Sometimes when we are growing new perennials, we don’t have an immediate home for them. For example, this year, we are expanding our subarctic rose garden and we grew a few other perennials from seed to give this garden a bit more character and diversity. This longer term effort requires removing sod and many, many hours of work that we have to take on over the entire summer. Like most Alaskans, our summer means turbo mode and we have a lot to accomplish in just a short few months.
So, the question then becomes how do we prepare those perennials for semi-long term life, prior to going in the ground?
We definitely borrow from commercial growers here, but the key is simply putting them into fairly decent size pots. We’re usually looking at a minimum of one gallon pots, but it could be more, depending on the perennial. We want to give them space to establish those initial roots, but not too much space that they can grow to their fullest potential. If you keep them in a small pot, they will do poorly and your planting flexibility will be greatly diminished.
Most years, we also buy a handful of bare root perennials as well. We also treat these this way, giving us a fair bit more time in the season to get to actually planting them. For example, we just planted a few of those bare root perennials last weekend, but we picked them up back in late May! Putting them into decent size pots bought us a couple of months of flexibility, instead of having to push ourselves further when we all ready had a ton going on in the early season.
At least where we are at, there’s very low chances of overwinter survival if these plants are kept in their pots over the winter. While you could bring them inside for winter, the plants we’re growing often require some sort of winter experience. Most cold hardy perennials need the insulation of the ground and proper snow cover to aid their survival. Almost all of our experiments with overwintering in pots have ended in failure, even if kept in our greenhouse. A greenhouse doesn’t do much at 40 below.
So, it’s important to get our perennials in the ground that season. When you offer those perennials a chance to put on roots, their chances of survival go up significantly, even if you plant them in the ground later in the season. We’ll often give our potted perennials a bit of fertilizer, just to encourage their initial root growth.
At least in subarctic perennials, we haven’t found an “ideal” time for planting them. Some say to do it early in the season, some say later in the season. We don’t think it matters that much when you do it, just that you do it that season. We’ve lost perennials planted at various times and had success when planted at various times. We do usually like to do it going into rainfall, just to aid in their watering and initial transplant care.
We are giving these milkweed a try. They are supposedly hardy down to zone 3, but we’re going to find out for sure! We haven’t found it particularly popular up here. But, if they take, we’re excited to increase our attraction for butterflies and milkweed is definitely one of the best ways to get there!
