How And When Do We Thin Seedlings?

This can be an emotionally painful experience for some gardeners - pulling out some of the seedlings in order to allow enough space for others to grow.  After planting seeds and dutifully watering, watching, waiting and hoping over them and they finally sprout from the surface of the earth, it seems just so horrible to have to destroy any of them!  But it must be done in order to have a successful crop.
The best time to thin seedlings is right after germination so the new root systems won't have so much competition.  Some crops will need thinning several times.
The best way is to find out the spacing/thinning recommendations on the seed packets and pull out the seedlings in-between the recommended intervals.
You can use a measuring tape as a guide or you can eyeball it.  See the before and after photos below of radish seedlings.
Get it over with - the sooner, the better.

thinning radish seedlings - before 

thinning radish seedlings - after