(This post was updated on May 18, 2020)
When is a perennial not a perennial? One of our readers pointed out that collard greens are not perennial, although we included them in a list of vegetables that will regrow from year to year. That raised a rather vexing issue, which we thought was worth further exploration.
Although scientifically a plant may be classified as annual, biennial or perennial, in practice there is a lot of grey area. And, to answer conclusively whether collard greens are considered perennial or not, can be a frustrating exercise indeed.
Technically speaking, our reader is right: collards are not perennial but rather biennial. However, in certain areas, they act like perennials.
“It has to do with where they’re being grown,” says Heidi Carmichael, trial horticulturalist with Vesey’s Seeds in York, Prince Edward Island. “In areas where winters are milder, there is a higher chance of them acting as a perennial.”
So, under good growing conditions, if you leave the plants, Carmichael says they will self-seed and come back the following year. On the other hand, in years with a colder winter, the plants may not come back at all.
“Certain varieties will probably be more viable than others,” says Carmichael, who field-tested a slow-bolting variety of collards called Flash at Vesey’s a few years ago.
Horticulture supervisor at the Halifax Public Gardens, Bev MacPhail, says collards are well suited to the Canadian Maritimes because they will take cold weather and can be harvested during the winter. “Especially if they are given some protection,” she says. In fact, MacPhail says their flavour is actually enhanced by frost.
Many gardeners choose to grow collards as an annual, which ensures quality of taste and vigourous growth. But technically, “they are a biennial, so will go to seed in the second year,” she confirms.[If you’ve had a ‘perennial’ experience with collards, we’d love to hear from you. Leave us a comment — Ed.]