Best time to pot on leggy cosmos

[Wr3ck]

When they have true leaves or before? Obviously if I wait they’ll be even leggier.

When they have true leaves. This usually coincides with the root system being developed enough to move on. You can always pinch out the tips when they have grown a few more pairs of leaves.

Wait until they look strong enough. At this stage you can always compensate for the legginess by transplanting the seedling quite deep in the new compost.