Garden Flowers for the Dog Days

URBANA -- Summer is here and, before we know it, our gardens will be facing the hot days of August.

“Every year, we notice that certain plants are beautiful until the heat arrives, when they fade and wither,” said Martha Smith, University of Illinois Extension horticulture educator. Watering can become a nightmare during periods of high heat or little or no rainfall. However, with proper all-summer planning, a garden can look its best all season long.

In recent years, there has been increasing interest in low-water usage gardening, known as xeriscaping.

"The term xeriscape often brings visions of parched desert landscapes,” said Smith. "A xeriscape can be colorful, attractive, and inviting while requiring far less water than traditional landscapes."

By following a few basic tips, it is possible to have a colorful garden that uses less water.

-       Group plants according to their water needs, with the thirstiest plants in the same area. Concentrate on that area when watering.

-       Build soil lips or soil basins around plants to direct water to plant roots. Depending on plant size, this basin should be 3 to 18 inches from the base of the plant.

-       Mulch the garden to retain soil moisture.

-       Keep the beds free of weeds; they take water away from the desirable plant material.

-       If the soil drains too quickly, add moisture-holding organic matter to it.

-       Pick the right plant for the right spot. Choose plants that thrive in hot, dry conditions.

There is no shortage of colorful 'dog day' plants.

Celosia or cockscomb (Celosia argentea var. plumosa or C. argentea var. cristata) has unusual feathery or brain-like flowers of bright red, yellow, orange, and pink. It is an annual, meaning it grows from seed every year. Depending on the variety, it can be anywhere from 6 inches to 4 feet tall. It is an excellent fresh-cut or dried flower.

Spider flower (Cleome hassleriana) can grow to 4 to 5 feet tall, and it grows well in full sun. The spider-like flowers are rose, violet, or white. Cleome is also an annual and will re-seed freely.

Gomphrena or globe amaranth (Gomphrena globosa) is an old-fashioned annual that is easy to grow. It blooms in a variety of bright colors, including purple, orange, red, rose, and pink, and is 1 to 2 feet tall. It can be dried by picking it once it is fully open and hanging it upside down. When dried, it holds its color well.

Madagascar periwinkle or annual vinca (Catharanthus roseus) is a plant that seems to thrive in hot areas. Its lush, dark-green foliage is somewhat glossy and forms a 2-foot tall mound. Annual vinca is available in white, pink, purple, and bicolors and is recommended for gardens with a difficult southern exposure. It is slow to start if spring temperatures are cool, and it does not tolerate wet areas.

Threadleaf coreopsis (Coreopsis verticillata) is a perennial that will reach a height of 18 to 24 inches. It has yellow, daisy-like flowers that last from late spring to late summer. It grows best in dry areas with full sun.

Orange coneflower (Rubdeckia fulgida) is the perennial form of black-eyed Susan and has yellow or orange daisy flowers.

Blanket flower (Gaillardia species) is a perennial available in a variety of hot colors from golden-yellow to mahogany-red. Height varies according to cultivars, with most growing in the 2-foot-height range. Blanket flower tolerates dry soil and temperatures of over 90 degrees F.

Showy stonecrop (Sedum spectabile) is an upright perennial sedum that continues to amaze gardeners with new cultivars and introductions. Since ‘Autumn Joy’ was introduced in the 1990s, many more are now available, offering colorful foliage and flowers. All grow between 18 to 24 inches tall. They offer late summer flowers and grow best in well-drained soil and full sun.

“All the above mentioned plants will survive the hot days of August with very little attention and care except an occasional pruning off of the old blossoms,” said Smith. “Try one or two next year and enjoy your garden all season long.”