Potatoes.

Couple of points to consider, Paul

1. By the time you have paid for your compost you might not find growing potatoes in bags quite so economical.

2. You won't need rocks or gravel

3. You can plant them all at the same time: the ones that get left longer just give larger potatoes

4. Can you add your locality to your profile please so we can see roughly where you live. I plant potatoes out around mid March - as you can see I live in Reading - but those further north would leave it until later

5. Mostly it is wise to avoid supermarket potatoes to grow from, as they are not certified disease free. In tubs it could be OK but make sure you never put the spent compost on any potato or tomato plants in the future, just to be sure

6. The yield is dependent on variety and growing conditions. Mostly you would get 16-12 potatoes per tuber as an average

Hope that all helps

3 bins that size u cud plant 4 seed potatoes in each

12 potatoes could get u 100 odd spuds
Iv read some tips to plant 3 potatoes then add 6 inch soil then 2 more potatoes then more soil
Upto u but id say 3 to 4 per dustbin. 

Full sunlight
Great fun tho growing them and getting a good end result

this year I am only going to grow a few potatoes in the allotment, and more in containers.

it is true that by the time you buy the compost there is probably no financial gain, but come June when you are feeling into the compost and picking new pototoes off the root, cooking and eating 20 minutes later, i assure you this will not be a consideration(mouth watering just typing this

Thanks for all the info, all taken aboard