Don’t Sweat It: August Gardening Tips

July 25, 2022

The “dog days of summer” seem to reach a peak in August when interest wanes in mowing lawns, weeding flower beds and gardens, and watering potted plants. But just as all seasons seem to pass quickly, this one will too. By the end of August, having a few cool nights will remind us that the summer season will soon pass. In the meantime, here are some suggestions of what you might be doing in your garden during this month.

Watch for the foliage of your early blooming plants, such as iris or bleeding heart, to start turning yellow. When it does, it is time to lift and divide your plants. For iris, divide the rhizomes and cut back the leaves to about six inches in a fan shape. Cut out any of the borers or rotted rhizomes. The healthy rhizomes can be replanted at the soil level or just slightly below. Plant them back-to-back with the growing points facing outward about five inches apart. Any rhizomes that you don’t want can be given away or swapped at a fall Master Gardener Plant Swap.

Bleeding hearts don’t require dividing any more than every five years and division can be done in the early spring or the fall. Dig a wide circle around the crown of the plant to get as many of the roots as possible. Using a sharp knife, divide the plant, keeping several of the pink buds (new growth) in each division. Dig a wide hole and plant the newly divided plants no closer than two feet apart. Add some compost to the hole, cover with about an inch of soil and water well.

Some gardeners ask about dividing peonies; however, these plants seldom require division because they are quite long-lived. Some reasons you might want to divide or move peonies are the need for more plants, they are producing fewer blooms, or they are having frequent disease problems. Peonies can be divided or moved in September or early October.

Start collecting seeds from some of your perennials as soon as they ripen and sow them. Sow them in a location where they won’t be mistaken for weeds and pulled out. Consider labeling the rows or writing down what you have planted in a gardener’s journal. These perennials might include columbine, delphinium, bee balm and heuchera seeds. Some of these seeds might germinate right away and others will require cold weather and germinate in the spring.

Continue watering your perennial plants in August if it is dry and hot, but don’t fertilize them this late in the season.

August may prove to be the worst month for insects because by this time of the year, they have increased in size and number. However, minimize controlling insects with chemicals as a last resort. Chemicals potentially kill beneficial insects, in addition to those you are trying to get rid of. Many destructive insects, such as Japanese beetles, can be hand-picked off the plants and placed in a pail of soapy water.

Watch for mildew on your plant leaves. Cool nights with dew contribute toward this disease and you may have to use a fungicide to protect your plants. However, since it is late in the growing season, you can also just ignore the problem. The fungicide may stop the mildew, but it won’t change the looks of the damaged leaves.

Keep weeding. Remember that the weeds are setting their seeds now that will germinate new weeds in the spring. Eliminate the weeds now and you’ll cut back on an extensive garden clean-up next spring.

Keep harvesting. Pick squash, cucumbers, and tomatoes so that they don’t become over-mature and others so that they don’t go to seed or become inedible. Harvesting your produce also ensures that the plants will keep producing. Now is the time to share extra produce with your friends and neighbors.

Remember that August is not a good time to plant shrubs. It is usually too dry and hot for shrubs to get a good start. However, if you must plant in August, check your shrubs each day and give them plenty of water, taking care not to drown them.

Start a fall garden. There is still time to sow beans, beets, spinach, cabbage, broccoli, and turnips for fall. Some cold-tolerant plants will continue to produce even after the first freeze. Remember to water the garden early in the day if it does not rain for a week to 10 days and apply one inch of water to the garden.

Enjoy August because gardening chores increase during the fall months! If you have questions about gardening, please contact any Master Gardener or your local University of Illinois Extension office.

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