For gardeners who prefer low-maintenance gardening, that’s the ultimate goal: a showy display of flowers and foliage without the fuss of summer-long watering, weeding, pinching, pruning, and spraying. “Plant them and forget them.”
Low-maintenance perennial gardens may require you to slightly change your standards of formality or showiness. But, if you select the right perennials—those adapted to your climate and specific garden setting—and then follow a few low-maintenance strategies, you won’t need to be a slave to your gardens to enjoy fabulous season-long splendor.
To find the toughest perennial performers, for six consecutive years I conducted research on the performance of North American native perennials in low-maintenance landscapes at the University of Missouri’s Southwest Research Center in Mount Vernon, Missouri (Zone 6), and at the University of Illinois, Urbana-Champaign (Zone 5).
The criteria we developed for the study weeded out all but the top performers: After a year of establishment, the plants had to survive on their own. The only care they received was a late-winter cut back and an occasional weeding.
What puts a perennial in the low-maintenance category?
1: They must have no significant disease or pest problems.
2: You won’t need to divide them to keep them blooming profusely.
3: They’ll survive the climatic extremes of summer and winter in the garden.
4: Even when not in bloom, the plants’ foliage is attractive.
5: The flowers and foliage hold up well all season with minimal supplemental fertilization and watering.
6: Their stems are strong enough to hold up the entire season with no staking, pinching, or pruning.
7: The plants are not weedy: They don’t self-seed freely or require frequent division to keep them from overstepping their bounds.
20 perennial winners
Many perennials are spectacular for only a few weeks each year. In our research trials, season-long, attractive appearance was important. We tested more than 90 species of native plants, giving them an appearance rating from 1 (poor) to 4 (excellent) every two to three weeks during the growing season.
Only those that averaged at least 3.5 throughout the entire season are listed below. We also considered such plant characteristics as height, width, growth habit, flower effectiveness, flower coverage, color of blooms and foliage, attractiveness of seed pods, autumn color, and freedom from pest problems. Here are our top choices, in order of bloom time.
In late April, Texas blue star (Amsonia ciliata, Zones 5 to 9 graces the garden with steel-blue, star-shaped blooms on a 3-foot-tall plant. A close relative, Amsonia illustris, Zones 5 to 9, is larger, coarser, and blooms a couple of weeks later. Both have foliage that is attractive all season, especially when it turns gold in autumn.
New Jersey tea (Ceanothus americanus, Zones 4 to 8) is a shrub rather than an herbaceous perennial, but its 3- to 4-foot height mixes well with perennials in the border. Clusters of white blooms from late April into June are followed by red fruits that eventually turn black, creating an everchanging, attractive display.
Don’t let the common name of horsemint keep you away from Monarda russeliana, Zones 4 to 8. It shares none of the aggressive characteristics associated with mint-family thugs. It is also free of powdery mildew, the bane of its relatives, common garden bee balm. Horsemint blooms in May and early June, producing lavender flower clusters on compact 15-inch-tall plants. After blooming, it forms attractive rounded seed heads. Throughout the growing season, new foliage has a maroon cast, and in autumn the plant may develop this rich hue.
A pair of penstemons, prairie penstemon (Penstemon tubiflorus, Zones 5 to 8) and smooth penstemon (P. digitalis, Zones 2 to 8), send up 4-foot-tall spikes of white, bell-shaped flowers from late May through June. When done blooming, attractive mahogany seed pods form. Fall foliage for both often develops red tinges.
Purple prairie clover (Dalea pur-purea, Zones 4 to 11) makes a feathery, shrub-like plant with purple or white blossoms from early June to mid-July. Flowers remind me of little ballerinas with short fluffy skirts projecting from the central core.
One of the longest bloomers in the trial was dancing butterflies (Gaura lindheimeri, Zones 6 to 9). The common name refers to the pink and white bracts below the creamy white flowers, creating the appearance of delicate butterflies fluttering on 3- to 4-foot-tall stems. Blooms are present from early June into November.
