Your Veggie Garden in July

Our Garden Department is busy diagnosing a variety of vegetable garden ailments this time of year! Read ahead for common issues you may be experiencing in your gardens right now.  

Cucurbits 

Cucumbers and squashes are susceptible to powdery mildew. This fungus begins and spreads most readily with humid air and little rainfall. Powdery mildew can lead to defoliation, sunscald, and stunted fruit. 

What to do: Treat with a fungicide such as copper or sulfur. Biofungicides (such as Revitalize by Bonide, or BioRemedy) can act as a preventative as well as a treatment.  

Powdery mildew on my squash plants, late August 2025. 

When growing squashes, you may encounter the dreaded squash vine borer. Vine borer damage can appear overnight! Leaves wilt dramatically and you will notice a crusty yellow-orange substance on the vine, called “frass”. 

What to do: Despite what you read online, there is little to nothing you can do to prevent or combat the vine borer, which is the grub-like larval form of a species of moth. The moth lays single poppy seed sized red eggs anywhere on the plant’s leaves or stem. Once hatched, the insect bores directly into the plant and travels down the hollow leaf stem into the main stem of the plant. Monitor your plants, cut into the affected area, and try to locate and remove the borer. Otherwise, don’t stress – time to start some new plants from seed! 

At the risk of this post becoming very bug oriented, it is worth mentioning the cucumber beetle. If your cucumber plants are severely wilted, this is caused by bacterial wilt, which is transmitted by this beetle. It can also affect squash. 

What to do: There is no cure for bacterial blight and affected plants must be removed. Insecticides are not effective at combatting this bug; hand pick any that you see by knocking them into a bucket of soapy water where they will deteriorate.  

Credit: UMass Extension 

Brassicas 

Broccoli, cabbages, and brussels sprouts mature in cooler temperatures, so you may be noticing a halt in their growth and/or bolting (also with lettuces). This is also the season for the cabbage worm, the eggs for which are laid by that little white butterfly you see flitting around. 

What to do: Stagnant plants can be left through the fall to develop cabbage heads in cooler temperatures – in the meantime you can cook and enjoy the leaves! Start new broccoli plants from seed now. Cabbage worms can be combatted with BT (bacillus thuringiensis). Soak your harvest in a salt bath to get rid of any worms. 

Your kales are probably enjoyed more by bugs than by you at the moment…  

What to do: Embrace the joys of home gardening and harvest the kale anyway! Or leave the plant as a summer bug buffet, remove thoroughly damaged leaves near the end of August, and let the plant grow new leaves in the Fall when the temperatures are cooler and the bugs are less rampant. You can also start new plants from seed now. 

My curly kale stood above the rest of the garden by the end of August last year. 

Tomatoes 

The most common issue asked of our staff here at Country Garden in regards to tomatoes is about blossom end rot.  

What to do: If your tomatoes are planted in the ground, the cause is not a calcium deficiency, despite popular belief. Rather, it is the plant’s ability to take up calcium that has been impacted. Usually, blossom end rot can be prevented and corrected by adjusting your watering practices. Plants do best when watered deeply and infrequently: 2 or 3 times a week for at least 30 minutes. Drip irrigation and soaker hoses really come in handy here! 

If your tomato is planted in a pot or raised bed, the likely cause of blossom end rot is not enough soil or inconsistent watering. Each tomato plant needs at least 5 gallons of soil to thrive and produce happy fruit, and watered even twice daily in the heat of summer. When a potted plant with plenty of soil and proper watering is still producing fruits with blossom end rot, this may be a true case of calcium deficiency. Rot Stop, a foliar calcium supplement, will do the trick quickly.  

Note: Affected fruit can still be enjoyed – just cut off the brown part! 

Credit: Old Farmer’s Almanac 

Herbs 

Keep harvesting those herbs! The more you harvest, the more you’ll get. Use clean sharp pruners to chop height off of basil, oregano, rosemary, lemon balm, and more. This will encourage tidier, bushier growth habits and more tender young leaves. Most flowers from bolting herbs are also edible or useful in teas. If your herbs are looking bug eaten or sunburnt, that is all the more reason to prune your plants. Try drying or freezing herbs for year-round use or making a two…or three…or four-leaf pesto! 

Lastly – what’s eating your dill, fennel, and parsley? Say hello to the swallowtail caterpillars! 

Credit: iNaturalist