1. Maybe 6'.
2. No and NO! Step-overs are grown on DWARF (not semidwarf or full-size) rootstock.
3. How high can you step?

Maybe I'm wrong, but your questions make me think you haven't really researched this topic at all. Before you go buy some trees, I'd plan to learn quite a bit more, and I'd do some consideration as to why I wanted to use this method and what the potential down-sides (there are some) would mean in your application.

You need a very dwarfing root stock and you need to start with a maiden whip. I don't think you'd have much luck trying to make an established tree into a step over.

Here is a link that might be useful: How to train step over apples

Have you tried researching this online? If you Google "step over apple trees", you will generate quite a lot of how-to information, including photos of established step over plantings. They are essentially a single tiered, horizontal cordoned espalier. Not terrifically dissimilar to growing fruit trees in a standard espalier format except that you start with very small trees - whips - initially.

Here is a link that might be useful: step over fruit trees

there is a fruit forum.. and i have never seen most of those experts EVER over here..

otherwise i dont care where you post

ken

I'd never heard of a stepover tree although I've made my living for the last 25 years entirely installing and managing fruit trees and running my fruit tree nursery. Add another 18 years and it's my total experience managing apple trees in a wide variety of climates and soils.

Brandon gave good advice but I would add that having a fruit tree so close to the ground has so many disadvantages for trying to get fruit production it seems more for novelty than anything else.

Here's a few that come to mind- being closer to the ground is huge encouragment to fungus problems- mice and other rodents would consider these apples their personal banquet, greater susceptabilty to mechanical damage, and more difficult to pick fruit (except for before mentioned rodents).

The only advantage I can think of would be if you were in Z3 or colder and wanted to cover the trees over winter. As far as saving space, wouldn't a fully dwarf tree trained vertically and only taking 4' of horizontal space save more room?- unless someone owns all your sky space over 12".

harvestman - they are typically used over here as an edging between vegetable gardens and paths. They do not cast shade on the veggies, take up no width to speak of and you can get at the beds to work by literally stepping over them. They are a pretty and productive way of growing fruit in the very small spaces most of us have to garden in. If you have plenty of space, are growing fruit only and are not concerned with veggies obviously normal cordons would be more productive.

Here is a link that might be useful: Step over as path edging

Thanks Flora, that makes sense. I don't know how the apples would do in our warmer and humid climate in the eastern U.S. but in the west it might work if the apples didn't scorch.