Question: I'm noticing that there are several periods between spring and late fall when there's just not much going on in my perennial garden. I'm starting to look for plants that will bloom during those times, but finding ones that are the right size, bloom the right color and match my site conditions is making my head spin. Is there an easy solution?
Answer: Absolutely—here are three solutions from which to choose. And they aren't mutually exclusive—you could try two, or all three!
1. Incorporate annuals. Many annuals bloom from early summer right up to the first frost. Plant long-flowering annuals among your perennials to provide consistent bloom. To cut maintenance, look for "self-cleaning" varieties that do not require deadheading.
2. Speaking of deadheading—do it to your perennials. Many perennials will offer a prolonged bloom period if flowers are removed as they start to fade. The plant's goal is to create seed. By removing the spent flowers, you redirect the plant's energy to make more new flowers rather than set seed.
3. Choose perennials with interesting foliage. "Interesting" might apply to the texture, size or color of the leaves. By making sure your garden includes a mix of different-looking foliage, you'll eliminate those periods when it looks like a blanket of green. Colored foliage is particularly useful in this strategy. A few examples of perennials grown mainly for their eye-catching foliage: hosta, coralbells (Heuchera cvs.), ornamental grasses, piqsqueak (Bergenia cordifolia) and ornamental rhubarbs (Rheum and Gunnera spp.).
A final tip—be a little wary of "reblooming" perennials, which are said to bloom in spring or early summer and then again later in the season, particularly if sheared back after the first bloom. Just keep in mind that for many, the second bloom is more sparse than the first. It will make a nice addition to the late summer garden, but don't rely on the plant to offer the same amount of interest that it does in spring.