If you're just learning to tell Echinacea (coneflower) from Echinops (globe thistle), shopping for perennials can be quite an overwhelming experience. As with purchasing groceries, it helps to have a list; if you don't, you're likely to come home with impulse buys for which you have neither the space nor the right growing conditions.
You can buy perennials in a variety of places—from garden centres to grocery stores to home centres and big boxes.
Generally, you'll pay a little more at specialized garden centres or nurseries, but you'll also find more selection, plants that are better cared for and more knowledgeable staff.
Novice gardeners often make a beeline for the perennials already in bloom because they look beautiful and it's easier to decide whether one works with your colour scheme. However, this means the plant's blossoms will be spent more quickly in your garden. Personally, when I have a choice between a perennial in full bloom or one that's just beginning to bud, I pick the latter: I want the flower to bloom in my garden, not at the store.
When planning your garden's “flowering schedule,” it's also important to keep in mind that many nurseries coax perennials into early bloom before the plants would normally flower. The next season, your perennial will bloom at the typical time for that species, which is usually slightly later than when you bought it (normal bloom time is usually written on the plant tag).
Beware of bloom times
While shopping in the spring, remember that if you buy only what's in bloom, your garden will likely be finished by mid-July or early August—even though there are a couple of months of warm weather yet to come.
Most perennials flower for only two to four weeks each season, so to create a satisfying flower garden, do your research and shop for plants that bloom at various times. You can then enjoy a floral display from spring right through to fall.