Summer’s heat and regular rainfall leads to exuberant growth of many flowering perennials, which may lead to floppy, leaning and collapsing plants. Climate, plant selection and other conditions may indicate the need for physical support in the perennial garden.
While some perennials are inclined to droop naturally due to weak stems or heavy flowers or buds, others take a dive when a strong wind or heavy rain weighs them down.
Overfertilizing plants also can cause weak stems that simply cannot support their own weight. Lack of sunlight makes plants reach toward the sunlight, causing leggy growth that may obstruct walkways or cause damage to neighboring plants.
Most perennials do not require any help standing up straight, but occasionally the need arises. When done correctly, staking and supporting perennials creates a hidden infrastructure that can prevent plants from falling over, or save a threatened plant from breaking or being damaged.
Ideally, gardeners should plan to support perennials that are known to droop or collapse early in the season before new growth emerges. Clump-forming or weak-stemmed plants can be supported with grow-through stem supports that are made of plastic-coated wire. Position the legs of the support over the crown of the perennial and insert them into the soil. A circular or square grid will support the stems as they grow up and through the support.
Perennials such as garden phlox, blanket flower (Gaillardia grandiflora), rattlesnake master (Eryngium yuccifolium), goldenrod (Solidago sp.) and annuals such as tall zinnias and snapdragons are prone to fall over, and can benefit from a support system.
Ring-style supports are similar to grids, having two or more concentric rings to support outwardly sprawling clump-forming perennials such as ornamental grasses, asters and yarrow. Place over newly emerged plants to keep them tidy.
Similarly, these sprawling plants can also be supported with a simple chicken wire cylinder pushed into the soil around the plant. The spreading nature of these plants will quickly overtake the wire, concealing it from view.
Perennials at the front of the border can quickly overstep their bounds, obstructing sidewalks and paths, and becoming vigorous enough to damage their neighbors. Linking stakes allow gardeners to encircle or restrain plants by using as many stakes as needed to control the problem. Plastic-coated metal linking or “y” stakes can be used to create a supportive boundary for plants such as Shasta daisies, lilies, crocosmia and any other plants you may need to control.
Gathering rings, or flower rings, are simple metal stakes with a loop at the top designed to support single flowering stems that need support and are great for emergency staking of wind-toppled flowers. I have used several of these with soft twine in lieu of linking stakes to encircle a storm-ravaged plant that needed support, and to keep plants off the sidewalk. Gladiolus, bearded iris, hollyhocks, large flowering dahlias and zinnias can be supported with gathering rings.
Thunderstorms often create the need for emergency staking. Sunflowers do not typically need support, but after a storm, you may need to keep the keep the flowers from toppling.
Bamboo poles make excellent upright supports for all types of annuals and perennials. Tie tall plants gently every foot or so with 3-ply twine or cut pantyhose, being careful not to cut or damage stems.
Stakes and poles should not extend above the height of the plant to keep them hidden from view. Care should be taken to avoid damage to roots when inserting supports, stakes or poles into the ground.
If you missed a chance to place a grid over a perennial early in the season, you can fashion a makeshift grid with bamboo poles cut to height. Push them in around the plant and weave a grid carefully through the stems.
No bamboo? Try cutting twigs to create rustic-looking stakes and poles. In a perfect world, perennials would never need staking. Improve the odds by pruning late season bloomers by a third, now through mid-July. Sedums, swamp sunflowers, and late flowering asters will remain bushy and upright with a light pruning.
If you notice a perennial collapsing from the center outward, it may be time to divide and replant this fall or next spring. If you are not sure when to divide your perennials, check out the Clemson University Home & Garden Information Center fact sheet “Dividing Perennials” HGIC No. 1150.
Amy L. Dabbs is a Clemson University Cooperative Extension Horticulture Agent and Master Gardener Coordinator. Send questions to firstname.lastname@example.org.