bush out
To become voluminous ("bushy") in appearance. That plant bushed out so much this year that it blocked some of my flowers from the sun. My hair is so curly that it will just bush out if I cut it short.
bush out
[for a plant, bush, beard, head of hair] to develop many small branches or hairs. His beard bushed out and really needed trimming. I hope the hedge bushes out nicely this year.