Growing containerized shrubs has been sort of a game-changer for me. There is something about them that is stately, and while I love containers full of annuals (like, a lot) shrubs add a little something different to the palette.
The problem with growing shrubs in containers, however, is winter. You invest a bit of money and a lot of time into getting a shrub to grow in a container and all of that is only worth it if it lives for several years.
The rule for overwintering things in containers is that it’s safe to leave them out in a freeze-proof container if they are two zones hardier than the zone in which you live. But you can cheat the system, which is what I’ve done. I grow shrubs—a ‘Green Mountain’ boxwood and three shrub roses—in containers but they winter in the unheated garage.
I’m fortunate to have a bit of light coming through the windows in the garage, which helps keep the boxwood happy, but the roses, which are completely dormant, could care less. Beyond moving them into the garage, there’s very little winter care that’s called for.
Like most plants, containerized shrubs will be in better shape if they go into winter well watered, so the day before I move them into the garage (with the help of a very sturdy hand truck I borrow from work) I give them all a really good drink, until there’s a lot of water coming out the bottom. I check them in mid-winter and add a little water then as well if they seem dry.
The roses will also get a little shredded leaf mulch on top for a little extra protection that breaks down easily in spring.
They were moved into the garage just a couple weeks ago, but they could still be outside. We’ve not had temperatures much below 30 yet and frankly, the longer they can stay outside the better. But I like to get the yard buttoned up in case we get an early season snowfall so they get moved perhaps a little earlier than necessary. The point is, you don’t have to be in a huge rush to get them put away.
Care during the growing season is equally simple. Treat them like anything growing in a container: water thoroughly but not necessarily frequently. I usually water about once every 4-6 weeks. In spring I scrape off the top few inches of soil and replace it with a nice layer of compost. Since I started them all in large pots, I don’t anticipate having to repot them, but at some point I may have to pull them out, refresh the soil and possibly do some root pruning. Shrubs growing in containers probably won’t live as long as shrubs growing in the ground, but I promise you you’ll get your money’s worth.
And that’s it for care. It really couldn’t be much easier. In fact, the most difficult part of the process is the physical moving of them since they are in pretty big pots. It takes two of us to lever them onto the hand truck and make sure they don’t roll off on the way to and from the garage. But if that’s the most difficult part of growing a plant, I’m all in.
17 Responses
Hello Erin,
I live in zone 5a southeast Wisconsin as well. Bought one too many baby gems during our patio landscape project this spring and would LOVE to plant this one in a large container. I already winter a small japanese maple in the garage over the last 2 winters and its doing g great. Thanks for the tips! Do you think, a baby gem would winter well in the garage as well? Only has one east facing g window. Thanks!
Erin,
We have green mountain boxwood in containers on the 12th floor of a condo building. How often should these be watered.
Thank you
Jo-Anne
how large is your container for shrub roses? what about iris?
Good question! One is 18 inches and that rose has been in there for I believe three years, possibly four. The two new ones are in 22-inch containers. I would say 18 inches is probably the minimum because you really do need a volume of soil. I think you could go smaller for irises, because you’ll be dividing them with some regularity.
thanks. I’m looking for 22″ pots but they all get a little narrow. Would a wider 18″ be better than a shallow bottomed 22″? I live in a zone 4-3 “ish”. I’ve read where you can line container with a plastic bag (holes in the bottom) then remove the plant from the container and bury through the winter. Any thoughts on this method?
Well done. Our garage would be a good place to do this but it is too small with all the vehicles etc in it. ha… I live dangerously. I leave my potted shrubs outside but I do move them into a area that the wind doesn’t just batter them. 6A is my zone so not so cold as your area.
We finally planted out our boxwoods but I love the way they look in containers. Our garage is not as good a winter home as yours. Much darker for one thing. But I keep thinking of trying something other than Hostas in pots again. Maybe finding a spot where I can plop them in the ground outside for the winer. That rose is gorgeous.
Yep … the ground plop works great too.
I am (luckily) in zone 6a but still have some treasures I overwinter, like a fabulous brugmansia and agapanthus. Unluckily, I don’t have a garage so we haul them into the basement. What we’ll do for love!
PS My first comment tho I find your blog first rate!
Thank you so much for taking the time to comment, Elaine! I will tell you right now, I’m envious of your agapanthus. I keep thinking I should attempt one one of these years but I haven’t yet.
I’m in zone USDA-4 and have small front and back yards so movable shrubs is an excellent idea I didn’t think they would survive the winter in pots but by bringing them in the garage well watered I can see no problems. Looks like you have a Proslat wall-mounted storage system. I don’t know how I would store all my gardening tools without it. Thanks for great gardening advice.
Serge, Ottawa, Ontario
That storage system is definitely a lifesaver. Our garage was such a mess before we got that. Thanks for stopping by, Serge!
I love your boxwood! Mine is in the ground and actually survives. I’ve been wondering about overwintering a few roses in pots. My garage is unheated. Are mice a problem? Ann
I’ve never had a problem with mice and I since there are definitely signs that mice and squirrels spend some time in the garage in winter, I would think I’d have seen a problem by now if I was going to. You could always put a cotton ball soaked in peppermint oil or a really stinky dryer sheet on the top of the container which should be enough to discourage them from taking up residence there.
Love this idea, Erin . . .as if I can’t come up with enough on my own?. I am going to try this with a couple of hydrangeas which are not performing as well as I had hoped. I’ll start by potting them up in spring-that is if they make it thru the winter. If they don’t make it, well, then, I will buy new ones!!
Always a good opportunity to buy more plants, right?