Thapranksta: Your question is a bit difficult as most orchards do not plant all their apples on one rootstock. Often they use several different ones based on what was available when they bought the trees, what pruning/spacing system they wanted for that orchard block,ect. Sometimes hardiness is an issue. For example hardy standard rootstocks (antonovka, prunifola, ranetka ect) are necessary in super cold regions such as ND,SD, WY,MT ect. Most other areas abandoned standard rootstocks years ago as they grow too tall to easily prune/spray/pick. Easier with dwf or semi-dwarf rootstocks. Often spur-type or low vigor varieties (Jonathan) need to be on a less dwarfing rootstock or they runt out and never amount to anything. I hate the terms dwarf or semi-dwarf as too generic. Orchards years ago in WI where I live switched to using M7 as semi-dwarf and free-standing, however they pruduce tons of root suckers. Now the hot rootstocks are Bud 9 & Nick 29 but these trees must be staked for the life of the tree. M26 is still used (8'-12' tall trees) but more prone to fireblight and can tip in heavy clay soils. Every rootstock has advantages and disadvantages depending on climate, soil type, low density planting or high density planting (Tall spindle) ect. My 17 tree hobby orchard has apples on M7, MM111, and yes even 4 on a standard rootstock. I vase prune heavily on some for height control. Others seem jsut fine. My site is weird as very low nitrogen levels. I have to fertilize heavily on new trees and even lightly on old ones or the leaf color is poor. I find my apple trees do not grow as tall at my site as other sites I have grown at. Hence my need for more vigorous rootstocks. Nobody can make you a good suggestion unless we know what soil type you have, are you willing to stake each tree permanently or want free standing orchard ect. Can you provide more information? When you do purchase your trees, watch out! Many mail order and almost all retail outlets will either list them as dwf, semi-dwf or no listing at all. Always ask what rootstock they are on. Don't buy if they can't tell you. A Mcintosh on M26 will be quite shorter than one on MM111. You cannot properly space your trees if you have no idea what rootstock they are on. In fact, one mail order place I called had Cortland on two different rootstocks. After the trees were harvested, they are all mixed together since both rootstocks are "semi-dwarf". Big difference though when some were on M7 and others on Bud 118.

all that deep raw mineral soil will develop into good soil in a very short time, well short by tree time. A year with mulch and it will look like top soil and in 2 years, you will have the o, a, b, c soil horizons I outlined above. wet mud and all that aside, it's does not help to back fill with top soil and it does not help to top dress with top soil. since you have a sharp slope, probably the best thing you can do is grow a "green manure" crop like an annual grass mixed with clover or alfalfa for one year on the whole slope. use a light scattering of spoiled hay or commercial top dressing over the seeded area to help it hold and give it something to start with. That will help hold the slope and build the soil. You can rake what you cut or mow, around the tree for more mulch. You original question is how much top soil. Well, the preponderance of testimony here is ... that's a bad idea, which is why no one answered it directly. You will almost always wind up with more problems that you solve doing that. Rebuilding a good soil from the parent soil is the best way to go in almost every case. Also, the manor of planting on a slope that you mention, with the front that open, is not a stable planting for a tree on s slope. You should dig back into the slope making a flat terrace with a flat "cove" back into the hill. plant the tree so that the center of the tree at soil line is back in the cove and so that in a couple of years when the slope erodes back to the tree, the base of the tree will still be at soil line. Use the soil you cut for the "cove" on the down hill side but do not plant in that loose fill. Just let it add stability to the low side, but plant in soil that is a stable part of the hill still. Well, good luck with all this. hope we helped.

'Flying Dragon', which is the contorted form of Poncirus trifoliata, is the only dwarfing rootstock for citrus. It produces a smaller tree than normal. Other rootstocks may cause a bit of variation in how vigorously the tree grows, but there really is no such thing as a semi-dwarf. There is confusion over the term 'standard'. This can either mean it grows at the standard rate and to the normal size, or it can mean the tree has been grafted high up on a tall rootstock to produce a definite trunk with growth near the top. Nurseries then add to the confusion by describing a tree that has been grafted lower down as dwarf or semi-dwarf. All it really means is the tree will branch lower down, but not that it will grow more slowly or finally form a smaller tree. If you want a small tree and the rootstock is Flying Dragon, then buy it - ignore anything else on the label about dwarf or semi-dwarf.

Although small ones can be had cheaply if of any size when purchased the 'Conica' probably cost quite a bit more than a typical seedling might have. More will have been paid for the vegetatively propagated cultivar, so letting it revert to the typical growth would be throwing away the extra money spent to get the dwarf compact form. And it take years for such reversions to overwhelm and kill the original dwarf growth, an ugly effect prevailing until then. Japanese cherry trees grafted on sweet cherry and older hybrid rhododendrons grafted onto Rhododendron ponticum are frequently seen here with the rootstocks having been allowed to grow up through and surpass the fancier named varieties stuck upon them. Sometimes when these are asked about and it is advised that the rootstock sprouts be removed the reply is that they are going to keep them anyway. This seems like a pretty bad idea, especially considering how much grafted Japanese cherry trees cost (grafting of hybrid rhododendrons is no longer common). Sweet cherry is pretty much a weed species here, if someone set out to get an unselected seedling (or rootstock cultivar, if any are being used) of this they could get it a lot more cheaply than buying a grafted cherry tree.