Tips for Growing Perennial Plants

Perennial flowers in a garden.

If you're growing perennial plants for your summer garden, you're investing in a gift that beautifully blooms year after year. Even better is knowing that as your plants grow and thrive, you can divide and expand your flower garden or choose to share plants with others.

Here's a look at tips for growing perennial plants and giving them a solid, healthy start in their new home.

Getting Started

To start your plants from seed, sow indoors with a seed starter tray according to packet directions (typically 10 to 12 weeks before your last frost date). Keep them in a warm location with soil that's moist but not soggy as seedlings emerge. Keep turning the tray for even sunlight through a window, or use grow lights to help them grow strong and straight. You'll need to harden off your seedlings in a protected spot outside to get them used to outdoor sunlight and breezes before planting them in your garden or pots.

If you don't want to start from seed, you can order garden-ready plants online. Perennial seedlings should be vigorous, with a well-developed root system. If you order online, be sure to unpack them as soon as possible and water them well. Place the seedlings in a protected area with morning sun, keep them watered and plant them within a few days.

Prepare the Garden Soil

Using a spade or garden fork, loosen and turn the soil where you intend to grow perennial plants. Break up clumps and remove any weeds and large rocks. Work in some coconut coir or compost to add nutrients and organic material that will help hold moisture. These additives also lighten soil that's dense and doesn't drain well.

To successfully grow perennials, you'll want soil light enough for roots to spread out but not so dense that roots get waterlogged and potentially rot.

Dig Holes and Plant Gently

Dig holes for each plant that are a little larger than the root ball. Set each plant with its crown (the part where the stems emerge just above the roots) even with or slightly below the level of the soil. Fill in around roots with fine soil and press lightly. Leave a slight depression or "saucer" around the plant to catch and hold water. Gently add about a quart of water to the "saucer" around each plant. Water again and let it let soak in.

Keep Your Plants Watered

Water your seedlings thoroughly at least once a week. A good soaking of about 1 inch of water a week encourages roots to grow deep. With shorter, more frequent waterings, the roots tend to stay closer to the surface. Deep roots keep your perennials anchored and allow the roots to reach moisture and nutrients better. If you're unsure how much you're watering, you can put a rain gauge in the garden.

Mulch to Retain Moisture

Add a layer of loose grass clippings, shredded leaves or mulch around your perennials to help retain moisture in between watering. Mulch also keeps roots cool and prevents weed seeds from taking root in your flower beds.

Stake Taller Perennials

Heavy blossoms (such as those on peonies), wind and heavy rain can topple larger perennials. Look for supports to protect these plants and to keep blooms upright and beautiful. Tuck decorative fencing in front of plants, encircle them with foldout supports, or use ties attached to bamboo stakes and trellises to anchor plants. Even tomato cages can support towering flowers such as delphinium, hollyhock and hibiscus.

Trim Back Perennials

When perennials have finished blooming, snip off dead flower heads and stalks to prevent the plants from setting seed and to preserve their strength. Apply a slow-release fertilizer to keep foliage growing.

Do perennials grow back? Yes! Annuals must be planted each year, but perennials are plants that survive winter in their growing zones. Keep them healthy, and they'll return the next spring. In the fall, after the tops die back, cut stems to 3 to 4 inches above the crowns. The clump will send up new growth in early spring after being dormant for the winter. You can also snip off dead foliage and stems in the spring if you missed trimming them in the fall.

Prepare for Winter

If you're in a cold climate, mulch perennials with a few inches of material to insulate plants from freezing and thawing temperatures that can kill them — especially if a late-winter warm-up coaxes them to emerge too early. Remove mulch in the spring when the danger of frost passes or when you see plants beginning to emerge.

Divide Plants

Most perennials can be divided after two or three years. This keeps plants from getting overcrowded. The best time to do this is in the early fall after blooming, which is early enough for the plants to resettle and set new roots before winter. Mulch perennials heavily to provide winter protection. You can also divide plants in the early spring a few weeks after the leaves begin emerging.

Cut the crown of each perennial into several sections with a sharp knife, with each piece retaining its own root system. If the center portion of the old plant shows heavy, woody growth, discard it and replant the younger outer portions of the clump.

For more information about sharing perennials, check out how to divide perennials on the Burpee blog.

Written by Lisa Meyers McClintick

Lisa Meyers McClintick has been an award-winning journalist and photographer for publications such as USA Today, Midwest Living and Twin Cities Star Tribune for more than 30 years. She also has authored travel guidebooks on the Dakotas and Minnesota and volunteers as a Master Naturalist based in St. Cloud, Minn. Her home garden includes fourth-generation perennials, herbs, heirloom tomatoes, fruits for making jam and jellies, and a variety of hybrid and native flowers that inspire illustrations and photography.

May 18, 2021
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