Thinning the Seedlings
If seedlings are allowed to grow too closely together, they will begin to compete for moisture, nutrients and sunlight. Thinning prevents overcrowding and provides a better environment for the remaining seedlings by giving them the proper space for good growth and development. Thinning also reduces the risk of disease by providing better air circulation around the plants.
To maximise crop yields, it is best to thin seedlings in stages, rather than all at once, to allow for any losses due to pests and diseases. Start thinning when the plants have one or two pairs of true leaves; you should aim to leave seedlings with a finger's width distance between each one.
Always make sure that thinnings are tidied away, as their scent may attract pests.
Small seedlings can be thinned by nipping them out at ground level; this will reduce the amount of root disturbance to adjacent plants. Larger seedlings should be lifted carefully out of the soil, retaining as much soil around their roots as possible. Spindly, weak seedlings should be discarded, whilst strong plants may be replanted elsewhere. Continue thinning as the seedlings grow until they have reached the spacing required for mature plants.
