Leylandii - in a raised bed - what do they like..

What the Royal Horticultural Society say about pruning, with the observation of having to check for birds' nests before pruning, and not pruning if nests are present. Note that it really requires multiple prunings during the growing season. It will not regenerate from old wood.
www.rhs.org.uk/.../pruning-guide

What some gardeners say on the Gardeners World blog
forum.gardenersworld.com/.../leylandii
With some alternate suggestions (species that will regenerate if hard-pruned to old wood)

The Wiki article is accurate IMO.
en.wikipedia.org/.../Leyland_cypress
Note the reference to 'shallow root system' (I'd not be sure about the raised bed).
And the 'legal aspects' w.r.t. Part VIII of the United Kingdom's Anti-Social Behaviour Act 2003
And its (as yet unknown) ultimate size. One of the original crosses is still alive and still growing at a height of forty metres.

My personal opinion is that you are really looking at a mature-ish hedge which has a depth of at least 4 feet (edge-to-edge), quite possibly more. Therefore a 2 foot raised bed is too little space IMO.

Your choice. Personally I wouldn't plant it in a garden unless it were a very large garden (landscape proportions).

Hi,

My thoughts are :-
1) Use raised beds for fruit, veg or other high priority plants, not leylandii. 
2) If you do want to keep your leylandii, don't expect anything to grow near them. Even grass can end up dying.
3) Leylandii are, as you probably already know, known for being fast growing and a really good screen. Therefore a good option, and birds can use it to nest in. But, because of the fast growth, it needs maintenance.
4) If it's intended for a boundary, and you have neighbours the other side of the referred to wall, make sure there's easy access for maintenance on their side, and they are happy about having leylandii there too.
5) Don't spend money on compost for leylandii. It doesn't need it. Tough as old boots. If moving during a Summer drought, might need to water occasionally. At other times, it's almost harder to kill than keep alive.

Personally, I would not plant Leylandii, especially in a 2' wide raised bed. Leylandii can easily grow up to between 20m and 25m (65'-80'). There are some in gardens a few houses from us. Enormous wide monsters, taller than mature oak trees. One was blown down in the recent storms, and made a huge mess.

Have you thought about other hedging trees that require far less work and are less thuggish. Beech makes a good, quick growing hedge. Easy to maintain, and their (dead) leaves stay on all winter. Holly makes a good, evergreen hedge, easy to control, and good for wildlife.

I was in the unfortunate position of having some 10 Leylandii forming a tall hedge at the back of a garden in a house I owned. They were pollarded to a height of 15' - note the garden was on a steep slope, with a retaining wall. Thus, the height of the wall plus the height of the neighbours' fence, meant the hedge was only about 3'-4' higher than the fence, which the neighbours' weren't fussed about as they were happy with the privacy it afforded them.

HOWEVER, to maintain the trees, and make sure the branches did not swamp my smallish garden by growing out sideways, I had to clip the hedge every year. Sometimes twice.

The problem is Leylandii will not grow back from mature wood. Therefore, you only have a short window in a year to clip the hedge branches back (say 2 to 6 inches) before you hit mature wood which has no greenery growing on it. At which point you will have brown patches, because the mature wood will not send out any shoots.

Oh, even pollarded, the Leylandii put up a valiant effort to grow side branches upwards at the top of the trees. I'm not sure if they would gain any substantial height if I left them grow, but I didn't take the chance, and hacked back branches attempting to grow upwards.

If you are dead set on growing Leylandii, then pretty much any sort of soil will do. Depends how deep your pockets are an how fast you want them to grow. Top soil is good enough You can chuck in compost if you want. Good watering and some plant food will get them romping along - but then you have the monster size to contend with, and the possibility of arguments and litigation with neighbours if they grow too tall.

There are other, more benign confers you can grow, which aren't as thuggish but have the advantage of growing back from mature wood therefore your clipping regime does not have to be so fraught. I don't know what they are, but a decent online search or chat with nursery will throw up options.

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