I have recently sown some Greyhound cabbage seeds in single modules of a polystyrene tray which I placed on a heated tray. I used multi-purpose compost.
The idea was to have small plants which could be potted on individually rather than the random, overcrowded nature of my normal seed sowing!
80% of the seeds are now up and, despite removing the tray from the heat (its now just on an indoor shelf near the window in the house), the stems are an average of 2" long before the first pair of seed leaves. These leggy plants are what I am trying to avoid.
The stems of tomato seeds I planted are also around 1" before the seed leaves.
What am I doing wrong?