URBANA, Ill. – Planning a perennial garden can be challenging when faced with weather extremes. The Midwest can often be hot and dry throughout August. Drought-proven perennials can provide relief to a stressed summer flower garden. 

Silver foliage plants that thrive in full sun also tolerate drought conditions, says Martha Smith, University of Illinois Extension horticulture educator. "Roots of gray foliaged plants will often rot in wet soil, and the foliage tends to decline in high humidity climates."

Artemisia cultivars such as "Powis Castle," "Silver King," and "Silver Mound" all tolerate rock garden conditions. Echinops ritro (Globe Thistle) performs well under hot, dry conditions. Stachys (Lamb’s Ear), Perovskia (Russian Sage), Achillea (Yarrow) and Santolina (Lavender Cotton) cultivars all prefer well drained, hot planting sites.

Hemerocallis (Daylily) cultivars withstand hot and dry conditions. These adaptable plants are available in a wide range of flower colors and sizes. "Be sure to choose early-, mid- and late-blooming cultivars to extend your season of visual interest," Smith says.

Coreopsis and Gaillardia cultivars are two other considerations for the dry, sunny garden. Coreopsis offers flowers in shades of gold, and Gaillardia contributes orange and burgundy flowers. Both of these species will provide color most of the summer.

Callirhoe involucrata (Poppy Mallow) requires very little moisture due to a long taproot. This low growing, sprawling perennials offers reddish-purple blooms all summer.

"Many of the ornamental grasses do very well with little water," Smith says. "Miscanthus, Saccharum (Northern Pampas Grass) and Panicum (Switch Grass) cultivars are all warm season grasses that love the heat."

Cool season grasses, such as Helictotrichon sempervirens (Blue Oat Grass) shine in the hot summer garden. Calamagrostis (Karl Foerster) also gives a good show in July and August. Many of the ornamental fescues rot in heavy, moist soils and thrive in drier locations.

"There are many perennials you can incorporate into your garden that will survive extreme summertime growing conditions," Smith says. "Realize that pre-plant soil preparation also aids their survival as does a 2 to 3 inch layer of organic mulch."

SOURCE: Martha Smith, Horticulture Educator, Illinois Extension
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