How to Maintain Perennial Beds and Borders

In the perennial garden, implementing effective maintenance practices such as mulching, proper watering, and timely deadheading can allow for healthy plants and beautiful gardens.

Below are the tasks that should be done throughout the year for perennials, including the best mulching materials, watering guidelines, and tips for fertilization and division. By following these practices, gardeners can ensure their perennials thrive and bring beauty to their landscapes for years to come.

Mulching

Mulches are an excellent way to reduce maintenance chores in perennial plantings. Mulches conserve soil moisture, reducing the need to water. Mulches also help control weeds by preventing the germination of annual and perennial weed seeds. Additionally, mulches prevent the splattering of soil onto foliage and flowers. This keeps the plants cleaner and may reduce disease problems.

Excellent mulching materials for perennial beds and borders are shredded bark and wood chips. These materials are widely available, attractive, and long-lasting. Other possible mulches include ground corncobs, shredded leaves, dry grass clippings, and pine needles.

Place 2 to 3 inches of mulch around the perennials. However, do not place the material directly over the plant crowns.

Learn more in this article: Using Mulch in the Garden.

Watering

Many perennials perform best when they receive 1 to 1 1/2 inches of water per week, either from rain or irrigation.

When watering, soak the soil to a depth of 8 to 10 inches. Watering frequency is largely determined by soil characteristics, weather conditions, and plant species. A thorough soaking once a week by Mother Nature or the gardener is adequate for most perennials.

Perennials, such as sedum, coreopsis, blazing star, and most ornamental grasses, possess excellent drought tolerance. Once established, these drought tolerant perennials require little or no watering.

Learn more in this article: Watering Tips for the Garden, Lawn, and Landscape.

Weeding

weeds with perennials — Regular weeding is an important maintenance task in the perennial garden.

Every perennial garden has weeds and dealing with these unwanted plants is an ongoing task in any landscape. Control of weeds is important. Weeds are strong competitors for available water, nutrients, and sunlight. Reduced air circulation created by tall weeds encourages the development and spread of foliage diseases and a weedy garden often has more insect problems. A completely weed-free garden is not a realistic expectation, but anything that can be done to reduce weeds is beneficial.

Weed management requires persistence throughout the entire growing season removing weeds when they appear and preventing them from getting large, flowering, or setting seed.

In the perennial border hand pulling, mulching, and careful applications of herbicides are often used. Learn more about all of the techniques you can use to maintain a (nearly) weed-free perennial garden in this article: Managing Weeds in Landscapes, Gardens, and Lawns

Deadheading

The removal of spent or faded flowers (deadheading) can prolong the bloom period for some perennials. It also improves the appearance of many perennials as the spent flowers are often unattractive. In addition, deadheading prevents fruit formation. Fruit development diverts a large amount of the plant s energy. This diversion of the plant's resources may weaken the plant, resulting in fewer flowers the following year.

Learn more in this article: Deadheading Herbaceous Ornamentals and Roses

Pinching and Cutting Back

Some perennials benefit from pinching early in the growing season. By removing the top inch or so of the stems, it forces plants to branch making them bushier and less likely to flop. Pinching is beneficial for chrysanthemums, asters, bee balm, garden phlox, veronica, Russian sage, and others.

Cutting back some perennials after flowering not only helps remove the spent flowers but can also promote new growth that will bloom again in several weeks. Cutting back works well to get a second bloom out of many spring-blooming perennials like salvia, catmint, perennial geranium, and spiderwort, among others.

Staking

Some perennials need support to prevent them from flopping on their neighbors, opening in the center, or snapping from wind or heavy flowers. Properly staked perennials are neater in appearance, but do not reveal the equipment used. Rings and cages can be placed around emerging perennials so they can grow through and be supported. A gridwork of bamboo stakes, sticks, or metal fencing can be used much in the same way. Tall stems can be individually attached to stakes to provide the needed support especially for cut flowers or tall stems that may easily snap in windy conditions. Proper placement also helps some perennials stand better. Too much shade and over fertilization can cause lanky growth that flops easily.

