Top soil for dwarf cordons

[BearGardener]

Hello all,

I've recently moved house and my wife would like to grow a 'fruiting hedge' made up of half a dozen or so apple tree cordons. I have my eye on some trees on M9 rootstocks for this purpose and would propose to plant them 2 feet or so apart.

I've been out to do some digging and I've got quite good loamy/sandy topsoil down to about a foot maybe a foot and a half, then it becomes orange and sandy.

Now I've been reading that apple trees need 3 foot of topsoil ideally. That seems a lot to me. I can't believe most people have that in their back gardens. My question is how much topsoil do dwarf apple trees grown as a cordon actually need? And any other tips on growing cordons closely.

Thanks in advance.

[FB.]

Most people don't have deep, fertile soil in their gardens. It takes many years of working the soil for it to get that deep. Soil levels in inhabited places tend to rise over the centuries (hence why Roman ruins are often buried).
Farmers often don't sell their best land readily, and builders often scrape away half the topsoil to facilitate the building work - and then their waste rubble gets buried in the garden soil.

I would prefer M26 as a rootstock because it is just vigorous enough to be able to fend for itself in average soils and/or grow with some grass/weed competition. M26 doesn't generally grow too quickly (although a very vigorous variety such as Bramley will override a semi-dwarf rootstock).
M9 and M27 usually need very good growing conditions and cannot compete against grass, weeds or any other nearby plants or wandering tree roots from big trees nearby.
However, M9 may be useful for very vigorous varieties if the more normal vigour varieties are on M26 - the different rootstocks balancing-out the scion vigour.

With such close planting, I would avoid vigorous varieties or those which are tip-bearers as the pruning needed to keep them in their space will simply invigorate the vigorous varieties and will remove the fruit buds from tip-bearers.

[BearGardener]

Cheers FB,

I'll have a look at Ken Muirs Minarettes which I think are on M26.

[boundtothesoil]

I don't think you need 3 feet of soil. A good source of 'definitive ' information regarding apple growing in the UK is Bulletin 207 'Apples' published by the Ministry of Agriculture Fisheries and Food. I believe that the 1972 edition was the last to be published. It covers all aspects of apple production and orchard layout etc -well worth buying on amazon or ebay. It supercedes Ministry guidance going back to the 1920s, based on all the government research and trials into fruit production inthe UK (sadly whittled away by cuts to almost insignificance since the early 1980s).

Anyway, to quote from page 15: "The soil should have a depth of at least 18 inches in which unrestricted rooting can occur. Compact layers in the surface or subsoil.... generally cause serious restriction of roots and drainage defects by preventing upward and downward movement of water".

It also lists the factors which are of most importance in assessing soils for their ability to provide good rooting conditions for apple trees as:-
(a) depth of soil and the presence of physical obstructions.
(b) drainage conditions
(c) soil texture and soil structure
(d) stability of soil structure (i.e. likelihood of compaction etc).
(e) organic matter content and its distribution in the soil.
(f) the pH and lime status of the soil.
(g) nutrient status,

Lastly, it contains the following sentence which, in my opinion, sums requirements up:
" Apples ,as other tree fruits, require an adequate depth of soil in good condition so that roots can develop freely and at all times have sufficient moisture, air and nutrients."

I've always believed that even if the depth of soil doesn't naturally meet the above condition, the gardener/grower can manage the supply of air, water and nutrients to compensate to a large degree for this.

[orangepippin]

18" of good quality topsoil is fine for apple trees on M9, and a 2ft spacing should also be OK with M9.

If your hedge is to be partially ornamental, i.e. look attractive as well as be productive, you might want to choose 3 trees of 2 varieties (3 x 2=6) or 2 trees of 3 varieties ... if planted with alternating varieties this will give a more pleasing and regular effect. If you really want to choose 6 different varieties (which will give you more varietal interest) then make allowance for the vigour of individual varieties, for example don't plant a Bramley beside a Cox as the Bramley will grow much larger.