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Today I planted an apple tree grown on dwarfing rootstock (M27). The soil at my allotment is very heavy yellow clay. But it's on a decent slope.

I dug a hole the depth of the container in which it came. The bottom of the hole was practically hard clay, you could make sculpture out of it. Therefore I did the following:

Put in some big stones. Then compost, fish blood and bone and horticultural grit, all mixed together. Planted the tree and the stake.

I fear that the tree roots might get stuck in the clay "ball", and that the drainage might not be as good as needed.

Can someone give me any impressions about this, and in case it seems it's doomed to root rot, is there anything I could do to prevent it at this stage?

Below you see a picture, and I am in Bristol, UK.

enter image description here

  • A picture would help! and where in the world you are located – kevinsky Sep 23 '15 at 9:53
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Apple trees do well in clay. There are a few things you could do different next time:

  • do not put stones or other soil amendments in the bottom of the hole. If the planting hole has reached the clay sub soil or pan then plant it high or "proud" as described here.

The addition of organic matter provides little or no advantage to the planting hole in good soils

  • backfill with the soil dug from the hole
  • plant the tree so that the soil in the pot is level with the ground unless you are planting high due to clay
  • use two or three stakes as indicated here and remove them in one year http://www.ag.auburn.edu/
    From here
  • raise a lip or rim of soil around the edge of the hole to catch moisture
  • mulch heavily at the edge, thinning as you approach the trunk. Rake back in the fall if you get cool wet springs or mice
  • speaking of mice....put a tree guard around the trunk as high as the snow gets and a little more, they like to eat fruit tree bark if they hungry
  • decide whether your clay soil has a drainage problem. Is there open water in spring? Does it drain poorly after a heavy rain? You could put drainage pipe on the upper slope to dry out the soil

Edit: Now we have a picture I would recommend that you:

  • follow the staking practices in the picture. Use three stakes instead of one. - with the slope you have I doubt you will have wet soil in the spring
  • start planning now for the first year branch structure you want. From here:
    • prune during dormant season between November and early March
    • Cut back the central stem just above a wide-angled, strong shoot, approximately 75cm (2½ft) from the ground, ensuring there are three to four evenly-spaced shoots below
    • Shorten these branches by half to two-thirds, cutting just above an outward-facing bud
    • Remove any remaining lower branches

Ecnerwal's answer has inspired me to expand on what planting a dwarf root stock implies. From here which is written for North America but has some applicability:

  • Dwarfing root stocks have a limited root volume and benefit from supplemental irrigation in dry seasons and in droughty soils.(not the case for clay!)
  • Dwarfing root stocks also benefit from total tree support for the life of the orchard.
  • it does not produce root suckers or burr-knots
    • make sure ... that the graft union remains 2 to 3 inches (5cm - 8cm) above the permanent soil level. If soil is piled up over the graft union, scion rooting may occur and the dwarfing effect will be lost. From here

Lastly, apples need one or more pollination partners to ensure good fruit set. Types and varieties are not interchangeable but having other apple trees nearby of the correct type is almost mandatory.

  • Thanks a lot, kevinsky. Do you reckon the tree will do fine anyway? – usumdelphini Sep 23 '15 at 8:31
  • Great answer Kevinsky! Just make sure the stem/trunk of this tree is not covered by soil, rocks, mulch. There is a point where roots grow and then there is the trunk. Make SURE that trunk's bark will not be compromised by anything that will allow moisture to encourage bacteria that will girdle your tree. – stormy Sep 24 '15 at 23:18
  • But with a tree so small/new staking IS NOT IMPORTANT. And it inhibits the growth of supporting roots and a thick strong trunk. Trees NEED movement to facilitate getting bigger, stonger and able to resist winds. Trees will grow nice and straight all by themselves!! – stormy Sep 24 '15 at 23:20
  • argghhh...also this tree was grown in clay and to be planted in clay is PERFECT. A sandy/loamy soil would direct water away from the rootball and easily starve a tree of water. Did you see encircling roots? Did you break up the outside of the ball a bit to encourage new roots and stop the encircling? Take the stake OFF. There is no way a wind will blow this guy over and now is good to establish roots/growth. – stormy Sep 24 '15 at 23:24
  • @kevinsky About the pruning: the tree is already 2-year old, according to the nursery where I got it. How does that affect your pruning instructions? Thanks in advance! – usumdelphini Sep 25 '15 at 16:46
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IME, IMHO, etc...but I'm normally also dealing with bare-root trees, not potted.

