August in the Edible Garden

A hot summer with spotty rain has defined edible garden management issues this year. Good mulching and watering practices can help keep warm weather crops healthy longer while reducing the labor to maintain them. In my garden, the fungal diseases that cause trouble during moist years haven’t been much of a problem. Intensive planting and liberal use of leaf mulch has helped keep the soil shaded and minimized evaporative losses, but plants have still required more irrigation than normal. Nevertheless, I’m entering August with a pretty healthy vegetable patch.

Summer Crops

Watering, hygiene and harvest timing are key to extending yields on summer vegetables. The 1 inch of water per week rule is a good guide and being a bit more generous when it is really hot helps. 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 fruits before they reach full maturity to keep plants producing.

August is the peak of tomato season, a summer highlight for many of us. Depending on variety and planting timing, some determinate varieties may be presenting a full harvest now. Indeterminate varieties however 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.

I’m happy to report that I selected my tomato seeds carefully this year to find cultivars that are resistant to the blights that hurt my plants last year, and the results have been positive. Rotating tomato location in the garden may also have helped, but I’m entering august with the best looking tomato plants I can remember.

On the other hand the fruits have been slow to ripen. It seems like the green tomatoes don’t want to redden. The article Why Aren’t My Tomatoes Ripening, from the Cornell Extension, explains that at temperatures above 85 degrees the plants don’t produce the lycopene and carotene compounds that cause the reddish colors. We can take matters into our own hands however by picking tomatoes when the first blush of color change occurs, storing the green tomatoes at 70-75 degrees, 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 good news is that the taste compromise is minimal compared to fully vine ripened fruits. This is also a good way to protect tomatoes from invading varmints and to save late season fruits that may be threatened by frost.

If diseases are a problem find help in identifying and addressing them in  two articles from the Missouri Botanical Garden. The article Tomato Fruit Problems is helpful in identifying tomato diseases and Tomato Diseases and Disorders offers information for disease prevention and control. Also, note specific diseases you confront to guide you toward resistant seed and plant selections next year.

Tomato hornworm hosting parasitic wasp cocoons: Photo: R Morini

Pests can also hurt tomato harvest. Tomato hornworms are a common one. The key sign on their presence is denuded leaf stems. If you see one that looks like the one 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 when 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.

Tomato thief: Photo Ralph Morini

Mammals can also be tomato pests as the photo shows. Squirrels and chipmunks are more problematic than dogs for most gardeners. My best suggestion for keeping them at bay is wrapping netting around plants, being careful to tie top and bottom openings closed. Other possibilities include interspersing scented plants like mint in the vicinity, placing coffee grounds around the plant base and making sure other food sources, like bird feeders, are not near the garden.

Planting a fall crop

August is the time to plant fall crops. In Hardiness Zone 7a, the first frost is expected in the October 15-25 time period, roughly 70-80 days from August 1. When choosing seeds to plant, be conscious of time-to-harvest noted on the seed packs to be sure the crop has adequate time to mature prior to frost. Cool weather crops, including greens and cole crops, survive frost but growth will slow down as days shorten and temperatures cool. Getting them to a harvestable stage prior to frost is a good idea. In general, choosing varieties with a short time to maturity makes sense.

Per the VA Cooperative Extension publication Virginia’s Home Garden Vegetable Planting Guide, now is the time to plant transplants of broccoli, cabbage, cauliflower, collards, kale, kohlrabi and mustard, while planting seeds for beets, carrots, lettuce, radish, spinach and turnips.

The fall gardening season can be very productive here in central VA. We can enjoy home-grown produce at least through frost, and many greens and cool weather crops remain harvestable well into winter if established prior to cold weather’s arrival. 

More Gardening Tips and Tasks For August:

• When choosing vegetables for the fall garden, check seed packets or catalog and select semi-hardy varieties that will tolerate a light to moderate frost and look for those requiring fewest days to harvest.
• Fall plants often have fewer insect problems because they avoid the peak insect activity period 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 planting crops of different families than those grown in that garden section earlier in this growing season.
• When planting fall crops, prepare the soil by restoring the nutrients removed by spring and summer crops. A light layer of compost or application of a balanced organic fertilizer will provide the nutrients needed by fall crops.
• Dry soil can make working the soil difficult and can also inhibit seed germination during the late summer. 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 all 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 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.
• When mulching around young seedlings, take care not to cover them.  Young seedlings need as much sunlight as possible. Mulch should cover the soil, not the plants.

Cross striped cabbage worm on kale: Photo: R Morini

• 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 and  pick worms off the plants when you see evidence of chewing or excrement on the plants. For extreme infestations, use Bacillus Thuringiensis (Bt), an organic and relatively safe 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.
• Potatoes continue to grow as long as the tops are green. Dig only as many as you need for immediate use. The tubers will keep better in the ground than in a warm, dry area.
• Garden vegetables that become over-ripe are easy targets for some pests. Remove ripe vegetables as soon as possible.
• When harvesting, don’t let your produce sit in the hot sun. Cover, or even better, keep them cool, to prevent loss of succulence, wilting, and conversion of natural sugars to starch.

Hang in There

It’s easy for vegetable gardeners to begin to slack off in August. The spring plants have expired, we’ve been fighting 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 in The Garden Shed. We look forward to sharing experiences 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/programs/horticulture-natural-resources.html

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: R Morini