Raised Bed Advice

[Ibroxblue]

Hi All,

I am going to make some raised beds (out of gravel board) initially for carrots and parsnips so that I can make the conditions (I have heavy clay soil) more suited to them.

Can I please ask without spending a fortune what I should mix in (sand / compost / topsoil etc), in what quantities and how deep the bed should be? Should I also add chicken pellets etc?

I am also going to put a polythene screen around the bed to stop carrot fly but how high should this be.

Thanks for everyones help in advance.

[SarzWix]

The sand/compost/topsoil proportions is something everyone asks, but no-one seems to know the definitive answer
When I filled my carrot bed, I used 3 x 70l compost, 3 bags of topsoil and a small bag of sand. The consistency seemed just right, and the carrots loved it, no added fertiliser

[Snadger]

The polythene surround needs to be about 30 ft high as the carrot fly aparrently nest in trees!

John Innes No 3, which is basically what you are trying to achieve is 7 of soil, 2 of sand and 3 of peat/coir/compost for water retention!

Bed covered in Enviromesh is the only way I can grow carrots!

[taff]

The bed should be as deep as you want the roots to grow, so at least 6" but better off with 8" - 12"
Carrots and parsnips don't like [apparently] heavily manured or stony soil, so something that's free draining, not stony, and not recently manured should be fine.
Not helpful for right now but if you're building any for next year, strip the top of the grass off - if you're making them on lawn - stick it upside down somewhere out of the way, cover it in black plastic and it will rot down, and you can use that in another bed next year, I found mine was still quite rooty, but after getting the largest bits out, the soil is fantastic for root veg, very light and good for roots.