Raised bed under tree canopy and against a fence

[FlyMeToDunoon]

I'm in the midst of trying to renovate this area. When I took over the garden 18months ago it housed an enormous tree of a camellia, thin sad peony, fuchsia, ajuga and black grass and a lot of oak seedlings. I moved the plants I wanted into the main garden where they have recovered beautifully and cut down the camellia as much as I could which has left two stumps of around 15cm diameter and height each.
The area gets sun early morning for an hour or so and from around 2pm until sunset.
I discovered that although the front of the bed is built from wonky brickwork the back was simply earth against the neighbours fence. So, I've just dug away a trench along the back in preparation for a retaining barrier to be installed.
Now here's the tricky stuff- I don't have the budget for anything long lasting and was planning on using pallet wood to build the back of the bed. I've read up a bit on best ways to make them longer lasting but have questions.

Should I line with plastic to shield the wood from the earth and to help retain moisture in the bed or will this just hold moisture against the pallet wood and rot it quicker? I could also dig out and line the base with plastic as the earth here is incredibly dry. Or just weed suppressing membrane which I have a ton of from initial clearing of the garden.
How near to the fence should I make the back of the raised bed? Leave a gap of an inch or two, back it straight onto fence or leave a gap of several inches?
I don't think I'll be able to dig out the stumps, is it ok to leave them?
Planting is planned to be grasses, tallish daisies and something hardy and drought tolerant to edge-maybe pachysandra or liriope. Then a heavy mulch to retain moisture and attempt to stop the acorns from taking hold.
Any advice gratefully received.

You could oil or wax the wood, then line it with plastic. Teak oil, Danish oil, or even sunflower oil heated up with some hard beeswax or candle wax melted in it. Apply several coats and let it dry in the dun between coats.

Interesting. I think I have some Ikea furniture oil somewhere........

Gap of an inch or two. Maybe enough room to get a hoe in to suppress weed and seedling growth.

I would put a plastic liner in - with holes on the bottom on any soil - against the pallet wood to extend the life of it.

If you leave the stumps in they may resprout. If your can dig them out you will never have a better time to do it with an empty bed. But you can l just leave them also, just manage any regrowth.

Are you also putting in any spring bulbs? I find tulips tolerate a dryish location and the yellow ones are much more likely to come back.

Had recently thought to plan bulbs into the scheme. Thanks for the tip.

Check the type of oil you use, as some are toxic and will leach into the soil.

We’ve had pressure treated, plastic lined wooden raised beds and after ten years they’re disintegrating to mulch. I’m slowly replacing them in brick at the front, and block at the back. Its a massive undertaking alone and not enough of a budget priority to hire someone.

Ours were sleepers and I’m sorry but I can’t see pallet wood lasting as long.

I’m not sure if we should have done more maintenance on the wood. Life got very very busy in those ten years.

We have a sleeper wall in our back garden which we have lined with a plastic membrane between it and the soil. Even if the small amount of moisture causes the pallets to get damp and rot I think it will still help it last longer than not putting anything there.

@Charrington this is one of my dilemmas. I do not have the finance for decent raised bed materials and am not skilled or strong enough to do a lot on my own. Digging it out is exhausting enough.
I have considered just removing the bed completely by knocking out the badly made brick front.
A raised bed is easier to keep moister and to improve the soil within it though.
🤔

I've done something similar - a raised bed with 3 retaining walls and the back against a fence. I lined the whole area including the fence side with thick plastic. The reason for the bed is that the whole area is heavily overhung with trees in an adjacent garden, so it was dry shade.

If I understand your set up correctly i would line the pallet wood - would this then be wedged up against the fence? What you don't want is a thing that could end up with water pooling next to the fence itself. You could try oiling the wood as well but I think lining will be the most effective.