raised beds on gravel/ hardcore?

[sheridand]

We have a 250 ft garden. I am hoping to fit 4 6 by 10 beds at the bottom of it. Thing is fully 2/3 of the garden is gravel with hardcore underneath. I want to get shot of it, but the less we have to move the better! I was hoping we could make raised beds on top of the gravel, if I loosen ti and add sand maybe? The beds are aiming to be 4 ft high. I will be filling them with Fenland soil from my local farmer. Please tell me I don't have to dig up ALL my hardcore!

[Green Aura]

The only problem I'd see with it is drainage. Depending what the hardcore is, how deep and how compacted it could hold water.

But there's no reason why you couldn't dig out just the area for the beds then you'd have ready made weed-free paths in between.

Just don't fill the beds too full. In our old house a landscaper made us some deep raised beds and put MOT(?) round them covered with white shingle. Unfortunately he filled the beds right to the top so even sticking a trowel in showered soil all over -> weeds, albeit very shallow-rooted growing out of the paths He was brilliant at all the hard landscaping but I don't think he was much of a gardener

[MKG]

Anything that deep would work perfectly well even if it was on top of tarmac or concrete. Just make sure that either the gravel/hardcore itself offers adequate drainage (chuck on a couple of bucketfuls of water and see how long it takes to disappear). If it's not so good, make sure that there are drainage holes in the sides of the bed a couple of inches above ground level.

Mike

[sheridand]

This has been helpful. I live in the Fens, so I have ditches to the north and south. Everything tends to drain pretty quickly. I had a storm the other night, and a flood pretty much went in a minute. Those Fens..... However, the hardcord has been put down with non-fen soil, so it is more clay like. Our gravel expanse drains less freely than out garden. I wonder, could I just dig post holes and fill with sand? Or would it really matter with deep raised beds anyway? Maybe if I left a floor of gravel?

[MKG]

I think leaving the gravel would be fine. Water will only build up in the bed if it can't get out of the bottom or sides. If it's sitting on gravel, I would have thought it would drain pretty efficiently even if it has then to run across clay.

Mike

[Thomzo]

Am I reading this right that the beds will be 4 feet high? How tall are you? Don't make them too high or you won't be able to reach the middle. Personally I'd have more, smaller and shallower beds. You want to be able to reach the middle of them without having to walk on them. Also, remember, that you'll have to lift up all the compost, water and tools onto the beds so you don't want to make it too difficult. You could have some at different heights. Deeper ones for root veg and, if you're planning to include them, fruit trees. Shallower, easier to manage ones, for everything else.

Good point about not filling them too deeply. You want to leave room at the top to mulch once plants have started to grow.

Zoe

[sheridand]

You're right, 4ft is daft, that's a typo! More like 2.5. I am only 5ft tall! I'd have needed a step ladder! And the snails would still go up 'em!