Long Island Horticultural Society

What's Going on in the Garden

August To Do List

Pick your spots to work outside. Anticipate heat waves and humidity, and get your work done on the days most pleasant for working outdoors. Prime garden chores are watering, harvesting and deadheading. 

Keeping plants well watered is of primary concern now in the heat. Some containers especially small ones might need watering twice a day. You can add mulch to your containers to cut down on water loss. Never use a liquid feed on dry plants; water them with plain water first.

Collect ripened seed and store for next year. Leaving some seed heads in place can be attractive and allows the plant to self-seed in the surrounding soil.


Water camellias and rhododendrons thoroughly this month to make sure that next year's buds develop well.

Be on high alert for insect pests. We didn't have a very cold winter in 2019 so insects will be more abundant this year. These include but are not limited to thrips, tomato fruitworm, tomato hornworm, spider mites, chinch bugs, scale, snails, and slugs.


The heat and humidity of mid-summer bring with them plant diseases. Inspect your plants for any diseased foliage now, remove it, and dispose of it properly (do not put it in the compost pile).

This is still prime time for heat-resistant plants such as coleus, hibiscus, Melampodium, Pentas, plumbago, moss rose, and zinnias.

Veggies: Keep up with your harvesting. Zucchini produce like crazy and get tough if left on the vine too long. Share the abundence with neighbors and/or Donate to local food banks. Ampleharvest.org lists local food banks in your area. Failure to harvest can also slow garden plants down. Late August sow peas, lettuces, kale and other cool season veggies for fall crop.

Flowers: Start dividing your bearded iris, remember when replanting do not plant too deep! Avoid pruning shrubs after mid-August. Cut back salvia, Coreopsis, and border phlox and they may rebloom.

Tips: To prolong the life of a hose, don’t leave it lying in hot sun. Treat perennial weeds in late summer or early fall, when they’re building reserves.

Try something different: Add a large hosta leaf to a fresh-cut flower bouquet.