Dwarf trees need to permanently staked. We lost one because of straight line winds here in STL. Semi-dwarf can be pruned to be keep dwarf sized. That is what I'm going to do. An all around apple is Jonathan. I like them half red & green to get a crisp sweet tart flavor. As they get all red, they are all sweet. Jonathans get cedar apple rust, so spray them three times in spring with Immunox for CAR beside the regular fruit tree spraying.

I hadn't thought of planting semi-dwarf and trimming them back to dwarf size (about 6-10 feet high?). If I do that, how far apart should I plant? 12 feet?

Also, is it okay to plant in the fall? I am at the border of zones 5 & 6.

bookjunky, you can keep any fruit tree, standard, semi-dwarf, dwarf whatever size you want by pruning. Even citrus trees. If you go to Dave Wilson Nursery's web site, you can see how to prune trees to keep them "pickable". DWN also has some great You Tube videos on how to do this:

Dave Wilson Nursery You Tube Channel

Although spring is probably preferable in your area, I have planted trees and shrubs in the fall when I lived in N. Indiana. As long as you make sure you take very good care of them and help them establish their roots, and with a little mulching, they should make it through the winter. I would talk with your local orchard or farm supply, or your highest quality garden center about how to plant fruit trees in the fall correctly. You can also check your local county extension office, land grant college (U of Ill for you) & Master Gardeners for how to properly plant and care for fruit trees in the fall. I've included a link for you from the U. of Ill Coop Extension about growing fruit trees in Illinois. Think they have a pretty good web site. If you need more info, check out Purdue Coop Extension's web site, as I know it is full of good info, as I because a MG in Indiana.

Patty S.

Here is a link that might be useful: U of Illinois Extension: Small Fruit Crops for the Backyard

It might be a good time to see how the local orchards set up the trees. The Jonathans are in now. Take your tape measure with you.

I'd plant the trees in the spring. But that is me.

Here is a link that might be useful: Apple Journal - Illinios Orchard

By all means, I'd recommend selecting a rootstock that will anchor and perform in your native soil and environment. As previously stated, true 'dwarf' rootstocks will require staking or trellising, and can never be allowed to 'dry out' or they are 'toast'(they are dwarfed, to a significant extent, by the fact that they have a very weak root system).

Ultimately YOU are in charge of how large they become - if the tag says "Semi-dwarf, 12-18 ft" - or even "8-12ft", it's not going to magically just stop growing once it reaches that height.
And besides, how many people really think about how big an 18 ft-tall apple tree would be? That's essentially as tall as the second story of a house.
Like Ed Laivo at Dave Wilson used to say - about 'standard' apple trees - the tag should read, "May grow as large as an apartment complex, please purchase additional acreage to accomodate."
Prune, prune, prune.