Overwintering new apple grafts

So my dozen or so grafts from earlier this spring are doing well but still in their pots in the greenhouse. I never did plant them outside as I decided that in our winds they could use a year to strengthen the graft before having to face the elements. So my question is how best to overwinter them.

This greenhouse is heated during the winter (a few citrus trees live there), so temps may never get really cold enough to induce dormancy (not below freezing anyhow). Right now on sunny days the GH is at 90F+ (temp the ventilation thermostat is set to). And these trees have lost a few leaves, and a few more have turned brown a bit, but they are no where near as dormant for the season as my outside apples (which have been mostly bare of leaves for a while now).

I am concerned that inside the GH it may never be cold enough to “take” them thru a winter. I was thinking of putting them in the attached barn, which is unheated more or less (gets some waste heat from the GH on sunny days) but goes below freezing most every night. Seems like a better winter place for them, what do folks think? And if I do use the barn, how should I be transitioning the grafts from the GH to the barn?

I’d remove them from the pots and put them in their final resting place. They will be fine over the winter and that will give them a good leg up on next year’s growing seadon

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I agree I would stick them in dirt in the yard; if you’re afraid of a freeze on tender growth you could probably start putting them in the barn at night and bringing them outside during the day for two weeks or so to harden off and/or just throw them in the barn for the winter but watch out for mice and rats

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If I were in zone 5a like you are, I would not plant in ground now. If you do, mulch well and thickly. There are people who plant trees in ground this time of the year. Considering your zone, I personally would not do it.

I overwinter my potted plants in an unheated basement but temp does not below 20 F.

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The other thing you could perhaps do is harden off in the barn, then lay them outside in a trench and cover the whole bundle under a foot of dirt to protect them…

Thanks for the ideas guys.

Outside here is not really viable. I long ago stopped doing any sort of fall planting, just too dry, windy and variable here. We’ve had <1/2" of rain in the last 4 months with little sign of the drought breaking soon. And 100+mph winds generally happen every winter, several times. My success rate for fall planting is like 20% or less.

While I like the idea of healing them in, That too could be iffy here, between the weather and rodents (which seem to be especially hungry this fall no doubt due in part to the drought).

I think the barn might be the best choice. It is unheated (except for the attached GH), with no insulation so it does get cold at nite. My basement is effectively heated by two large south facing windows, it is typically 50-60F in there during the day. The trees would be protected from the wind in the barn, and I can control the temp a bit by moving the trees from a more interior spot to closer to an outside wall or the overhead door (although I’d rather not be moving them around all the time). One other possibility for storage is a small “root cellar” we have (actually an insulated room in an underground corner of the barn foundation). Not ideal in that it won’t go below freezing (have potatoes and onions in there), and the trees would end up taking over the little floor space left; but if it was the best choice…

Just curious how people keep their potted trees overwinter in a barn or basement. Do you just check for water every few weeks? Need to cover the pots with mulch? Need to keep it dark?

I overwinter my potted figs from around Thanksgiving til late March/early April. I don’t mulch them but I put a thin layer of sand on top of soil to prevent fungus gnats from emerging.

I just stick my finger about an inch into the soil to see if it is dry… I water them when the soil is dry.

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I agree. Zone 6 or higher is fine for fall planting apples. Lower than that is risky.

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Very risky.

I have a greenhouse that I keep at 34 overnight all winter. During the day and it’s sunny here a lot of the winter the temps can skyrocket. I see 70’s all the time on any given day during winter. You really need to have the greenhouse somewhere at or below 40 I suspect (total guess re:40F.) You’re wasting money heating it anywhere above 33-34 really if your goal is to overwinter-only/grow seed. Heat it up to 50 or 55 if you want to graft. I like 55F for grafting.

The other half of the story is this… dormancy requirements are met at two weeks. That I am 100% certain of. So should you be able to keep your potted trees outside for a stretch of two weeks where temps are in that 28F to lets say 37F zone, you have met all the requirements and you may now take the potted plants somewhere where roots are not being damaged from temps dropping below 28F. 28F is another magic number.


I planted all my grafts in large pots, in the ground. I dug a trench deep enough for the pots and keeping the grafts above the dirt. Then I back filled the trench and will pull the pots out in spring and decide what to do then. All the pots are very large so I’m not concerned about root growth. Will let you know how they turn out.

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I have 5 trees, 2 successful grafts and 3 bud9 rootstocks in little 1 gallon pots.
I don’t know what to do with them. I don’t know where I want to plant them…
My basement is heated so no luck there. I guess I’ll set them beside the house and
pile them deep in mulch?

@Barkslip The GH heats itself on sunny days, easily gets to 90F+ even with <20F outside. I do have a system to capture some of that heat but usually vent some excess. The backup heat is set to 40F, to keep the citrus and a few tomatoes and peppers alive and going thru the winter. The GH is not just for the grafting experiments (but the mix of things in there does make it hard to keep everything happy). But even with the backup heater off, it would still get quite warm during sunny days, so not really viable for the dormant apples, I don’t think. Good to know that a couple of weeks outside on the N side of the barn will meet the dormancy requirements; I will be using that if it doesn’t get consistently cold enough in the barn itself.

@Daemon2525 Unless you have some very active cats, I’d put metal screening of some sort over those starts before burying them in mulch otherwise the rodents will be eating them over the winter.