This Is The Best Time To Switch Out Summer Perennials—And How To Do It

I may be summer-blooming perennials' number one fan. I love a plant that, when given the right type of care, fills my garden without having to be propagated, purchased, or planted every year. Oh, I'll give annuals some space each summer, but my flowering and foliage-forward perennials are the stars of the show.

I have a gardening friend who is ruthless with plants when they fail to perform to his expectations. Out with the old and in with the new. I tend to nurture old favorites, but if you are tired of the same old perennials, late summer is the time to refresh the garden or divide some perennials for a new look.

Understanding Perennials and Their Growth Cycle

A perennial is defined as a plant that will live for more than two growing seasons. While some perennials can be short-lived and last only a few years, others may last for decades. Many summer-blooming perennials are true herbaceous perennials. The plants die back in the fall or early winter while the roots remain viable. Every spring, they send out new shoots from the ground.

Some common summer perennials are black-eyed Susans, coneflowers, bee balm, daylilies, blanket flowers, daisies, hostas, and yarrow.

When to Switch Out Summer Perennials

If you are a ruthless gardener and ready to get rid of a summer-blooming perennial, you can do it anytime. Ideally, if you plan to transplant the specimen or divide the plant, wait until late summer or early fall when temperatures have cooled a bit. By that time, the majority of the perennial's growth cycle is over, and it is beginning to go into dormancy.

Preparing for the Switch

Before you grab your garden spade, step back and take a good look at your garden beds. Has a perennial overgrown its space? Is the plant not performing well due to improper light or water requirements? Have you accidentally planted one yellow daylily in a bed of deep red lilies? Do you have areas that you want to fill in with or switch to annuals?

Once you have answered all of the questions, it's time to take a soil sample to assess the condition of your garden soil before making changes. Most perennials prefer soil that is well drained with good fertility and a pH of 6.0 to 7.0. The results of your soil sample will tell you what amendments need to be made, but you can never go wrong by adding organic matter to improve fertility, texture, and water-holding capacity.

How to Remove Summer Perennials

If you are ready for a fresh start and your current perennials are healthy, find them a home with a friend or offer them up to other gardeners who will be delighted to have them.

1. To safely remove the plants without damaging surrounding plants, use a sharp garden spade and dig straight down several inches out from the outermost stems.

2. Lift the plant from the soil with the root ball or system intact.

3. Place the plant in a plastic pot or wrap the root ball with newspaper for transport.

4. Refill the hole with good garden soil or the new plant you've selected.

5. To divide a perennial clump, use an old, large knife, and cut the clump into sections, making sure to leave a main stem in each division.

Selecting New Perennials for Planting

Before planting new perennials, consider the conditions of the planting site, including your USDA hardiness zone, light exposure, soil type, slope, drainage, and air circulation. For gardening success, you need to know the needs of the perennial (light, soil, water) and the size of the plant when it reaches maturity.

If you are selecting summer-blooming perennials for next year, consider these:

• Bleeding Heart (Lamprocapnos spectabilis): Perfect for deep shade gardens in zones 3a-9b.

• Astilbe (Astilbe japonica): Produces a pop of pink in full to partial shade gardens in zones 4a-9b.

• Ice Plant (Delosperma cooperi): Perfect for dry, rocky soils, give this perennial full sun in zones 6a-10b for flowers all summer long.

• Sneezeweed (Helenium autumnale): Tolerant of most soils, this fall-blooming perennial enjoys full sun to partial shade in zones 3-8.

• Ageratum (Conoclinium coelestinum): A late summer bloomer, it enjoys slightly acidic, moist soil and full sun in zones 5-10.

• Shasta Daisy (Leucanthemum × superbum): A hardy perennial that blooms throughout the summer until the first frost in zones 4a-9b.

• Coreposis (Coreopsis verticillata): Perhaps the longest blooming summer perennial, this plant tolerates all types of soil in full sun in zones 3a-9b.

Planting New Perennials

1. Amend the soil following the guidance of your soil test. Work amendments into the soil evenly to a depth of 8 to 10 inches so the soil is loose and easy to work.

2. Dig a hole that is as deep and twice as wide as the root ball or pot containing the new perennial.

3. If the perennial is pot-bound, loosen the roots around the bottom and sides of the root ball and spread them out in the bottom of the planting hole.

4. The crown of the plant, or where the roots and green growth join, should be even with the soil surface.

5. Refill the hole, firming the soil around the plant to avoid air pockets.

6. Water the new perennial thoroughly following planting to settle the soil around the roots.

Caring for Newly Planted Perennials

New plants in the garden require plenty of water, usually 1 to 2 inches per week from rain or irrigation. Water thoroughly and deeply, but allow the soil surface to dry before watering again. Using drip irrigation or soaker hoses is ideal because the water is applied slowly and the foliage remains dry, helping to prevent foliar disease.

Mulch new or transplanted perennials with a 1- to 2-inch layer of compost, pine bark, or pine straw to help conserve moisture. Leave a 1 to 2 inch gap between the crown of the plant and the mulch to help prevent crown rot.

Since you are planting perennials in late summer, do not add additional fertilizer that can result in excessive growth that can be damaged by an early frost. Wait until spring to add fertilizer for a jump start on summer growth.

When temperatures drop and the first freeze happens, cut back dead stems and foliage above the mulch layer for a neat appearance in the winter garden.

Read the original article on Southern Living