University of Illinois Extension


Sharon Yiesla
Unit Educator, Horticulture
Lake Unit

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Late Summer Perennial Gardening Tips

Sometimes when we get to the end of a long hot summer, it seems like there is nothing to do but give up. By August, the garden can look tired and tattered. There are some things that can be done now to revive the garden.

Now is a good time to look around and see where the ‘blank’ spots are in the garden; to see what part of the garden is lacking bloom. We often see these blank spots, because all the plants we bought in spring were spring or early summer bloomers. Now we can go to the local garden center and pick some plants that will give us bloom in late summer and early autumn. Planting at this time will require some extra care since temperatures may be high and rainfall may be low. New plants will need regular watering so that they establish well.

Looking at the garden we already have established, there are some things we can do to keep it in good shape. Watering should be our number one concern. It is essential to keep plants watered consistently during the heat of summer. On average, plants need about one inch of water per week and it is best to give it that whole inch at one time. A good deep watering once a week helps the plant develop a deep root system and gives the plant a good reservoir of water from which to draw. Avoid frequent sprinkling as it never wets the soil thoroughly. During really hot weather we may need to make that inch of water available every five days instead of every week. The weather and the plant’s environment will dictate water needs. Keeping plants watered helps keep them growing well and looking good.

Mulch can play an important role in the garden at this time. Mulch helps conserve water, keeps root systems cooler and reduces weed problems. During this time of year, inspect your mulch to see if it is still intact or if it has decayed down to a thin layer. A 2-3 inch layer of mulch is a good amount. Less than that may be insufficient to get the job done. If your mulch layer is depleted, go ahead and add some.

The question of fertilizer always comes up in any discussion of gardening. The question to ask now is “Do my plants need fertilizer now?” Late summer is not always a good time for fertilizer. Plants are often under heat or drought stress and fertilizer will not help them. In some cases it may even be harmful. Plants that are in dry soil may have their roots burned by fertilizer, even when the correct amount is used. If a plant is dry give it what it needs—water and save the fertilizer for another time.

Some plants may need to be rejuvenated in late summer. If some of your perennials have turned brown or become tattered, cut them back and then give them some water to encourage new growth. Many perennials respond favorably to this kind of treatment and if one or two don’t, then at least you have removed an eyesore from the garden. Those plants that don’t regrow now, will do so next spring from the root system.

Deadheading can also improve the look of the late summer garden. Remove spent flowers to keep the garden tidy. You may not want to deadhead everything, especially if you are trying to get plants to naturalize or if you are trying to attract birds. Know what your purpose is and then deadhead select plants.

A final task, and the one many gardeners dread, is weeding. Sometimes our late season gardens look bad because the weeds have gained a foothold. Get out and get the weeds out and the garden will begin to look better immediately. Also your perennials will grow better without the competition of the weeds.

Don’t let late summer take it’s toll on your garden. With a few simple steps, we can keep the garden beautiful and productive throughout the entire season.

August - September 2003: Cytospora Canker of Spruce | Living with Snakes | Late Summer Perennial Gardening Tips | Dealing with White Grubs in Lawns | Pine Wilt

Past Issues

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