Q. I have an easement in the backyard where I cannot plant trees. I have decided to plant as much as possible in the space I have left which is about an area 10×10. I would like to plant fruit trees in a high density there and keep the trees small for easier picking.   Multiple trees in a single hole about 18 inches apart. This provides a sequential harvest of fruit from different varieties at different times of the year. A. I would really caution you on a high density mini orchard unless you are truly committed to it. It will take more time and effort and require gaining some extra knowledge if you commit to any intensive gardening technique. If you are willing to spend a bit more time and effort (not a lot but the extra time is critical) then give it a shot.             A 10×10 area is quite limiting but you could still probably get about 8 trees in there with a combination of multiple trees in a single hole and trellising them. You might consider planting fruit trees in a hedge with no space between the trees and letting them grow together. Apples trellised along a fence on trellis wires about one foot from the fence and shade cloth protecting it from direct sunlight from the south side of the fence.             I personally wouldn’t plant any trees closer than about six to eight feet apart for a hedge or trellis. If you use apples or pears try to make sure they are on dwarfing rootstocks such as M111 for apples and OHxF333 for European pears.             There really is no true dwarfing rootstocks for the stone fruits like peach, apricot or nectarine but the Citation rootstock may give you a little. These stone fruits are normally planted full size and kept small through aggressive winter and summer pruning.             Another possibility instead of a hedgerow is trellising and I prefer it over hedging for small spacing. Trellising costs more because you have to construct the trellis but gives you more control of the plant and helps you keep it smaller.