I found this post on garden forum and it is true, don't fall for winter warm spells:
A NOTE ON WINTER PRUNING:
"There has been some odd weather going on in the northeast. It's winter and temperatures have been in the 30 's one day and in the 60's the next. A note on trimming your shrubs...as I was doing yardwork outside today and was almost tempted to do some trimming- I DID NOT! There have been posts about trimming evergreens and when. Just a note-do not be fooled by these mild temperatures! Trimming evergreen shrubs at this time of year can spark new growth in the warmer temperatures and if there is a sudden freeze suddenly after that -it will not only cause winter burn on your shrubs but also put unnecessary stress on them. Better to resist the temptation and wait until Spring! Thought I'd share. Happy gardening! Happy New Year!
The best time for pruning shrubs(especially evergreens) in this region is early Spring (late March-April)."
Posts
