1. Yes, apples require four seasons and will not do well if kept warm all the time. In Zone 7 you will not risk freezing out the roots even with a container grown plant.

2. Much depends on the rootstock, but you can probably do OK with the larger pot size as long as you don't overwater and have a reasonably moisture-tolerant rootstock.

3. I am not an expert on potted trees but would think that with a 20 gallon pot you could grow a fully dwarf apple tree for many years without having to root prune.

Get something on M.27, EMLA.27, P.2, P.22, or Geneva 65 roots and it will do fine. It may take some searching to find a place that has these. If you know how to graft apples yourself you can just get rootstocks and graft your favorite apple on top, which might be easier.

frozen_north,

Thanks for the information. I was not aware I could graft my own top onto a root stock. I am now going to research how this is done and try with a neighborhood Seckel pear that is very prolific and healthy but is about 25 feet tall!! I do not know of another pear tree within 1-2 miles but this tree is loaded every year. I will try to get the cutting before the new home owner cuts the tree down.

You have given me information on what could be a dangerous new hobby!! Yikes :-))

DL

Hi dancinglemons-
There are quite a few decent videos on YouTube that show how to graft apple trees. You might want to take a look there. -Glenn

You don't need an exotic, super dwarf rootstock to grow apples in a pot. M9 or M26 are readily available and will work fine as to tree size. In fact I'd rather have the extra vigor. Just the low soil volume in a pot causes all the vigor reduction needed.

The Fruitnut

Pears tend to be more vigorous and have fewer options available for dwarfing rootstock. In your zone there are some roots that will limit a pear tree to 15-20' or so which is better than anything that will grow here.

I'd suggest starting with an apple.

I'll defer to fruitnut on the dwarfing effects of containers. I've only ever tried to grow citrus in containers and it was a failure.