On Monday I talked about deadheading petunias. Petunias are definitely an annual. No matter your climate or zone, they do not live forever. If you live in a zone with four seasons (why they call these the “temperate” zones, I’m not sure because the winters we’ve been having lately are anything but temperate–but I digress. That’s the terminology they–and we–will use) and tried to bring petunias into the house to winter them over, you would not have much success.
Perhaps you’ve tried this with herbs. Again it’s somewhat easier to explain (at least to anyone who has grown or tried this with herbs). Basil, a true annual, cannot be over-wintered. It just gets long, leggy, and keeps trying to set flowers and go to seed. It does not make the nice leaves one needs for cooking.
Other herbs like rosemary or bay which are perennial (but cannot be over-wintered outside where temperatures drop below 20 degrees farenheit, with certain exceptions) do just fine in a cool place over-winter. These herbs, as well as other plants which we may bring in, are known as “tender perennials.”
I find a lot of gardeners winter things over but are not necessarily familiar with this term. It really doesn’t matter, but it does get confusing. I’ve had seasoned professionals say to me that they winter their annuals over every year.
Well, no. Clearly, annuals, because of their life cycle, as discussed, can’t be wintered over. What they technically mean to say is that they are wintering over their tender perennials. And while it may sound as if I’m splitting hairs here, I’m just trying to help all of us not born with this knowledge understand a little better the life cycles of plants. Because, after all, if annuals only live one year, (more or less), while perennials are perpetual (more or less) (an easy way to remember which is which when confronted with all those rows of plants at the garden center) you want to choose those which suit your needs.
Tender perennials are a huge group of plants. They can be house plants, they can be sold as annuals, they can be sold as biennials (don’t even get me started on those) and they can be sold as something else entirely. The herb ocimum basilicum Pesto Perpetuo–or Basil Pesto Perpetuo is a tender perennial here in Connecticut. It is a “perennial” basil in the sense that it does not set seed and die in one year–so it may be over-wintered. But our climate doesn’t permit that to happen so we would have to over-winter it indoors. Still, it’s quite a blessing to have a basil that will grow indoors over the winter!
The photo above consists solely of “tender” perennials. These are things that if I lived in another climate, I might be happily growing outdoors year round: a lemon tree, amaryllis, lots of pelargoniums (geraniums). I have lots more as well. Perhaps the classic example of this in my climate is the edible fig. Here we have to bring them in, or bury them to protect them. They are not hardy.
Here’s another classic case of what I mean. This unusual plant is being sold as the annual “digiplexus.” There’s an unlovely name for a great plant. What it technically is is a biennial foxglove crossed with a South African foxglove. So if you live in Zone 8 or south, it’s hardy for you. For the rest of us, not so much. And unlike the biennial foxgloves which might self-sow, this is a hybrid, so it most likely will not.
Anyway, the color is great and it went nicely with some perennial agastache I had just planted. And it should keep blooming because of the South African parentage. We’ll see.
As the Spoiler always says, I garden in the wrong climate.
I hope this clears up a bit of the mystery for you about tender perennials. You don’t ever have to use the term. Just know what it is–and why some of your “annuals” will live over the winter in the house and others will not!