By Alex Tisthammer | Fort Collins Nursery
As August heat settles in, many plants in our yards start to bear a resemblance to ourselves – hot, unmotivated, and craving cooler temperatures. Certain plants like peonies (Paeonia ssp.), bleeding hearts (Lamprocapnos spectabilis), and Virginia Bluebells (Mertensia virginica) recoil into the cooler soil and go dormant. Others, like salvias and ‘Snowdrop’ Anemone, take a break during the hottest months and rebloom once it cools down. Fortunately, when the spring bloomers throw in the towel, a handful of sun and shade plants step up and keep beds looking gloriously lush in the heat of summer.
A well-loved perennial that takes the spotlight in August is the hardy hibiscus. Despite looking tropical, hibiscus performs quite well in Colorado, tolerating clay soils and thriving in moist conditions. The large, dinner plate-sized blooms unfurl to colors of pink, red, white, or lavender. Even though they regrow from their root system every year, hibiscus get quite large (up to 5 feet) quickly once the weather warms up. Rudbeckia, another wonderful sunny perennial, appears to mirror the sun above with its large, yellow ray flowers. The longevity of their flowering season and their habit of reseeding make them a must, even though some varieties are short-lived. A whimsical native often enjoyed by bees and butterflies along bike paths this time of year is Dalea purpurea, or Purple Prairie Clover. This sun-lover creates an attractive bush of delicate leaves while rose-purple flower cones waft above. Their extensive root system makes them drought-tolerant, and they are nitrogen fixers for the soil.
Sun lovers don’t get all the glory in August. There are also shade plants that stand up to the heat and look beautiful in late summer. Culver’s Root (Veronicastrum virginicum) is tall, elegant, and unique. It is a lesser-known perennial that has towering stems of whorled leaves and spikes of pink, white, or lavender flowers that resemble veronica. Native to moist prairies and open meadows, it does best in light shade and moist conditions. Chocolate Snakeroot (Ageratina altissima ‘Chocolate’) is another shade lover with a distinctive appearance. Aptly named, it has deep purple-brown foliage that adds a wonderful sense of moodiness to the garden. Delicate clusters of white puffs will appear on top of the dark foliage in August. Most think of violas as only an annual, but there is an ever-growing selection of perennial violas that bloom their hearts out from late spring until frost. Some, like ‘Etain’, even have a fragrance. They continue blooming throughout the season without any maintenance, but are infinitely more attractive if cut back after their first round of blooms and given a light, balanced fertilizer. Without this, they tend to sprawl and lose their mounded shape. Doing this in July will encourage another big push of flowers in August.
Planting perennials that relish the heat and sun will revive you and your garden until the cooler nights arrive. When your other plants have given up or are taking a break, they will rally through the heat!