Planting apple trees in a raised bed?

[Rabidbun]

Hi all! Got a quick question about tree planting as I'm doing the prep today for when they arrive this week and ideally don't want to kill em if I can help it! Done a fair bit of reading to try and work out what would work, but wanted to check it with experts before jamming the poor things into my garden.

The trees are an M9 rootstock and are apple trees. They are being planted in effectively an open bottomed raised bed (around a foot tall) which will be stood on a heavy clay soil. What I was planning to do was fill the bed with a mix of topsoil and shop bought compost and stamp it down a bit to reduce the level dropping over time as much as possible, before digging the hole to plant in.

What I am unsure on, however, is whether putting a layer of topsoil and sand on top of the clay first will be helpful, or whether to add some well rotted manure right into the bottom as well in the hope that the worms will mix the clay, sand, topsoil and manure in a bit before the tree roots get there, thus helping it root deeper? The bed is a wide one, so there is a risk, as I understand it, that if I cannot encourage the roots to go into the clay then the trees will become shallow rooted? I am not able to dig much at the moment either, so digging a lot in the clay below the bed isn't a massive option.

I'm also planning to be good and pull off all the fruit that sets and plant chives and nasturtiums around them to help with bugs.

[FB.]

You'll probably be OK just to mix your ingredients into the raised bed and compact it down a bit (and later throw on some more soil/compost to build the level back up as it settles.
Clay is very moisture-retentive, so the roots will probably grow down into it in search of water. Rainfall from above will also wash nutrients down into the clay, where the roots will chase it.

M9 is not a strong rootstock though (about 6ft height/spread in 10years if unpruned in average soil - perhaps 7-8ft in good soil), so it is wise to keep them well-fed and well-watered for the first couple of years - and avoid fruiting for a couple of years because M9 is known to put all its effort into fruit to the point of killing itself in the process.
M9 also has small and brittle roots, so a heavy fruit load on a young tree or in windy conditions can literally snap the tree off at ground level.
Besides: allowing a young tree to fruit often ends up with pests (insects, birds) getting what few fruits there are. Fruits on young trees are often small, poorly flavoured and don't keep well.
It is better to direct the young trees energy towards growth until it can produce such a heavy crop that insect and bird losses will still leave plenty of fruits for you.

On the plus side, once mature, M9 produces good crops of well-sized and well-coloured fruits (better quality than most other apple rootstocks).
The fruits on an M9 tree often ripen slightly earlier than when grown on other rootstocks.

M9 is also quite tolerant of wet and heavy soils.

..........

Which varieties did you choose?
Variety can make quite a difference on how the trees perform, or how fast or slowly they grow.

[Rabidbun]

Thanks, have done just that in prep for the trees arriving this week! Very much appreciate all the info - amazing how much there is to find out about each fruit now I am starting to grow it seriously (given my last attempts were just bunging random berry bushes into pots and hoping for the best)!

It's going up against a trellis, so will be able to tie it in very securely to the fence posts that hold the trellis up. Didn't dare go for a huge tree incase it got, well, huge - I've only a small garden as the previous owners sold off the back of it to let a bungalow be built (along with an apple tree) alas.

The two types I chose were Sunset and Worcester Pearmain, both 1 year old. Just hope they taste nice after the two years!

[FB.]

I would suggest a light prune of the tips of the branches when they arrive - just clip off the top bud or two.
Rather than let them put energy into flowers, I'd suggest "nipping them in the bud". The flower buds are the first to open and are usually large, protruding and slightly furry.
If you pinch the flower buds out before they open fully (literally pinch out the bud with fingernails - don't clip off the whole side spur; just the bud at the end), a short side branch often grows in the buds place.

Don't worry about losing flower buds on an M9 tree; there will be plenty more appear in future. If the tree gets too vigorous (unlikely with M9; the problem is usually with keeping up the vigour), you can always prune the new growth back to 2-3 buds in July, which will stop growth and create fruit buds for the following season.

Your Worcester Pearmain will bear a substantial amount of fruit on the tips of branches ("partial tip bearer" **). Fruit buds form in August-September. Winter pruning will therefore prune off much of Worcester's next crop. Bear that in mind when the trees approach their desired size.

**
Many people fret about part tip bearers and the slightly changed pruning needs, but ptb's can be left unpruned and still produce a good crop, since it tends to be younger (healthier) wood which produces the fruit.
Part-tip bearers also make more attractive blossom displays and more attractive trees.

I am a fan of ptb's for the more attractive appearance and lower maintenance.

However, vigorous ptb's (or pure tip-bearers) are too vigorous for growing as trained forms. Bramley and Blenheim Orange are good examples.
Worcester Pearmain is not over-vigorous. Worcester will try to grow in quite an upright manner, so bear this in mind when pruning to train it.

[Rabidbun]

Thank-you again, have printed this out and will pop it in my plant care file.