I have a number of Yuzu seedlings between 1 and 6cm high that have germinated from pips. They are in small plant cells in an un-heated greenhouse at latitude 50 degrees north here in the UK (outside temperature -6 celsius in winter and +27 celsius in summer). The greenhouse roof is old and light transmission poor; greenhouse temperature currently 11 to 13 celsius at night and up to 30 celsius on a sunny day. Most seedlings are green and healthy but one or two are pale yellow (!) and a couple seemed to shrivel and die as soon as they emerged.

My question is: what next? Should I re-pot them and leave them in the greenhouse for a year or two, or plant them into soil outside? Or re-pot and leave outside in summer? Do they need feeding, or can I provide a mulch or other natural material that will feed them? Is light intensity and duration more important that heat, at this young stage?

Greetings to all - I have just joined this forum - and many thanks for any guidance offered.