How to Keep Your Perennials Healthy Through Every Season

Perennials are an essential addition to any garden—after all, what's not to love about a low-maintenance plant that blooms year after year? Though perennials are typically easy to care for, they do require maintenance throughout the year to ensure healthier plants (and therefore more blooms).

We asked experts for tips on how to care for our perennials each season—from when to mulch and prune to the best time to divide and transplant. Keep in mind, though, that these are general tips. Not all perennials need the same treatment; when in doubt, look for specific care for the species in question.

Spring

Complete these tasks in the spring to give your perennials a good start to the growing season.

Prune

In very late winter or very early spring, prune branches of summer flowering vines, such as trumpet vine or wisteria, or flowering deciduous bushes, like rose of Sharon or viburnum, before branches start to bud. Trim them back to the length you need to encourage more growth during the season and to get rid of dead or damaged limbs. For vines, in particular, cuts in late winter encourage branching in the directions you want the vine to grow. Before disposing of your branches via trash bags, consider leaving them on the ground to allow for beneficial insects to come out of dormancy, and further bolster your garden.

"Quite a few native plants allow insects to live in hollow stems during the winter," says David Hillcock, consumer horticulturist and state coordinator of the Oklahoma Extension Master Gardener Volunteer Program. "Just leave the stems on the ground to allow the beneficial insects to finish their lifecycles." The exception to this is if you’ve trimmed a branch that looks like it might be diseased—then it’s best to remove it.

Clean Up Garden Beds

"Early spring is the time to clean up garden beds by removing debris, dead foliage, and overwintering pests," says Alex Betz, landscape designer at Plant by Number. Remove dead leaves, dead plants, and pull back decomposing mulch to allow plants to emerge from the soil. You can put any refuse in your compost bin, if you have one, as long as the plant matter you cleared looks healthy.

Divide and Transplant

Some perennials tend to multiply quickly if they were happy the previous year—but that may mean you now have a crowded garden. "For summer and fall blooming plants, spring is the best time to divide them up and move them," says Hillcock. Dig up any fall-blooming plants and bulbs, like anemones, coneflowers, and dahlias, and carefully divide the plants before transplanting.

Fertilize and Water

Most perennials don’t require a lot of soil nutrients, says Hillcock. "Native plants especially don’t need a ton of fertilizer. We encourage people to do soil tests and base their fertilization applications on those soil tests," he says. If you do choose to fertilize, apply a balanced fertilizer or compost around perennials as they begin active growth to encourage healthy flowering, says Betz.

Depending on where you live, if you’ve had a particularly dry winter, it may be good to water your garden to make sure plants have enough moisture to get started.

Summer

Now that your plants have been prepped in the spring, maintain them with these tasks during the summer.

Control Pests

If you’ve had your perennial plants for a few years, you may already know who’s eating your stems, leaves, and even roots, but it’s always good to keep watch, especially as temperatures warm and bugs emerge to eat. Be wary of pests you can’t easily see, like iris borer caterpillars that will tunnel through the leaves of the plant and eat through the rhizome. "There are some plants the pests like," says Hillcock. "You need to be prepared to treat accordingly."

Remove Spent Blooms

For some plants, you can extend your plant’s bloom period by removing spent blooms. Hollyhocks, geraniums, roses, and some varieties of hydrangea will rebloom if you’re quick to cut off the dead matter. "Enjoy your blooms longer by removing the flowers if they begin to fade," says Hillcock. "Do some tidying up and removing blossoms to encourage others to develop." Trim spent blooms and put them into your compost for more worm fodder. 

Prune

Some perennials grow exuberantly with water and sun and start to take over your yard (anyone who has grown forsythia can relate). "Summer is a good time for light trimming to control growth and maintain shape," says Betz. "Avoid heavy pruning, though, which can stimulate new growth that will be vulnerable to frost damage."

Weed

Sun and water not only encourage growth from the plants you love, but it also encourages plants you dislike to flourish. "Regularly weed garden beds to reduce competition for nutrients and water," says Betz. Unlike other removed plant debris, it may be best to toss weeds in the trash instead of composting them in case they’ve gone to seed. Otherwise, you’ll just be sowing weed seeds across your yard when you go to use composted dirt. 

Water

"Watering is one of the more difficult tasks in summer, and one in which you must be diligent to keep your plants happy," says Hillcock. Make sure to regularly inspect your plants for wilting and remember to water only when the sun is low in the sky during the evening or early morning to avoid water evaporation, otherwise your plants may not get enough moisture. 

Fall

Fall is when your perennials may be going dormant for the season. Set them up for success with these fall garden tasks.

Rake Dead Leaves

In the fall, rake your leaves into your garden bed instead of tossing them. "The leaves are habitat for beneficial insects and need them to hibernate," says Hillcock. "You can chop the leaves up first and scatter them up over the garden space for extra organic matter." You only need a few inches of leaf matter at most; the rest of your dead leaves can go into a compost bin.

Avoid Pruning

Even though the leaves are dropping and the plants are going dormant, don’t be too eager to cut back your perennials; too much pruning late in fall may stimulate new growth that’s likely to die off during a frost. "The only time we recommend removing plants is if the plant is harboring disease or pests. Then just cut the plant back and remove that material out of the garden," says Hillcock. It may be nice to leave some perennials as is for the winter to provide interest, such as grasses or coneflowers. Coneflowers, in particular, are great for grazing birds in winter, as the seeds from these flowers provide extra food.

Mulch

You should be prepared to mulch in the fall, but try to do so after the first frost. "You want the plant to go dormant first, then mulch the crown of the plant from the severe cold," says Hillcock. "If you try to mulch it too early, the foliage and the stems won’t harden off, and then you can get rot."

For larger plants, Betz recommends burlap wraps, or other protective covers to shield them from freezing temperatures.

Plant Bulbs

Fall is also a great time to plant bulbs for spring flowering plants, and you should aim to plant them before the first frost. "To protect the bulbs from critters, I recommend putting down some metal mesh over the planting area or another deterrent so the bulbs do not disappear before spring," says Betz. "But you should remove the mesh in early spring so the bulbs can flower."

Winter

Even if it's cold and your perennials aren't blooming, there is still some winter care to do.

Water

Though it may seem counterintuitive to water your garden when it’s cold outside, it can be beneficial, especially if you haven’t had any rain or snow for weeks and your soil is dry. "We encourage people to get out and irrigate their landscapes during warmer winter days if you have a chance," says Hillcock. "Dry soil is colder, and if it’s too dry, it can cause cold damage." Hillock recommends digging down several inches to see if the ground has any moisture before watering your garden. Pay attention to the weather forecast, and don’t do this if you’re about to experience a deep freeze.

Mulch

Mulch is a never-ending task, even if you put mulch down through all the seasons. "Monitor mulch depth to ensure it hasn't been displaced by wind or frost heaving, and top up if necessary," says Betz. At this point, mulch will help retain any moisture under the soil so the ground won’t get too cold, and it will help protect your plants from frozen soil.

Plan

And it begins again! Winter is a great time to think about where your new bulb or plant divisions will go in the spring, and to think about new plantings you’d like to make the following year. "Use winter to plan and prepare for spring, including ordering seeds or planning garden renovations," says Betz.