Have decided to try and do things properly this year so have started two dhalias (Manhattan Island) off in a deep tray, not having a greenhouse they are on the windowsill in the kitchen. Both are beginning to sprout, but how big do the new shoots have to be before they are put into the pots in the garden? Does it depend on the weather, does it have to be warm before they go out? Any help would be apprecialted. Space on the windowsill is limited as I have seeds growing too.