Bob Westerfield is extension horticulture specialist for University of Georgia. Adrianne Todd is Bob’s technical assistant working at the Griffin campus.

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Winter Garden Crash Course
by Bob Westerfield       #Edibles   #Vegetables   #Winter

By now, many gardeners have planted their winter gardens and are already harvesting tender broccoli, fresh cabbage and lettuces. If you live in the warmer areas of the Southern states, there’s still time to get seeded crops into the ground. Parts of Louisiana, Florida, southern Texas and southern Georgia can still grow from seed. Areas farther north can still plant gardens using transplants and be reasonably assured of a harvest before extreme winter temperatures arrive. Growing a winter garden is very similar to growing a spring garden, however, winter vegetables prefer warm soils in the beginning and require cooler temperatures to develop and mature. By following a few simple guidelines, you can ensure a successful winter garden.

If you haven’t done so already, it’s a good idea to conduct a soil test to determine the actual nutrient levels of your garden. The pH level of the soil is the most critical information in the report and should be adjusted to a range of 6.2 to 6.8. Spent summer vegetables should be removed and added to the compost pile, freeing space in the garden to till and plant new crops. If temperatures are extremely mild and you live in the southernmost areas of the Southern states, you can still direct-seed vegetables such as lettuce, greens, carrots and radishes. When planting lettuce seed, firm the seedbed and lightly tap the seed down into the soil, but do not cover it. Lettuce seed needs ample sunlight for good germination. Keep in mind that buying and planting healthy transplants may be the safest route to go this time of year.

Lettuce thrives in cool temperatures and does especially well in raised beds. Leaf and Romaine types are best suited for Southern climates.

Warm temperatures can cause broccoli to bolt and bloom prematurely prior to harvest.

Scout your fall garden frequently, looking for any insects or disease that may have invaded your crop. Harvest your crop as soon as it is large enough to pick.

When it comes to growing winter vegetables, the biggest challenge arises when temperatures range from very warm to extremely cold virtually overnight. I’ve already had problems with the lettuce in my winter garden this year, when warmer-than-usual days caused the lettuce to bolt. Insect invasions are another common problem in the winter garden. Although many summer pests have begun to subside, some may still be present, including whiteflies and aphids. Cabbage looper is another pesky insect that loves to tunnel through cabbage, broccoli and other greens. Snails and slugs may also appear on warmer evenings and create holes in your plants. When it comes to control, early detection is key. Monitor plants regularly to spot the first signs of trouble. Bt and Dipel are both organic products that work very well to control caterpillar-type insects, such as loopers. Other insects can be chased off or killed with pyrethins, safer soap or mild insecticides. Fast control is essential to catch insects before they tunnel deeply into plants. Caterpillars that burrow deeply inside of a cabbage head will be heavily protected by its leaves and may not be affected by insecticides.  

Diseases can also be an issue in the winter garden, but usually less so than during the summer months. While not very common, foliar diseases, root rots and potential viruses may still affect the winter garden if gardeners are not careful. Many diseases are caused by poor cultural practices. Mulching around plants with pine straw, wheat straw or wood chips can prevent plants from being splashed by disease-bearing soil. A few inches of mulch will also help reduce winter weeds and moderate root temperatures. In my trial garden, half of the broccoli and cabbage is mulched with wheat straw and the other half is un-mulched. The mulched crops appear to be much healthier and the vegetables are much larger than the un-mulched stand. Irrigation practices can also influence the potential for disease. When possible, use soaker hoses or drip irrigation to water all winter vegetables. Overhead irrigation with a sprinkler will wet the foliage and make vegetables more susceptible to disease. Overhead irrigation also wets much of the non-target area and encourages excess weed growth while wasting water. When it comes to watering, it is often believed that cooler temperatures mean that plants no longer need supplemental irrigation — but this is not the case. Vegetables in the winter garden still need an occasional 1 to 1½ inches of water to obtain optimum growth. Containers and raised beds may need more frequent watering because they tend to lose water quickly and dry out.

Limited space should not stop anyone from planting a winter garden. Containers and window boxes can make an excellent place to grow your favorite cool-season veggies!

Carrots are an excellent cool-season vegetable that enjoys soft, well-amended soils. Hard, red clay soil will cause carrots to stunt and make it difficult for them to reach full size.

Clover, such as this red flowing variety, makes an excellent cover crop in the fall to help build and protect the soil in idle areas of the garden. Clover can be planted as a stand-alone cover crop or mixed with cereal.

One of the final components of managing your winter garden is providing proper nutrition to plants. While a soil sample conducted through your county extension office will provide the proper fertility recipe for success, many gardeners choose to wing it and fertilize without testing. If you choose this route, it’s best to keep it simple. Leafy green vegetables require more nitrogen than winter peas, carrots or even broccoli. In the absence of a soil sample, I would fertilize with a premium fertilizer that contains micronutrients as the initial feeding at planting. When the crop begins to form a tiny vegetable, fertilize with a product such as 12-4-8. Be careful not to overfeed your plants, which will cause excessive growth and lower vegetable yields. Some vegetables, such as greens and broccoli, can be harvested again after the initial harvest. Additional fertilization every three to five weeks will help to ensure healthy harvests.  

For areas of the garden that you have chosen not to plant with winter vegetables, consider planting a cover crop rather than leaving the area barren. Cover crops are often called “green manure” and are essentially green plants that help prevent erosion and provide nutrients when tilled into the soil. Cover crops are also more aesthetically pleasing than bare soil or dead plants. I prefer a winter-crop mix of a cereal grain, such as wheat, rye or oats, mixed with a legume, such as winter peas or clover. Avoid planting ryegrass, which will be difficult to eradicate in the spring. Cover crops should be fertilized at planting time and maybe once again later in the season to give them a boost. 

Although winter gardening has its challenges, it’s also one of the most pleasant times of year to be out in the garden. While you can certainly purchase all of these crops at the grocery store, there’s simply nothing like harvesting fresh vegetables from the garden and cooking them the same evening. The satisfaction and flavor is unlike anything you can purchase from the store.

Photos courtesy of Bob Westerfield.


Posted: 10/15/12   RSS | Print


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