We’re going to talk about and show you one of the precautionary steps that we take to aid our perennial’s survival through our bitter and harshly cold winter!
As you can see, we cover our more vulnerable plants in a layer of straw. We usually aim for about 3 to 5 inches or so. We can cover individual plants or entire beds, whichever is most appropriate for what we are trying to protect. Though we don’t have scientific evidence to “prove” this works, we’ve collected more than enough anecdotal evidence by having our perennials survive temperatures well below their preferred zone.
Now, we don’t perform this across all of our perennials. In particular, we’re interested in protecting our zone 3 perennials since we can sometimes get conditions that go below this. (-40F and colder.) Another prime plant that we want to protect are first season perennials. Doing what we can to make their survival just a little bit easier goes a long way in helping them to survive their very first winter. Second year perennials are much more likely to survive, given the additional maturity.
Sometimes we do this to our particularly “valuable” perennials, like our strawberries. Technically, our strawberries are sufficiently hardy to survive our winter. But, it would be devastating and expensive to lose our crop! We also recommend doing this to garlic beds, which are planted in and around first frost up north here. This aids them with surviving the cold winter and especially helps the soil thaw more quickly in the spring.
However, we don’t bother with some plants. Things like chives, rhubarb are left on their own for survival. These plants are absolutely hardy enough to go down to -50F and below. But, with others like our perennial food forest, we want to make sure they can survive even our most brutal winters unaided. We can’t be coddling them along their entire lives! In a way, they have to prove their worth to be valuable to us.
The way this works is not by the straw itself providing insulative value, in fact it’s kind of a “crummy” insulator. What happens is this builds an air barrier between the snow and the soil. Once the snow fall occurs, we effectively get three layers of insulative protection for our plants. The snow, the air/straw barrier and then the soil itself. Material transitions are what insulate well, forcing the cold to “work” to get into our plants.
You might think this use of straw as wasteful, but we toss every bit of it into our compost piles the following spring. This material often helps us get a head start on our compost in the spring, once we mix it in with our existing compost. Sometimes we also leave a very light layer of straw on our soil, too, aiding in keeping down weed germination. Straw is getting surprisingly expensive for us these days, so it’s important for us to maximize our value from it.
The timing for this isn’t super important, just sometime before winter sets in. Snow on the ground is fine. We’re really trying to protect against those “deep winter” temperatures here. As for when we remove the straw, it’s as soon as things start warming up. Usually “first green” is our sign, we want to get the straw off and allow photosynthesis to occur as soon as possible.
We’ve been doing this enough years now to know it works and to highly recommend the process to others. Just last year, we easily had 100% survival of our zone 3 plants despite diving well into zone 2 temperatures. We were worried, but turns out we didn’t need to be! All thanks to this protective process!
