August is busy in the edible garden as we enjoy harvesting summer vegetables while making new plantings of fall crops. As noted in Virginia’s Home Vegetable Garden Planting Guide, August is harvest time for beans, cucumbers, eggplant, melons, okra, onions, peppers, potatoes, squash, corn and tomatoes. At the same time, we can plant beets, broccoli, brussels sprouts, cabbage, carrots, cauliflower, many greens, lettuce, radishes, rutabaga, squash and turnips. When planting, remember that the warming climate has changed the VA Piedmont’s Hardiness Zone from 7a to 7b, which changes our average first frost date from October 15 to 25 to October 25 to November 5. So for fall crops, consider the time from planting to harvest, and plant early enough to minimize frost damage risk.
Summer Crops
Watering, hygiene, and harvest timing are key to extending yields of summer vegetables. The 1 inch of water per week rule is a good guide. Be more generous when it is really hot and dry. Insert a finger in the soil a couple of inches to test moisture if in doubt. Deeper, less frequent watering is more effective than frequent light watering, since the moisture will penetrate further into the soil where the plant roots are growing. Removing diseased and damaged vegetation from the garden and keeping garden tools disinfected is also essential. Since a plant’s job is done when it has created viable seed, pick vegetables before they reach full maturity to keep plants producing.
August is the peak of tomato season.
Depending on variety and planting timing, determinate tomato varieties may be presenting a full harvest now. Indeterminate plants can be kept productive until frost with good care. Pull off suckers, trim diseased leaves with disinfected tools, give a small fertilization boost if you haven’t amended the soil since planting, and keep them well watered.
If your tomato plants have yellow, spotted, or brown patches on leaves, they may have nutritional deficiencies or one of a variety of diseases. General advice is to remove discolored leaves with a disinfected shears, then bag, and trash the diseased foliage. For help in identifying and treating possible causes, check out The Garden Shed article Tomato Diseases.
If the fruits are slow to ripen, the article Why Aren’t My Tomatoes Ripening, from the Cornell Extension, explains why. At temperatures above 85° the plants don’t produce the lycopene and carotene compounds that cause the reddish color. We can influence ripening by picking tomatoes when the first blush of color change occurs, storing them at 70-75° in a dark, enclosed environment (I use a paper bag), and maybe adding other fruit, like bananas, to generate the ethylene gas that causes ripening to happen. The taste compromise is minimal compared to vine-ripened fruits. This is also a good way to protect tomatoes from invading varmints and to save late-season fruits that are threatened by frost.
If fruit damage is the issue, get help identifying the problem from the Missouri Botanical Garden article Tomato Fruit Problems. Good guidance on managing blossom end rot is provided by the Wisconsin Extension article Blossom End Rot. Record identified problems in your journal so that next spring you can look for seeds or transplants that are resistant to the diseases identified and note care advice that can help with nutritional or moisture-related issues.
Managing Pest Issues
Pests can also hurt your tomato harvest. Tomato hornworms are a common one. The key sign of their presence is denuded leaf stems. Pick and squish if you find a clean caterpillar. If it looks like the hornworm in the photo, leave it alone. The white cylinders on its back are beneficial braconid wasp cocoons. The adult wasp injects eggs into the hornworm. Larva feed on the worm’s innards until ready to pupate, and then they exit and spin cocoons as shown. Tiny adult wasps emerge a short time later. The hornworm may live through the wasp cycle but will die before pupating.
A variety of other pests can attack our gardens in August. The Garden Shed article Eleven Common Garden Pests: Identification and Management can help identify specific pests and treatments.
Building a diverse ecology in the yard and garden is step one for creating a natural pest control system. I’ve been working over the past few years to add pollinator plantings, end chemical use, rotate crops, interplant, etc. Reduced damage done by Japanese beetles and cabbage worms, previously extensive, has been significantly lower. I attribute this to larger beneficial insect and bird populations on the property which contains numerous native trees, including “keystone” white oak trees. Increasing biodiversity can definitely help reduce pest invasions.
More Gardening Tips and Tasks for August:
- When choosing vegetables for the fall garden, check seed packets or catalogs, and select semi-hardy varieties that will tolerate a light frost and require fewest days to harvest.