Best bet with heavy clay (or most soils) is to not, in any way, improve the soil in the hole. While counterintuitive at first, all that does is to encourage the tree roots to stay put in the hole. If the tree is simply planted in the soil that there is, the roots have no reason to prefer the "improved hole soil" and will develop normally, putting up with (and growing through) the soil that there is.

What you can do (but not late in the season) is to apply compost or a mulch that breaks down easily from ~6" away from the trunk out to, or a little past the dripline (area of soil under branches) to feed the roots and encourage worms which will improve the soil in a manner that is not detrimentally confined to a dug hole. Growing things like annual alfalfa (but that's hard on clay due to pH), daikon radish or other cover crops with major root activity is another approach.

With M27 being an "ultra dwarf" and somewhat brittle rootstock, permanent staking is recommended (sorry @stormy, but some highly bred dwarf trees just don't grow strong if grown free - they grow for a while and break when the wind blows.) In larger installations (orchards) a heavy wire fence serves to stake a whole row of trees. In a single-tree install, you'll need 1-3 stakes that will hopefully last the life of the tree to keep it intact.

  • Source favoring staking M27 Dwarf rootstock trees: orangepippintrees.co.uk/articles/… Having seen some of these grown in commercial settings, I can't agree more. They get your fruit tree producing fast, but they were never bred to stand by themselves. – GardenerJ Sep 25 '15 at 17:26
  • Yeah absolutely always stake M27 - (personal experience) – J. Musser Sep 25 '15 at 17:50
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There is no easy answer here, firstly I would question why in the location shown in your picture have you chosen such a dwarfing rootstock? This tree may not flourish here. Firstly I would dig up,the tree and remove the stones as they will just make things worse. Clay is impervious to water so the hole you have dug will just fill up with water from the slope. Consider if you just dug a hole here it would fill up with water as you have created a sump. Digging a bigger hole and incorporating a lot of organic matter may help but you still have a potential hole full of water. My advice would be to plant in as small a hole as possible without improving the soil as already advised above and try to engineer the surrounding surface soil to divert water away, sealing the hole with clay soil but not covering the graft, the tighter the fit the less standing water will enter the planting hole. If the tree gets established It would do quite well. As advised keep it well supported all its life and good luck.

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    Planting high is the best solution to clay soil, more so than adding organic matter or stones. Apples can do quite well in clay if given time to root properly – kevinsky Dec 8 '15 at 18:24
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Eek ! If this were my tree I'd carefully remove the whole bolus of the tree from the ground now, as carefully as possible, in order to save it from the dreaded root rot.

You are absolutely right to be concerned about the drainage issue, even though there is a slight slope. I've lost trees on a slight slope but they never had sculpting-style clay close to the rootball. In other words, my trees had a healthier prognosis but died of wet feet in a long wet spell anyway.

Please, as tree-lover I say, gently remove that lovely tree and put it where the roots are cool and moist while you go to work to dig a much deeper and wider hole for it. Then put layers of organic material and the original (not sculpting-clay though) soil back in the hole. Gently replace the tree, asap, in a 'cup' in this larger planting hole. BUILDING THE SOIL SURFACE UP TO A GOOD ONE FOOT ABOVE the surrounding soil BEFORE replanting the tree. Firm the area down a little, then, stake firmly, (3 stakes), and always keep a mulch on the roots.

If the tree shows signs of wet feet (drooping, yellowing, water sitting around it) either dig a runaway down the slope, and/or dig the whole tree up and out of there to save it's life. Then, replace it in a day or two but sitting even higher than it was before. You will always have to keep an eye out on how its doing, in order to prevent death by wet feet. Location, location, location ! All the best ! Voice of experience (with fruit trees growing in clayey soil).

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