Two outstanding bloomers are Tennessee coneflower (Echinacea tennesseensis, Zones 3 to 9) and yellow coneflower (E. paradoxa, Zones 5 to 9). Tennessee coneflower has deeply rose-pink blooms from mid-June into September on 2- to 3-foot-tall plants; yellow coneflower has yellow blooms in June and July on 3- to 5-foot-tall plants.
Lead plant (Amorpha canascens, Zones 2 to 6) derives its common name from feathery leaden-gray foliage, the plant’s most attractive feature throughout most of the year. From mid-June into early July, rich-purple blooms form at the tips of 4-foot-tall stems. Rabbits may graze the foliage early in the season, but results only in more compact plants that bloom slightly later in the season.
Make a striking architectural statement with rattlesnake master (Eryngium yuccifolium, Zones 4 to 8). Its leaves are sharply pointed, straplike, and blue-green, similar to yucca. By mid-June the plant stretches to 4 to 5 feet in height and forms 1-inch-diameter balls of greenish-white flowers that are attractive to butterflies. In fall and winter, interesting orb-like brown fruits develop.
Most ornamental onions flower in the spring. Nodding pink onion (Allium cernuum, Zones 4 to 10) is an exception. Yellow-green foliage is topped with umbels of delicate pink blooms in early July to August, beginning with a slight crook at the end of the stem, creating the “nodding” effect.
Virginia mountain mint (Pycnanthemum virginianum, Zones 4 to 8) is a noninvasive 3-foot-tall clump-former with gray-green scented foliage. From early July through August it bears white flowers with purple flecks. Gray seed clusters persist through the winter.
Prairie blazing star (Liatris pycnostachya, Zones 4 to 9) and small-headed blazing star (L. microcephala, Zones 4 to 8) develop spikes of lavender blooms in July and August on plants with attractive grass-like foliage. Blooms are attractive to butterflies and bees.
True-blue flowers from late August into October are the highlight of blue sage (Salvia azurea, Zones 7 to 9). Combined with the silvery-gray foliage, it makes a stunning late-season garden display. The blooms are a hit with migrating monarch butterflies. While the 5-foot-tall plant has a tendency to flop, it will remain upright if combined with other tall perennials.
Letterman ironweed (Vernonia lettermanii, Zones 5 to 8) has feathery-textured green leaves that retain their excellent color even through searing heat and drought. From late August into October, sprays of magenta-purple blooms adorn the tips of the 3-foot-tall stems. As nights get cooler, stems take on a purplish cast.
Gray goldenrod (Solidago nemoralis, Zones 4 to 8) and blue-stemmed goldenrod (S. caesia, Zones 4 to 8) round out the gardening season. Both form 3- to 4-foot-tall clumps and panicles of yellow blooms. Gray goldenrod begins blooming in late August and continues into October. Blue-stemmed goldenrod starts in mid-September. The common names derive from the gray-green foliage of the former and the bluish cast to the stems of the latter.
• Choose the right plant for the right place. Consider sun or shade tolerance, soil type, wind exposure, drainage, and temperature extremes. Native plants are a good starting point, but plants from other regions with similar climates are also a good bet.
• Eliminate perennial weeds. Spray planting beds with with a broad-spectrum herbicide, such as glyphosate (Roundup), at least 10 days before planting. For a non-chemical approach, cover the area with black plastic the season before planting to smother weeds.
• Till soil deeply. Many low-maintenance perennials survive on little water because their roots penetrate deeply, tapping moisture reserves in lower levels of the soil.
• Amend planting beds if necessary. Ideally, you’ll find plants adapted to the type of soil found in your yard. But if you’re “blessed” with heavy clay or pure sand, growth of most plants will benefit from addition of organic matter, such as compost or well-rotted manure. Caution: Some native plants put on excessive growth if the soil is too rich.
• Mulch, mulch, mulch. A 2- to 4-inch layer of your favorite organic mulch will keep weed competition to a minimum, preserve and trap soil moisture, prevent soil erosion, and moderate temperature extremes.
• Water appropriately. Even the best-adapted species will need some water to get them off to a good start. For the first growing season, water thoroughly but infrequently. Wet the full root-zone depth when watering, but allow the top inch or so of soil to dry out between waterings.