Jumbo seedlings should be potted up and grown on for a few weeks in a frost-free spot - an unheated greenhouse or bright windowsill would be ideal. Larger, pot-grown plants can be planted straight out providing the soil or compost is neither waterlogged or frozen.Keep well watered, and feed with a good, high potash fertiliser (such as Tomorite) on a regular basis. Pinching off the spent flowers will encourage more to form. Protect young plants from slug damage using environmentally friendly slug pellets or beer traps.