godan verb (-ku), transitive verb
thin out; cull
Specifically used for thinning out plants, especially seedlings, to give the remaining ones space to grow. A specialized agricultural/gardening term.
大根の芽を疎抜いて、間隔をあけた。
I thinned out the radish sprouts to give them more space.
苗床が混みすぎて
The seedbed is too crowded, so we need to thin it out a bit.