

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Horticulture Questions and Answers

What vegetables can I plant for fall harvest?

For many gardeners, fall signals the end of another growing season. More and more gardeners, however, are discovering that with a little planning and attention to certain details, gardens can be kept productive and full of fresh produce all the way to the first frost and sometimes even later.

For success with fall vegetables, always choose fast-maturing varieties which will produce a harvestable crop within 50 to 65 days. "Days to maturity" information is usually included on the back of the seed packet or in the catalog descriptions for varieties that were obtained by mail order. This information is important for setting up a timetable to figure when to sow the seeds of individual varieties. The key to fall gardening which spells the difference between success or failure is to time plantings so that crops are just maturing around the first fall frost date. In the St. Louis area, this date averages about October 20, give or take a week or so. For crops that are directly seeded into the garden, take the days to maturity and to this add one week to allow for germination. To this total you also have to add an additional two weeks for the " short-day" factor. This is necessary because crops always take longer to mature in the shorter days and cooler temperatures of autumn. For plants such as broccoli, cabbage and cauliflower, which are typically set into the garden as transplants, you also have to add an additional three weeks to raise them to transplant size first. Tally up all these days and subtract their total number from the first frost date of October 20. This will give you the latest date to sow individual varieties to ensure a fall harvest.

It is important to prepare planting sites to ensure a quick start for each crop. Loosen the soil, dig in a generous amount of compost, manure or other organic amendments to improve soil texture, and also work in some additional fertilizer. This will make up for the nutrients depleted by any previous spring crops. Use a fertilizer such as 12-12-12, applied at a rate of one-half to one pound per 100 square feet, and work it into the top 3 to 5 inches of the soil.

Seeds sprout reluctantly when soils are hot and dry. To overcome this, water the planting site a day or so before you sow seeds to ensure moisture for quick germination. Sow your seeds slightly deeper than you would in cool soils, water well with a gentle spray, and then cover the seeds with burlap, old wooden boards, wet newspaper or fabric scraps. These serve to keep the soil moist and prevent heavy rains from washing the seeds away. Check your seeds daily and remove the covers as soon as they start to grow. Some crops such as lettuce and spinach may sprout better if the seeds are cooled in the refrigerator for several days before planting. Once the plants are up and growing, timely watering during dry spells will maintain vigorous growth and avoid setbacks which may delay or prevent harvests.

By August 15 there are approximately 9 weeks left before frost can be expected. This leaves plenty of time for several sowings of loose-leaf lettuces and spring radishes. There also is just enough time for a single planting each of turnips, kohlrabi, winter radishes, spinach, mustard, swiss chard and chinese cabbage.

When frost inevitably threatens to end the gardening season, do not give up without a fight. Try mulching and covering tender plants to shield them from frost damage. Hardy cool-season vegetables are not bothered by light frosts, but may be mulched with loose straw or leaves just to be on the safe side.