- Fall plants often have fewer insect problems because they avoid the peak insect activity of midsummer. However, some insects, such as cabbage worms and corn earworms, may be worse later in the year than in the summer. Avoid some pests and diseases by rotating crop families to different bed areas than those where they were planted in the spring.
- When planting fall crops, prepare the soil by restoring the nutrients removed by spring and summer crops. A well-tended spring compost batch should be ready to be screened and spread on beds with a light application of a balanced organic fertilizer to replenish soil for fall crops.
- Dry soil can make working the soil difficult and inhibit seed germination. Plant fall vegetables when the soil is moist, either after a rain or after you’ve watered the area the day before planting. Plant the seeds slightly deeper than recommended for spring planting. Once planted, water them thoroughly.
- Watering properly is the key to conserving water and maintaining plant health in the heat of the late summer. One inch per week applied at one time will wet the soil 6 to 8 inches deep and ensure good yield from mature crops. Two inches of organic mulch such as chopped leaves or straw will cool the soil and reduce surface evaporation. Water the garden early in the day so the foliage dries before nightfall. Wet foliage at night increases susceptibility to fungal diseases.
- If you have a problem with cabbage worms on your cole crops (cabbage, kale, collards, broccoli, cauliflower, brussels sprouts), consider using floating or hoop-supported row covers. The Garden Shed article Row Covers: A Garden Season Extender with Benefits offers “how-to” advice. Pick worms off the plants when you see evidence of chewing or excrement on the plants. For extreme infestations, use Bacillus Thuringiensis (Bt), a relatively safe organic pesticide as per label directions. If you protect your plants until the first frost, you can enjoy harvesting many of these vegetables well into winter. For more detailed info on the problem and solutions, refer to The Garden Shed article OMG, What’s Eating the Broccoli.
- If vining crops like squash and pumpkins are taking up too much of your garden space, it’s ok to pinch off the growing tips. This causes the plant to put more energy into fruit maturity, less into vegetative growth.
- Harvest potatoes when the vines turn completely brown. Brush dirt off tubers when harvesting and don’t wash until just before use. Cure for a couple of weeks in a cool, dark place to allow skins to harden. If tubers are damaged when harvesting, use them immediately since they tend to spoil quickly. Also, cut away any green parts of potatoes since they are bitter and can cause gastric distress if a large amount is eaten. More info is available from the article Homegrown Potatoes Tell You When to Harvest Them by the Michigan State Extension.
- If you have never investigated corn pollination (hint: every tassel has to be pollinated by at least one pollen grain to create a fully kernelled ear), find an interesting explanation in the article The Corn Pollination Process from the Wayne County OSU Extension.
- Bulbing onions should be harvested when half their leaves are dried and fall to the ground. Harvest when soil is dry to minimize disease susceptibility. Allow them to cure for a few days. Remove dirt, cut off tops within 1-3” of the bulb, trim the roots, and leave the outer skin in place. Store them in a cool dry place.
- Garden vegetables that become over-ripe are easy targets for some pests. Remove ripe vegetables promptly.
- When harvesting, don’t let your produce sit in the hot sun. Cover, or even better, keep them cool, to prevent wilting, loss of succulence, and conversion of natural sugars to starch.
Hang in There
It’s easy for gardeners to slack off in August. Spring plants have expired, we’ve been fighting both pests and the weather all summer, and we’re hot and tired. But if we stick it out, fall gardening can be really rewarding. Refresh the soil, plant the fall crops you enjoy the most, and you’ll be able to have fresh garden produce well into, if not through, the winter.
Thanks for visiting us at The Garden Shed. I hope to talk again next month.
Sources:
Monthly Gardening Tips, PMG Website: https://piedmontmastergardeners.org/gardening-questions/monthly-gardening-tips/#August
“August Monthly Tip Sheets -Vegetables,” https://albemarle.ext.vt.edu/content/dam/albemarle_ext_vt_edu/files/hort-tip-sheets/8-14-vegetables.pdf
Monthly Tips and Tasks, Missouri Botanical Garden: https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/gardening-by-month/august.aspx
Feature photo: Piedmont Master Gardeners Cleve and Fern Campbell’s vegetable garden in August by R. Morini
