But I had grown my 15 year old tree in pots until it was 13 years old. After making sure it was firmly established in a good pot, it stayed outdoors at all times except one or two storms with extreme wind. I plan on doing the same with this new tree, and 50 smaller seedlings that will be arriving in the next few days.
In the first two photos below, you can see how a larger seedling is shipped from the grower. The roots are damp and wrapped in plastic, the top of the tree is bent over to shorten the length, the tree is wrapped in plastic and then newspaper, and then put in a plastic bag. That's it, and thankfully I have had warmer weather than normally, so the tree has not been exposed to freezing while making it from Georgia to Cape Cod.
In the photo below, if you look closely at the group of needles, you can see white aphids. Not too many of them, but I will have to either remove them by hand, or otherwise get them off of the tree.
The pot I am planting this is is a one-gallon container, about 12 inches tall and 10 inches wide at the top. I will fill it with some sandy soil about 4 inches from the bottom before placing the roots
After getting the tree set in straight, and the roots placed with plenty of room, I fill the rest of the container with sandy soil and place small rocks on the top of the soil to prevent soil loss during rain.
The seedling then gets a brief shower in the tub (will help to remove aphids), and then the pot is placed up to its rim in tepid water until all soil is moistened. Then, I will make sure it drains well before starting to acclimate it to the outdoors here. Next week is supposed to get cold, so the tree may stay overnight(s) in an unheated room, then back outside for the day.
Below is my new White pine after planting. I have been keeping it indoors in the shower (with the bathroom window open) at night, and putting it outside in this sheltered area during the day. Additionally, I put its pot in a 5-gallon pot and wrapped the smaller inner pot with plastic bags and old rags, insulating the roots.
And here it is in front of my 15-year old White pine, for a photo op!
When you get the chance, please plant a tree!