Which is more important for leeks/carrots at this time of year, heat or light?
I have 2 growing beds converted to large cold frames (1m x 2m) using polycarbonate green house panels for sides/lids. These increase warmth but decrease light. I remove the lids from May onwards to avoid overheating/drying out. I'm growing leeks and carrots at present, carrots sown/leeks replanted late June/end July. With daytime temperatures now dipping here to 10-15 deg C (Scottish Highlands), should I now put the lids back on? Which is more important for the plants at this stage, heat or light?