Recognise when young plants are ready to move and reduce transplant stress with a few simple steps.
Transplanting is a shock. The point is not to avoid it — it is to do it gently, at the right time.
The right time
Second set of true leaves, roots beginning to circle the bottom, and the weather looking kind for the next three days.
Water before, water after
Water the seedling thoroughly an hour before you move it, and water the new hole right after planting.
Handle by the leaves, never the stem
The stem is the whole plant. Leaves can regrow. Pinch the second leaf between two fingers and pull.
Give them shade for a day
An hour of direct sun right after transplant can kill a seedling faster than anything. A simple cloche or upturned pot left on for a day gives them time to settle.