Fall is an excellent time to grow many vegetable crops in Indiana when the gardener can take advantage of cooler temperatures and more plentiful moisture. Many spring-planted crops, such as radishes, lettuce and spinach, tend to bolt (produce seed) and become bitter in response to long, hot summer days. Fall gardening helps extend your gardening season so that you can continue to harvest produce after earlier crops have faded.
Some vegetables, such as broccoli, cauliflower and Brussels sprouts, are better adapted to fall gardening since they produce best quality and flavor when they can mature during cooler weather. In Indiana, spring tends to heat up rather quickly. For many crops, insect and disease pests are not as much of a problem in fall plantings.
Many vegetable crops are well adapted to planting in late summer for a fall harvest. Use fast-maturing cultivars whenever possible to ensure a harvest before killing frost occurs. Check with your local garden centers for available plants and seed. Or if you order by mail, keep the fall garden in mind while planning your spring garden seeds and plants. Seeds of the cultivars you want may be out of stock by late summer.
To prepare your garden for a fall crop, remove all previous crop residues and any weed growth. Rototill or spade at least 6-8 inches deep. One to two pounds of a general analysis fertilizer, such as 12-12-12, may be applied per 100 square feet of bed area. Be sure to thoroughly mix the fertilizer with the soil.
Late summer plantings often suffer from hot soil and a lack of water. Soils may form a hard crust over the seeds, which can interfere with seed germination, particularly in heavy soils. Use a light mulch of vermiculite, compost or peat moss over the seed row to prevent a crust from forming. Seeds of lettuce, peas and spinach will not germinate well as soil temperature reaches 85 F and above. Shading the soil and using a light mulch over the seed row will help keep the temperature more favorable for germination. Planting the seeds slightly deeper than spring plantings also may be beneficial since temperatures will be slightly cooler and moisture more plentiful.
Do not allow seedlings and young transplants to dry out excessively. Apply 1 inch of water in a single application each week to thoroughly moisten the soil, if rainfall is inadequate. Young seedlings may need to be watered more often during the first week or two of growth. Young transplants may benefit from light shade for the first few days until their new roots become established.
Some vegetables that are already growing in the garden will continue to produce well into the fall, but are damaged by even a light frost. Some crops are considered semi-hardy and will withstand a light frost without protection. Others are hardy enough to withstand several hard frosts. Many common vegetables are listed in Table 1 according to their frost tolerance.
Indiana often enjoys several more weeks of good growing after the first frost. You can extend the fall growing season for tender crops by protecting them through early light frosts. Cover growing beds with blankets or throw-cloths supported by stakes or wire to prevent mechanical injury to the plants. Individual plants can be protected with such items as paper caps, milk jugs, plastic water-holding walls and other commercially available products. The season can be extended even further by planting crops in a cold frame or hot bed.
Table 1. Cold Temperature Tolerance of Vegetables
| Tender Vegetables | Semi-Hardy Vegetables | Hardy Vegetables |
| (damaged by light frost) | (tolerates light frost) | (tolerates hard frost) |
| Beans | Beets | Broccoli |
| Cucumber | Carrot | Brussels Sprouts |
| Eggplant | Cauliflower | Cabbage |
| Muskmelon | Celery | Collards |
| New Zealand Spinach | Chard | Kale |
| Okra | Chinese Cabbage | Kohlrabi |
| Pepper | Endive | Mustard Greens |
| Pumpkin | Lettuce | Onion |
| Squash | Parsnip | Parsley |
| Sweet Corn | Potato | Peas |
| Sweet Potato | Salsify | Radish |
| Tomato | Spinach | |
| Watermelon | Turnip |