[A Reyt Tayty]

Is an 8" raised bed deep enough for sprouts? If not, what would be suitable?

[Yorkie]

I would worry that it isn't deep enough for the plant to be firmly anchored in windy conditions - which can mean that the sprouts 'blow' rather than keep tightly shut.

I'm not sure about minimum depth though.

[viettaclark]

I've got 18" raised beds on earth and although I'm only trying sprouts for the first time this year I've grown other tall crops such as psb. The main roots do go down about 6-8" but the feeder roots go down much further as raised beds tend to dry out quicker.
You could be alright if your soil is heavy to help anchor the plants.
What are your beds on? Earth would be ok.

[A Reyt Tayty]

Thanks lads. I'll stick to something a bit lower to the ground I think.

[arugula]

Or ladies.

[A Reyt Tayty]

Or ladies.

Indeed. 

[sunshineband]

As vietta said, if your beds are on earth than there should be no problem.

I have PSB that is well over a metre tall growing still, and our beds are only six inches deep...... plus the soil where they are built 

Sprouts were fine too... they are finished now though 

[A Reyt Tayty]

As vietta said, if your beds are on earth than there should be no problem.

I have PSB that is well over a metre tall growing still, and our beds are only six inches deep...... plus the soil where they are built 

Sprouts were fine too... they are finished now though 

It's actually 9 1/2" deep: that extra inch and a half could make all the difference!

I was intending just putting it on a piece of lawned ground with some weed fabric in the bottom. That should give good drainage, and I would have thought the tap root would get through it ok. Perhaps best to remove the turf? My original intention was to use it for onions next year, but I hate to see it go to waste when I can bang something in it this year.