Hello everyone,
I live in zone 5 and am growing blueberries all rated to zone 4. I’ve heard some people online say that you need 2 zones of hardiness extra when growing in pots if you want to leave them unprotected.
Is there any truth to that?
Thanks!
I would say Yes. Surround your pots with shredded leaves to 6 inches above the dirt level. They will be fine.
Thank you! Do you think putting them up against the house will help keep them warmer?
That would help a lot on the sunny side of the house.
Another thing to consider is rain in winter. I’ve had them turn into blocks of ice in the pot after a rain. Some plants don’t do to well after that.
Very good to know! I think keeping them next to my house under the roof should help but Ill also shelter them with a water proof tarp. Thanks!
At -5 you’re definitely safe…minus 25, probably better to be safe than sorry.
I never get concerned about the roots becoming an iceball…that can happen at 15 degrees.
Good to know! I’ll be keeping them outside unless things get crazy out here. Thanks!
I am zone 5 and have grown in pots outside for a few years. I have grown things hardy to my zone and not below and my plants still survive. In fact only time I had issues was when I fallowed what some say on the internet for keeping plants over winter. I was told to water them before it snows but I believe that killed them. Once I planted and did not water over winter my plants did great. Then again we have not gotten below -9 and I am buying plants hardy to zone 5 though because we are supposed to be zone 5.
Thank you very much! Thats definitely a relief to hear. I think I’m still going to protect them a little bit but this gives me some peace of mind.
It is worth noting not all pots are equal for overwintering though I should say. Something everyone states that has merit is terracotta or other clay pots suck for overwintering. I have had success with grow bags and plastic but in my terracotta pots even zone 3 plants have died. Blueberries have some tough conditions for winter in general depending on where you live though. For my area it is not really the cold that kills them but the dry winds. You can see the CSU extension video on how much length they went through to overwinter blueberries here in CO.
Thanks again. Luckily mine are all in grow bags, I’m a bit surprised they’ve worked better than tetra cotta for you. In either case, I’ll be putting my blueberries against my houses wall and covering them with a water proof tarp which should give good wind protection as well.
The soil in pots/grow bags deep freeze more easily than plants in the ground, and also plants in the ground often have a way greater root system, the more of the total mass of roots that don’t freeze the better. Also pots/grow bags can de-freeze much faster than in ground plants, the soil de-freezing too fast can damage plants as well.
There was a guy on the old Garden Web,now Houzz I guess,who lived in southeastern Washington State,probably Tri-Cities area.He said his Blueberry plants froze solid in half whiskey barrels every Winter and came back the next Spring.