August Calendar Photo Credit Debra Othitis.jpg

August is a good time to audit your gardening efforts and make notes for next year about what worked and what didn’t.

This is a good time to audit your gardening efforts and make notes for next year about what worked and what didn’t. Were you happy with that new tomato variety? Did that perennial get enough hours of sun or should it be moved? Meanwhile, here are some late summer tasks to undertake.


• Harvest beans, tomatoes, cucumbers, summer squash and corn often so they continue to produce. Use clean scissors or small shears to harvest instead of pulling on plants or stems.

• At midmonth, direct seed fall season crops like spinach, radishes, Swiss chard and beets.

• Onions are ready to harvest when their green tops fall over. Lift the bulbs, brush off loose soil, and lay them out in a single layer in a protected are on a surface that permits ventilation top and bottom.

• Peppers can be harvested anytime they achieve the size you need or want.

• Bigger eggplants aren’t better, so harvest when they are large enough to use, but before the skin loses its gloss.

• Water tomatoes regularly until late August. After that, fruit will ripen more quickly when water is withheld.

• Fertilize tomatoes when the fruits are one-third grown, again after picking the first ripe fruit but not thereafter. Use a general vegetable fertilizer such as 5-8-4.

• When garden beds become empty after harvesting, sow cover crops, often called green manure, like annual rye grass or buckwheat to build garden soil.

Perennial flowers

• Continue deadheading to extend the bloom season.

• Mid-August should be the last feeding time for roses. If they are repeat bloomers, this will help with their final flush of blooms. Fertilizing later may stimulate new succulent growth that could damage the plant if there is an early frost.

• Divide spring and early summer blooming perennials as necessary.

• Order fall bulbs, including garlic and onion planting stock.

Diseases and pests

• Powdery mildew is a fungal disease that can appear in your perennial and/or vegetable gardens as patches of white or gray powdery substance. It attacks where plants are crowded and kept damp. Susceptible plants are garden phlox, bee balm, Virginia creeper vine, roses, squash, pumpkins and cucumbers. To avoid the disease avoid overhead watering where these plants grow and space plants farther apart to encourage air circulation. Sulfur products sprayed during the growing season may help control powdery mildew.

• Yellow jackets can be a major headache at August picnics. These aggressive carnivorous insects are attracted to your picnic plate. Pheromone traps may provide some relief.


• Starting midmonth and continuing through fall, begin lawn renovation and repair. Build up low areas with garden soil and over-seed areas that are thin or bare.

Shrubs and trees

• Newly planted trees and shrubs need consistent watering to get established.

• As woody plants move into their dormant period, it is best not to fertilize or prune except to remove any broken or damaged branches

The El Paso County Extension is operating remotely due to COVID-19. Submit gardening questions by email at

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