The Edible Garden in July
We are entering July following a June that was hotter and drier than average. This has required more watering than usual and caused cool weather crops to bolt quickly. On the other hand the soil is warm, and heat-loving summer crops like squashes, melons, sweet potatoes, and eggplants are off to a good start. Flexibility in plant selection and planting timing is key to optimizing results given the weather’s unpredictability.
Planting and Harvesting
As you transition from spring to summer crops and later from summer to fall, be sure to maintain good soil hygiene by removing spent and diseased plant material. Prune and space plants to allow for good air circulation. Water at the base of plants, in the morning, and avoid splashing soil on plants. A light straw or leaf mulch can help prevent soil splashing while helping to conserve soil moisture if weather continues to be hot and dry.
If you planted cool weather crops in the early spring, they have likely completed their life cycles. This typically includes greens and cole crops, although, with luck, you may be harvesting the last of your broccoli and chard. Clean the garden of spent plants, perhaps leaving a few uneaten lettuces and herbs to flower, which will draw pollinators and beneficial insects to the garden. The removed plants can be composted if not diseased and if they haven’t set seed. Otherwise, it is best to dispose of them.
There is still time to plant summer vegetables including beans, okra, pumpkin, sweet potatoes, cucumbers, peppers, squash, corn, eggplant and tomatoes.
Late July into August is the time to make a fall planting of your favorite cool weather vegetables. Amend soils now by adding mature compost and organic fertilizer to the top couple of inches of soil to give soil life the time to make nutrients plant-accessible. Crops that can be planted at the end of July include broccoli, brussels sprouts, cabbage, carrots, cauliflower, collards, leeks, and rutabaga.
For a comprehensive listing of recommended planting times for your hardiness zone, refer to Extension Publication 426-331, Virginia’s Home Gardening and Vegetable Planting Guide.
Advice for Tomato Growers
Tomatoes are a prized summer crop for many of us. It is best to support plants with stakes or cages. If you use stakes (I use half inch rebar, but wood is commonly used), tie plants loosely to the stake with a soft twine or cloth strip. Add ties to give needed support as plants grow and fruits develop. Prune lower leaves that touch the ground to reduce susceptibility to soil pathogens. Allow up to two main stems and pinch off all other “suckers” that sprout at leaf/stem intersections to focus the plant on fruit production rather than vegetative growth.
Pinch off “suckers” where leaf and stem join to focus tomato plants on fruit production
Cages require more upfront investment and off-season storage space, but reduce plant maintenance time during the growing season. If you use cages, prune plants to 3 or 4 main stems. The additional vegetation will help protect fruit from sun scald.
In all cases, remove any diseased foliage quickly with shears disinfected with a 10% bleach solution. Best to bag and remove diseased vegetation with your trash. Mulching with straw helps maintain moisture, hold down weeds, and reduce soil splash during watering.
A more complete guide to growing tomatoes is provided in Extension Publication 426-418, titled “Tomatoes.”
Summer is the peak activity period for many garden pests. Here is some information about a few common ones:
Slugs: A run of wet weather in the summer tends to cause slugs to proliferate. Besides handpicking them where leaf damage signals their presence, improving air circulation by thinning heavy mulches and pruning and spacing plants can help manage them. Sprinkling diatomaceous earth or crushed egg shells around plant bases can create a barrier to slugs reaching plant stems. Toads are a natural predator, so creating a toad house nearby may also help. Other deterrents include placing a pan of beer with edge at soil level, inviting them to slither in and drown, or placing a partial melon rind upside down on the ground overnight, then collecting the rind and overstuffed slugs in the morning for disposal.
Striped cucumber beetle. Photo: Melissa McMasters, CC BY 2.0
Cucumber Beetles: Adult cucumber beetles emerge in late June/early July. Striped and spotted varieties can damage flowers, foliage, and roots of cucurbit family plants. They are also a vector for bacterial wilt disease. Control them with row covers, by hand picking, and good garden hygiene. For serious infestations, additional measures are outlined in Extension Publication 2808-1009, “Cucumber Beetles.”
Squash Bugs: Squash bug nymphs and adults can attack any cucurbit but prefer squashes and pumpkins. They pierce plant tissue and suck liquids out, while injecting a toxic substance into the plant that causes vines to wilt and die. A board on the ground near vines offers overnight shelter to the bugs which can be collected and dropped into soapy water in the morning. Maintaining good biodiversity can also help. The tachinid fly attacks squash bugs and can help control modest infestations. Details are available in NC State Extension Publication: “Lookout for Squash Bugs.”
