Perennials are the come-back stars of the garden. In contrast to annuals, which die off at the first frost and need to be replanted every year, perennials return each spring after going dormant in winter. Healthy, happy perennials, like long-blooming coneflower and shade-loving hosta, will vigorously grow and multiply, creating a vibrant garden teeming with life. As easy care as a perennial garden can be, a few common mistakes hinder perennials from thriving. Whether your plants aren't producing as many flowers or growth is stagnant, a common perennial garden mistake is likely at play—but there are ways to fix each affliction to nurture a lush, colorful landscape.
Ignoring Your Zone
Every perennial has a hardiness zone range based on the lowest average temperatures in each region. The spectrum runs from Zone 1, which experiences the coldest average temperatures, to Zone 13, which experiences the hottest. If you live in Iowa, which falls in Zones 4-5, a tropical plant that prefers conditions in Zones 8 or higher is unlikely to be compatible with your landscape. Choose plants that thrive in your zone to maximize the success of your perennial garden.
Putting Perennials in the Wrong Spot
PETER KRUMHARDT
The old garden adage "right plant, right place" refers to matching a plant's light requirements and soil preferences to a spot in your garden that meets its needs. Knowing the preferred growing conditions of your perennial garden plants is as simple as checking the information tag when you're at the nursery or consulting a plant encyclopedia. Consider the type of light your yard gets before plant shopping so you know which perennials will jive with your garden, and provide soil amendments as needed to help your chosen perennials thrive.
Not Planting for Color Through the Seasons
THE SPRUCE / EVGENIYA VLASOVA
If you strategically choose plants when planning your perennial garden, your landscape will bloom from spring through fall. Most perennial plants bloom for about three weeks. To stagger blooming in your landscape, choose perennials that flower at various times of the year. Early-blooming species like hellebore and trillium will show during spring, and late-season perennials such as aster, black-eyed Susan, and Russian sage will take over in summer through fall.
Pair flowering perennials with perennials prized for their foliage, such as hosta and sedum. Their leafy color and texture add dimension to the garden while complementing plants with more showy flowers.
Planting Too Close
MATTHEW BENSON
A young perennial in a 4-inch pot can easily expand to cover several feet over a few years, so when adding new plants to your perennial garden, account for the width and height they're expected to reach once fully grown. Choose sites based on the plant's mature size, considering nearby plants, structures, and pathways. This will also help prevent illness in your plants, as crowded perennials create conditions that encourage disease. Perennials grow slowly in the first year, but in the second year, you'll notice a rapid increase in growth, and by the third year, they usually reach their full size.
Mulching Too Much or Too Little
A 3-inch layer of organic mulch, such as shredded bark, will help keep down weeds and retain moisture in the soil of your perennial garden. Avoid mulching 2-3 inches from the crown of each plant, as mulching too close to or over the crown can slowly suffocate the plant or allow diseases to take hold. Mulch breaks down over time, so spread a fresh layer annually.
A thick 6- to 8-inch layer of mulch helps insulate fall-planted perennials from harsh winter conditions. If you apply a mulch blanket to newly planted perennials in late fall, remove it in early spring so the soil can quickly warm up as air temperatures rise.
Not Staking Tall Stems
Some perennials need a little help to stand tall. Delphinium, peonies, and aster are just a few plants with long or thin flower stems that tend to flop onto the ground when they bloom. Prevent this by staking the stems before the plant's flowers bloom. You can use single stakes or a grow-through grid, depending on what works best for the plant you need to support. Or, if staking is a chore you would rather avoid, look for more compact varieties of your favorite perennials that won't require support.
Neglecting Maintenance
KATIE BURDETT / BHG
While perennial plants are generally low-maintenance, they look even better when you give them a little extra TLC. Regular deadheading encourages plants to channel available energy into developing a healthy root system and, in some cases, another flush of flowers later in the season. Division also helps reinvigorate many perennials—aim to divide plants in your perennial garden every three years or so.