Hi everyone,
I'm in zone 5b, where winter temps often are below zero. I'd like to get a very large container that would remain outside year-round. Any suggestions as to what to get?

I am hoping to grow amsonia: Blue Ice bluestar, which I grew successfully in the ground---too successfully! It was spreading by underground runners, and I was having trouble keeping it confined. It has a very pretty blue flower, though, so wanted to try it in a pot.

Blue Ice bluestar:


Thank you for any suggestions!

From a 'Fine Gardening' website: "Fiberglass, lead, iron, heavy plastic, and stone are the best weather-resistant containers to use"

I've seen at the Big Box stores these pots that look like old Italian pots made of stone but when lifted, it's surprisingly light as it may be cast resin. I would think those would hold up. Definitely make sure there's a hole on the bottom.
I've also seen enamel pots sold as 'frost resistant' which may or not hold up depending on temp conditions (I did find that these don't hold up to furniture movers...)

I had visited Denver Botanical Gardens one year and admired their outdoor planted containers. I was told the containers stayed outside year round so I asked where they purchased their 'frost resistant' containers. You could ask around your area too.
I have no experience with containers sold as 'frost proof'.

Well, with webesemps.

make sure it has good drainage, that might also help prevent some damage (from the moisture in soil expanding when frozen)

Thank you, Bev and Alex. I also read somewhere that it is good to choose a plant that can handle cold a couple of zones colder than your zone because, with the pot above ground, the soil will get colder.

lauriemorningglory said:Thank you, Bev and Alex. I also read somewhere that it is good to choose a plant that can handle cold a couple of zones colder than your zone because, with the pot above ground, the soil will get colder.

I second the "rated 2 zones colder". We have no problem keeping hardy stuff (zone 5, 6) in a pot year round. Plants rated for zone 8a/7b in the ground often fail in pots due to frozen roots during a cold (lol, for us) winter.

Saw some concrete large vase containers years ago rated for Maine winters from an artist in Maine.
One of their suggestions for care was to leave the container empty or completely filled to within an inch of the rim.

That advice definitely applies to some of our weaker ceramic pots here. As the potting soil in a 5 year old weaker ceramic container subsides, the container tends to spall just above the current soil line.

We are borderline "hardy tropicals" in zone 8a/7b. The length of dormancy is the main issue with some of the plants i shouldn't bother trying to grow here.

Looking at frost line maps, frozen root zones are a given for you, even in the ground? Not sure if the 2 zones hardier advice will be necessary?

Happy gardening