Stink Bugs: Brown marmorated stink bugs will attack a variety of plants including tomatoes, peppers, beans, cucurbits and sweet corn. They suck liquids from leaves causing spots and wilting. Handpicking, good hygiene, and minimizing wood mulches can help control them. Companion planting with chives, onions, garlic, radishes, nasturtiums, marigolds, bee balm, and dill also deter infestations. Again, beneficial insects, namely the tachinid fly, prey on the bugs and are helpful. Tachinid flies are not available commercially, so build a diverse ecosystem around the garden to attract them.
Cabbage worms: During the past few years my gardens have had serious infestations of the larva of imported cabbage moths and cross-striped cabbage moths that have decimated my kale and collards. This year I protected them with a row cover in early May and am happy to report that the greens have grown well with virtually no damage. Because we are approaching fall planting time for these crops and since the moths and larvae are active until frost, this measure may be of interest if you have struggled with these pests. Simple and inexpensive row cover ideas are explained in the November 2019 Garden Shed article “Row Covers: A Season Extender with Benefits”.
If you want help identifying an insect, try the University of Georgia Extension video Garden Insects: Friend or Foe. A good source to determine treatments for identified pests is the Cornell Extension’s Resource Guide for Organic Insect and Disease Management.
Other ideas to help maintain garden health during July:
- Watering is extra important in the hotter months, for overall plant health, and for the taste and texture of many vegetables. The garden typically needs about an inch of water per week, more during very hot periods. Early morning is the best time to water. It’s cool so it minimizes evaporation and gives leaves time to dry before dark, reducing susceptibility to fungal diseases. Mulching with straw can stabilize soil moisture and help hold weeds down.
- As we become more sensitive to water as a critical resource in short supply, use of rain barrels is increasingly attractive. They can reduce runoff, conserve water resources, and reduce water/sewer bills. Natural rain water is also better for plants than chlorinated water. They are placed under downspouts. Rainwater passes through the downspout to a diverter that sends it to the barrel. When the barrel is full, the water is sent back down the downspout. Rain barrel water isn’t considered potable and can pick up pathogens from fecal matter on roofs, so should be applied to the base of plants, not sprayed on foliage. The benefits of rain barrels are discussed in the publication Rain Barrels from the Penn State Extension.
- It’s important to control weeds around vegetables because weeds can out-compete vegetable plants for nutrients, water, and sunlight. The best method of control is by mechanical extraction, meaning good old-fashioned weed-pulling or the use of a hoe. For small weeds, the “hoop” or “stirrup” hoe is highly recommended because it allows for shallow cultivation.
- Another plus for the hoop or stirrup hoe: it doesn’t bring weed seeds to the surface of the soil! Deep cultivation often brings seeds to the surface of the soil, facilitating germination of a new crop of unwanted weeds.
- Fusarium wilt of Basil is a fungal disease specific to sweet basil. The fungus attacks the water-conducting tissue (xylem) within the stem. Infected plants will grow normally until they are six to twelve inches tall. Then the plants suddenly wilt. The stem may become curved and develop brown streaks. The fungus can over-winter and survive many years as spores, ready to cause new infections in basil or other members of the mint family that are planted in the same soil. There is currently no fungicide approved for its treatment, but it can be controlled somewhat by removing diseased plants, by rotating planting locations, and by planting disease-resistant varieties. Additional information is available at edu/-fusariumbasil.
- Okra blossoms are one of the showiest blooms in the vegetable garden, but they only last one day. Keep an eye open for them if you don’t want to miss them. If the flower has been pollinated, a miniature okra pod can be seen beneath the wilted flower.
- Cucumbers develop a bitter taste if the soil is not kept consistently moist. Leaf mulch will help maintain soil moisture.
- Harvest cucumbers for pickling when they reach 2-4 inches in length; for table use, harvest when no longer than 5-6 inches. Remove over-ripe cucumbers to encourage continuous production.
- Withhold water on potatoes when the plants begin to die down. Water and fertilizer may disturb the dormancy stage and cause regrowth, and may also cause potatoes to crack.
- If you use insecticides on vegetables, always check the label to understand how much time you need to wait before safely harvesting and eating.
For more tips on a variety of gardening topics, check out the Monthly Gardening Tips listed on the PiedmontMasterGardeners.org website under Gardening Resources.
I hope you find this information helpful and look forward to sharing ideas again next month.
“Weeds in the Home Vegetable Garden,” Virginia Cooperative Extension Publication No. 426-364, pubs.ext.vt.edu/426/426-364
“Basil Problem,” NC Cooperative Extension. https://growingsmallfarms.ces.ncsu.edu/growingsmallfarms-fusariumbasil/