Q:When should I start my fall garden? A:Cool night temperatures and lighter winds often make fall the best time of the year for vegetable gardening. Planting must be timed to allow frost-sensitive plants to mature before frost. Vegetables that will tolerate frost can be grown and harvested even during times of mild fall frosts. Mid-August is the time for planting the following vegetables: •Frost-tender vegetables: bush beans, lima beans, cucumbers and summer squash. •Frost-tolerant vegetables: beets, broccoli, brussels sprouts, cabbage, Chinese cabbage, carrots, cauliflower, collards, Irish potatoes, leaf lettuce, radishes, rutabaga, Swiss chard and turnips. •Spinach and mustard should be planted in mid-September, when temperatures cool. Some vegetables do better when put out as transplants. These include broccoli, brussels sprouts, Chinese cabbage, cauliflower and leaf lettuce. Germinating seeds have small root systems, so you must check soil moisture daily. It is critical to maintain good soil moisture in the top 2 inches of the soil. To prevent crusting and cool the soil, cover seeds with vermiculite. You may also want to provide some afternoon shade with a shade cloth or a tilted board. Q:Can we grow fall potatoes in Oklahoma? A:If seed potatoes are available and space permits, potatoes are a desirable supplement to the fall and winter food supply. Yields are usually lower than from spring-planted potatoes, but proper storage is much easier to provide, and potato quality is excellent. The practice of using potatoes from the fresh produce counter for planting purposes is not recommended. This kind of material frequently does not produce adequate growth and is considerably lower in yield. One of the problems is getting a stand of plants early enough to produce a crop before fall frosts. This emphasizes the need to use matured, medium-to-large potatoes that require cutting into 1- or 1 1/2 -ounce seed pieces. Cut potatoes should be allowed to cure three to five days before planting, and they should be stored in cool (45 to 65 F) conditions during curing. The best time to plant seed pieces is from Aug. 1-15. To have a more favorable (cooler) soil at planting time, deep furrows may be opened in the late afternoon, seed pieces planted, covered with 2 inches of soil, watered and mulched with straw or other available organic material. This should provide more favorable conditions for growth. Space potato pieces 30 to 42 inches between rows and 10 inches to 16 inches within rows. Days to harvest will be 90 to 110, depending on variety. Bill Geer is director of the Oklahoma County Extension Service. His column addresses frequently asked horticulture questions. For more information, call 713-1125.