I’m trying to read on winter storage for potted plants, in specific for an area where winter is truly cold. I keep reading about unheated garage storage but on the very next sentence the authors go on about how even an unheated garage stays about freezing all winter long. Yeah, about that… I can see -25f in the middle of the winter and my garage is detached, if it would stay above freezing I would be there on shorts and a sweater.
In previous years I keep them outside on an empty raised bed next to the house. I cover them with snow and pretty much let them be until it melts in the spring, sometime mid May. Even among the hardiest there is a good amount that won’t make it not just because of the temperatures but because I suspect spring comes, top melts, bottom is frozen thus water can’t move, they probably just drown…
I do have a garage, I am planning on moving them there to keep them out of the 45mph winds and the usual January meltdown. They will be frozen solid like popsicles. Should I put a layer of water on the pot which will turn to ice? Keep them in the dark? I figure if I keep them protected for the worst of the winter (Dec~March) I can move them out in April so they can wake up sometime in May when the weather warms up.
Evergreen plants should be hydrated well before storage. If there is no air or heat or wind, not necessarily a need to add moisture in winter, especially if cold.
But,
I’m not accustomed to Alaska conditions, so maybe somebody closer can help you.
These are not evergreen, nor necessarily plants that are meant to stay in pots. These are cuttings and rootings of cherries, haskaps, currants, and miscellaneous plants with about half a season of growth on them. The intent is to give them the best chance to overwinter. As each year I am raising the numbers (between 100~150 starter plants to overwinter this year) I’m looking for better methods and better chances for the plants.
Speaking of better methods; does anybody knows of a good resource on overwintering bareroots? Everything I find is more related to (“If you can’t plant them right know do this”) as opposed to the art of preparing bareroots in the late fall for storage and eventual spring use. Heeling them in soil is not that great an option when the temperatures hit -25f and the frost line is 4 1/2 feet bellow them.
Eventually I want a root cellar to store honest to goodness roots but with our frost line and rocky soil that isn’t happening soon. Still, I could do a smaller proof of concept if I can sort out air circulation and similar requirements.
I’m in 7A (seems like it is closer to 8 or 9 in terms of recent winters) and use a detached, single-car garage for figs in containers, etc. Obviously very different from where you are. But I do think there is more to it than minimum temps.
The garage is over 50 years old and isn’t very tightly sealed.
I have a min/max thermometer I leave in there to give me a good idea of how temps range, so I know for a fact that my garage gets below freezing in the winter and I’ve seen low 20s inside. That was a few years back and was rare, but it definitely gets below freezing at least a little bit each winter. I’ve opened the garage a few times when the day warms up after a cold night and tested with my finger and rootballs are often frozen, particularly smaller ones like 1 gallon rooted fig cuttings. But come spring, I’ve never seen even the slightest winter kill on the tips. If left outside, these smaller potted figs would have probably died or at least died back to the ground at temps in that range.
So I think part of the benefit of the garage is that it greatly slows the freeze/thaw cycles and protects the branches, etc. from the dry desiccating winds. While I wouldn’t want you to put all your plants in danger, I think it would be worth experimenting to see if the buffering effect of the enclosed space of your garage would be enough to winter over some of your plants, since the ones you list are pretty winter hardy and I’m sure they would have roots frozen solid if planted in the ground so maybe an enclosed garage would be enough?
Last winter i buried most of my potted plants in the garden. It is a pain in the butt. I also overwinter trees in my attached (not heated) garage and they do fine in there (all those trees flowered/fruited–while outside peach/nectarine trees had zero to no blooms). I wait as long as i can to move stuff into the garage. Usually December…once overnight temps look to drop below 0F i make the move. Mine freeze solid. They are giant blocks of ice in the dead of winter. I move them out as soon as i can in the spring to get them thawed and moisture back in the roots.
Overwinter your bare-root the old fashioned way. Dig a trench outside, mark the trench ends with sticks. Put in your bare-root horizontally and cover with soil. Keep the plants all the same way so all roots on one end and tops on the other end. After soil freezes, cover with straw. Do not straw until the ground freezes as you do not want to invite mice. Dig them up carefully next spring. Pretend you are an archaeologist while digging them up and go slowly to prevent breaking any.
I have done this overwintering potted tree roses in southern WI. Works great!
I’ve tried wintering in a cellar the past couple of years. I works ok for the hardier plants but is a hit or miss for the more tender plants. It must have gone down to -5 or even -10c (I don’t know how much that’s in pounds or miles) and that’s way too low. A garage I imagine gets way colder.
What some nurseries do, is leave the pots outside and turn them on their sides before freezing. It’s important not the let them get soaking wet if you do this.
I do like the trench idea though. Might give it a Shot this year.
tried the garage thing here. they all died. best thing is what others said. put in ground or maybe put them all together in a protected spot in the yard thats mostly shaded. cover with straw, insulation. whatever you can find and bury them in as much snow as you can. here we have enough snow they stay protected until at least the 1st week of may. but anything less than z3 hardy wont make it in pots. z4 strawberries in a planter die off every winter.
I usually have a wide assortment of small and larger potted plants to winter over. For several years I did the outdoor trench technique and it worked quite well. Then the voles discovered the buffet. Now I have screened off an area in the crawl space under my house. The sides are insulated so the area stays between 32 and 45 degrees, with a few dips below freezing each year, but usually less than a night or two. It has limited headroom (about 44 inches) so I lay taller plants on the side. These pics show the plants I pulled out last week, after being in the dark storage for 4 months. The Poncirus ‘Flying Dragon’ dropped its leaves in the fall before storage, same for the figs, which may have been cut back as well. The Olive looks just the way it did going in. My next upgrade would be an insulated shed so I could handle things while standing up, and a minimal source of heat and some fans to hold a more steady temp in the mid 30’s. It’s more of a problem to keep it cool enough rather than warm enough.
before I had the hoophouse I put them in the coldest corner of the basement, there’s a drafty window in that room. and covered them with a shade cloth to keep light out. they go from 45-55F in there, stuff that needs chill hours wouldn’t get it but figs, olives, stayed just fine
