Move outside after frost danger over.

Expose it to outdoor conditions gradually over at least a week to harden it before leaving it outside permanently. Start with placing your peony outside for a couple of hours. Gradually lengthen the hardening off time. Moving it suddenly from a stable indoor environment to the one with changing temperatures, unprotected from wind, and sun operating much stronger than inside is not a god idea. Btw, it looks like a High Noon.

From the shape of the leaves I think it is a seedling of High Noon. They may be wider than normal because of being in a pot. When the leaves emerged did they have a bronze edge to them? If you can not remember watch it as it goes dormant. If High Noon it should develop the bronze edge if your season is long enough.

That pot is way too small.

Malfleur,

The pot is 14" x 14" x 18". I wasn't really expecting it to survive wintering in the garage. We had temps of -35C a couple of weeks this winter. So it is a nice surprise. I can plant it in the ground this fall, but I don't know if it will survive the cold weather.

Is 4a your USDA zone?

Yes. I'm in southern Alberta and it's 4a. I'm trying to determine where best to plant it as our Chinook winds are brutal to the plants. We can have -30C in the middle of winter and the next day be +10C and then drop below -10C a few days later.

Just this winter, we had several weeks of spring weather and then a big temp drop and snow for several weeks. Some of my neighbors' buds have already died because of this.

Your plant is hardy in zone 4 so should be able to withstand temperatures as low as -35 degree C. If it could take those sudden drastic changes is a different story. Did you buy it from a local garden center?

New shoot growth of tree peonies has often been said to be prone to spring frost damage, that will probably be the main issue for you.

Yes, i got it locally. I was told to not expect a bloom for at least a year or two.

There are several methods to reduce the change in temperatures directly surrounding plants from wrapping in various breathable materials, building a cage and filling it with things like leaves and straw, even if you have snow carefully putting a mound around it. One of the suggestions that is falling out of favor although I still recommend it is to place a barrier between the sun and the plant. In very cold temperatures the sun will heat the surface of the branches on the side facing the sun. If there is a sudden drop in temperature the sap that was drawn to the sunny side could freeze into ice crystals which could damage the inner bark. Too much damage and the sap will not be able to rise on that side of the branch. Planting in full sun can cause repeated freezing and thawing. One of the things I noticed when Hong was showing pictures was that in China tree peonies in nature were under shrubs. Several of my first tree peonies are planted on the north side of my house and for only a week in summer do they receive direct sunlight.

Our temperatures here are much different than when I started growing peonies in the early 1990s. At that time it was more common to have a week or more of below 0F. The change in temperature was more gradual. The past ten years what has happened was one day it is in the upper 60s/70sF then one night of below 0F. As a result there are more damaged or dying tree peonies in this area.

Thanks maifleur for the info. My house orientation is East West. Does it matter where I plant it as long as I protect it in a cage for the winter? Our winds usually come from the west.

Walk around your house and yard on a windy day where the wind is coming from the west. You may find that there are area that have less wind. You do not want a place that has no wind because it is best to have some air movement but you also do not want it in a place that because of landscaping or other factors the wind is higher. If you can remember where you had light snow the patterns of where it fell could help you. Bare ground probably a windy area. Drift's perhaps too little air. Let Mother Nature be your guide but no really low spots.

Since you got it locally it means it will do well in the famous S Alberta weather.

As the saying goes, If you don't like the S Alberta weather just wait one minute and it will change.

It could be very strange if they were selling plants not suitable for the local climate.