Some perennials don’t stand up straight on their own.
It’s maddening but true. Many shasta daisies, tall Sedum, Baptisia and a host of other perennials get tipsy as the season progresses – stems elongate, flower buds become heavy and spindly stems bend to the ground. Either the outer stems fall or the whole plant splays out, squashing its neighbors and leaving a bald spot in the middle of the plant.
It’s usually brought on by a dry spell followed by rain (or over-watering), or wind + rain. And some plants are just prone to it even in the best of conditions.
Many seasoned gardeners simply avoid plants that splay, searching perennial tables for simliar-looking plants with sturdier stems. Other tricks to prevent perennials from flopping:
- provide plants with enough sun – most plants that lean are leaning towards the light they’re lacking.
- amend soil to improve drainage. Heavy clay soil can cause plants to root shallowly to avoid root suffocation. Adding organic matter or pumice can improve drainage so plants send roots down deep into the soil.
- don’t overdo fresh compost or fertilizer – overly rich soil (=high in Nitrogen) results in lush, squishy growth which topples easy.
- provide steady water – many perennials tip when they receive water after a significant dry spell. Cells plump up with water and weigh down stems, causing toppling. Water sitting on large flower heads can also weigh them down – use drip or hand-water roots.
- flopping can be a signal that it’s time to divide perennials. If the clump is starting to look intimidating, it’s probably time to divide.
- most importantly: when planting tippy plants, use nearby plants for scaffolding. If you have a tall daisy that flops every year, surround it with stiff, upright perennials like Aster divaricatus or erect ornamental grasses like Miscanthus sinensis that will help support the sides of the stems.
- most perennial plants can be pinched or cut back early in the season to encourage shorter, stronger stems. See "The Well-Tended Perennial Garden: Planting & Pruning Techniques" by Tracy DiSabato-Aust (Timber Press). This book provides detailed instructions on tip pruning perennial plants to prevent splaying and leaning. While the technique can sometimes delay flowering, it can be quite nice to enjoy flowers a little later in the summer.
And now, back to the present: what to do with floppy perennials now?
For perennials under 2 feet, try making a lattice fence comprised of 2-foot long slender bamboo twigs pushed deeply at a 45 degree angle in the ground, criss-crossing each other. It usually suffices to hold up the first foot of stems. This is the least obtrusive solution and you can barely see it when done with care. You can just make the little lattice fence on the side that needs to be propped up.
A similar idea: pea stakes. Pea stakes are small, forked twigs about 1-2 feet tall that you push into the ground. I like to harvest branches from hazels, dogwoods, and manzanita – the gnarlier, the better. Pea stakes work great for lax, airy plants 2-3 feet high, like Clematis recta and low-growing sweet peas.
Need something taller or more sturdy? Try bamboo or 1×1 wood stakes and twine. Rather than circling the plant with twine (use green garden twine or brown jute), which can make the plant look strangled, criss-cross the twine through the stakes and stems to provide internal support, cat’s cradle style.
Don’t have time to fuss with stakes and twine? Buy commercial metal stakes – there are many kinds. For single flower stems of plants like lilies, try the single stake with a little loop at the top to capture the stem. (Plant in full sun, though, and your lilies will rarely flop.) For a leaning perennial clump,try the linking metal stakes, which allow you to encircle the plant section by section. (The peony cages and commercial "cat’s cradle" style supports are best set up in spring when plants are just a few inches high; trying to stuff bunches of foliage into the hoop is a challenge – and results in a pretty bad look – at this time of year.)
Part of the problem with using unobtrusive, thin stakes is that you might not see them while gardening. Poking one’s eye out on a sharp stick is not said to be fun and it happens more than you might think. Ask an eye surgeon! In England, you can buy all kinds of rounded stoneware and terra cotta safety tops for stakes, designed to prevent eye damage. I would suggest exploring all the cultural tips to prevent floppy perennials before resorting to stakes, especially metal ones.