How deep for a raised bed?

[cadburyegg]

I'm getting quotes for a raised bed atm. Apparently sleepers are 20cm high so I would want two sleepers high for 40cm depth. I wonder if I should go up to 60cm depth or if it's not really worth it? The beds will be on clay soil, so drainage isn't too much of an issue. I want to grow a couple of roses, perennials, annuals rather than big trees or shrubs.

Hopefully this isn't a stupid question , I'm new to gardening! TIA

I think 40cm should be fine for what you describe. The only beds I've taken to 60cm were for growing long carrots!

Mine are only one floor plank high

Roses have a long taproot so I'd advise 40cm as a minimum. I'd be inclined to go deeper.

40 cm max needed normally in your case it depends what you want flower beds I would do 40-60 cm. Clay will water-log and clump so be careful. Depending on what you want you can put down cardboard and then new soil on top - 60 cm above ground means you won’t have to bend down too much if at all to weed, prune etc

Have you got a picture of where they are going? I can try to help?

My planters (with bases) are 40cm deep for bulbs and annuals. My raised beds (have roses, oriental poppies and loads of bulbs and perennials in) are 60cm deep. The roses have really long tap roots which go down through the clay under the raised bed!

I have raised beds that are 45cm deep (2 concrete blocks). They are good for protecting plants from frost, I’ve got lots of exotic plants that do well in them. Mine are fairly wide, and I’ve found it can be difficult to dig/weed/deadhead/prune/stake in a raised area. Something to consider as you plan yours.

Two planks worth, so around 50 cm.