In nearly all cases, the best time to install staking materials in the perennial garden is early in the season so plants can grow up through and around the supports disguising them and improving appearance.

Learn more in this article: Staking Perennials.

Fertilizing

For most perennials, an application of 1 to 2 pounds of an all-purpose garden fertilizer, such as a 10-10-10, per 100 square feet is adequate. Excess fertilization produces weak, leggy growth and inhibits flowering. Early spring (late March to mid-April) is the best time to fertilize perennials in Iowa.

Learn more in this article: Fertilizing in the Home Garden.

dividing a hosta — Many perennials are best divided in the spring as the new growth emerges

Division

Many perennials need to be divided periodically to control size, retain vigor, or promote flowering. Division is also an excellent way to propagate a prized perennial. The best time to divide perennials varies with the different plant species. Specific times can be found in this article: How to Divide and Transplant Perennials.

Expanding Perennial Beds

As plants grow and new species are introduced, the perennial border or bed may need to grow in size to accommodate all the plants. The first step to expanding (or creating) a perennial garden bed is to remove the existing sod. There are several methods you can take to remove the turfgrass, and each has its advantages and limitations. Smothering, heavy mulching, digging, tilling, and herbicides are all options. Which method you choose depends on the time it takes, the amount of work required, and your personal preferences. Thorough removal of the turf and other weeds is essential to minimizing issues with weeds in the future.

Learn more in this article: How to Kill Grass to Create a New Garden Bed.

Planting

There is always a new perennial to be introduced to the border. As the garden grows and develops conditions change and plants need to be moved or replaced. Proper planting and care after planting is essential. Learn more in this article: How to Plant Perennials.

Cleanup

After the first frost in the fall, we are sometimes compelled to cleanup the dead plant debris. While perennial plants can be cut back in fall after the foliage has been destroyed by a hard freeze, it is beneficial in many cases to wait until spring.

Leaving the leaves, stems, dried flowers, and seed heads of many perennials provides more interest through the winter months. Leaving the plant materials also provides an extra layer of protection for the crown and root system of the perennial. Plus, the dead stems and leaves collect fallen leaves adding even more protection. Leaving the plant material in place and removing it in early spring instead of fall also helps provide food and protection to native pollinators, beneficial insects, and wildlife, like birds.

While it is largely beneficial to leave foliage in place through winter, removal of plant material in the fall after it has naturally died back should be done for those perennials that had disease or insect pest issues during the summer. Additionally, those perennials that tend to be weedy or spread aggressively by seed benefit from late season deadheading and clean up to prevent them from being too weedy.

Overwintering

Some plants in the perennial border need a little extra protection to make it through the winter months. When you take a few extra steps to protect these plants, it can greatly reduce maintenance tasks during the next growing season.

Frost Heaving

Leaving plant debris in place over the winter months can help those shallow rooted perennials that may frost heave. Frost heaving happens when the freeze-thaw cycle of the upper layer of soil works the crown and root system of the perennial plant out of the ground. If more protection is needed to prevent frost heaving, apply about four inches of mulch over the crown of the plant after the ground freezes, typically by late November in much of Iowa. Do not place the mulch on too early as it can slow plants from going dormant and make them more susceptible to damage from cold temperatures. Remove the excess mulch “blanket” in early spring as soon as the top layer thaws, typically around mid-March in much of Iowa.

Mulching Tender Perennials

Tender perennials and perennials planted in late summer/early fall should also be mulched to prevent injury. These plants can also be protected with cages placed around the plants and filled with straw, pine needles, or chopped corn stalks. As with extra mulch, place the protective layer late in the fall season and remove it in early spring. A 6- to 8-inch-layer should be adequate for most perennials. Do not use Styrofoam cones or domes as they can cause premature warming in the early spring bringing plants out of dormancy early and making them more susceptible to cold damage. Additionally, most plants will not fit under these cones without extensive pruning and it is better to prune in spring rather than fall.

Learn more in this article: How to Overwinter Plants.

More Information

Authors:

Aaron Steil

Richard Jauron

Last reviewed:

July 2024