I have a question about my butterfly bush. I have read not to prune it back until early spring, and then again I hear to prune it to the ground in the winter. What is the best approach? Also do Butterfly bushes need to be pruned every year and is it too late? We pruned our bushes last year and they were beautiful but took forever to get tall again. I would like them to fill an area in our yard and would like to know the best way to care for them.
Regarding your butterfly bush (Buddlia), you are safe to prune it at either time as long as it is late winter moving into early spring. Avoid pruning though in early winter. The reason being, the stems are hollow and any water that accumulates in the stem and subsequently freezes will cause the wood to split. That’s not a good thing. Butterfly bush bloom on new wood so as long as you have plenty of sunlight, you’ll get lots of blooms throughout the summer by pruning in the spring.
Butterfly bushes do not need to be pruned every year. In fact, you only need to prune them when they get too large for the space allotted. But since butterfly bushes only bloom on new growth many gardeners prune them severely each spring to encourage lots of new growth and lots of flowers.
You can prune this shrub back to twelve or twenty-four inches high. For most plants, that’s a drastic reduction. But these plants can not only take it, they’re often better off for it. This way, you retain some of the growth from last year which will fill in that area of your yard more quickly and provide you with plenty of flowers. Remove the spent blooms periodically during the summer to encourage additional new growth and subsequent flowers until frost.
If they have already started to leaf out, you can still prune them back some, but if you prune below new shoots, it will take much longer for it to fill out this year. A fertilizer application in March or April and again in June or July will help to encourage growth. I suggest a generous helping of compost or all-purpose organic fertilizer. If you’re inclined to use synthetic products, a tablespoon of 10-10-10 for each foot of height is appropriate. Sprinkle it around the shrub out to the drip line, but no more.