Perennials are one of the best investments you can make in your garden. You plant them once and they keep coming back and blooming for many seasons. You have so many options to choose from in a wide range of flowering times as well as colors, sizes, shapes, and textures. To help you start and maintain your perennial garden, we’ve gathered these tips from Burpee’s expert growers.
Getting Started
Sowing perennials from seeds is the most cost-effective way to get a lot of plants without busting your budget. The Superseed Seed Starting Tray with 36 cells makes it easy to start and care for the plants, while the Seedlings Heat Mat ensures they are always at just the right temperature for vigorous growth.
Follow the packet instructions for when to start the seeds in relation to your last frost date in spring. Some types of perennial seeds may need to soak or be scarified (nick the seed coat) before you plant. Don’t skip those steps or your seeds may not germinate. Once they come up, set the tray under lights, such as the energy-efficient Fordhook LED light, which provides consistent light so the seedlings grow up straight and strong. When the plants are ready to go outside, gradually acclimate them to the outdoor conditions over a week or two, a process known as “hardening off,” before planting them in the garden.
Buying garden-ready perennial plants is easier and more reliable than starting from seeds, especially for beginners. If you order plants for delivery to your home, unpack them as soon as possible and water them well. Place the seedlings in a sheltered area with morning sun, keep them watered, and plant them within a few days.
Prepare the Garden Soil
Use a heavy-duty hoe or garden fork to loosen the soil and break up clumps in your perennial bed or border. Be sure to remove weeds and large rocks. Whether your garden soil is mostly clay or sandy, adding compost helps to balance the pH, manage moisture, provide a steady supply of nutrients, and gives new perennials’ roots the room they need to spread out. Work homemade or bagged compost into the top 6 to 8 inches of the soil in your bed. Mix in Organic Biochar Blend, a natural material that activates the beneficial organisms in the soil.
Dig Holes and Plant Gently
Use a spade to dig a hole for each plant that is 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 sprinkle about a quart of water into each plant’s saucer. Let it soak in and then add another quart of water.
Keep Your Plants Watered
Your seedlings grow best when they get 1 inch of water a week, either from rainfall or your hose’s sprayer hose sprayer. A deep soaking once a week encourages the roots to extend down into the soil. Deep roots keep your perennials anchored and allow the roots to reach moisture and nutrients better. Light, frequent waterings lead to shallow roots. If you want to keep track of how much natural irrigation your perennials are getting, put a rain gauge in your garden.
Mulch to Retain Moisture
Add a layer of mulch around your perennials to help retain moisture in between watering. Mulch also moderates soil temperatures in summer and winter and prevents weed seeds from taking root in your flower beds. You can use dried grass clippings or shredded leaves, both of which nourish the soil as they gradually decompose. If you prefer a more attractive mulch, try pine bark nuggets.
Stake Taller Perennials
Long-stemmed perennials with big, lush blossoms stay upright and look their best when you hold them up with stakes or cages cages. Peonies, dahlias, lilies, and delphiniums are popular perennials that benefit from a support system. If you prefer bamboo or wooden stakes, use stretch ties to secure them.
Trim Back Perennials
Use a pair of pruning shears to snip off dead flower heads and stalks after the perennials finish blooming. This prevents the plants from setting seed and directs their energy into storing resources for reblooming next year. 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 leaves, grass clippings, or straw 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. Uncover the plants in the spring when the danger of frost passes or when you see the perennials beginning to emerge again.
Divide Plants
When perennials become overcrowded, you can dig them up and divide them, making new plants you can use, swap, or share. The best time to divide perennials is in the early fall, which allows time for the plants to resettle and set new roots before winter. You can also divide plants in the early spring a few weeks after the leaves begin emerging.
To divide a perennial, use a sharp gardening knife, like the Hori Hori, to slice the crown of each perennial into several sections. Each piece should have a section of roots to regrow after you plant it. If the center portion of the old plant is heavy, woody growth, discard it and replant the younger outer portions of the clump.
For more information about sharing perennials, check out our guide to how to divide perennials.