We planted these last year. We chitted them standing them in egg boxes on the spare room bedroom with the heating off with all the earlies. They behaved exactly the same. They all grew nice green shoots by March. We planted them on our allotment about mid March in a hole about 8 inches deep about 12 inches apart with a handful of rotted manure in the bottom.
The do take up quite a lot of room when they grow, the leaves tend to spread a lot.
Dug the whole lot up in October and have them stored in the garage in hessian sacks...we'll be eating them forever!