|Last fall I purchased 4 Knock Out shrub rose trees from my local nursery. I over-wintered them in the house and am needing to know when to prune them back and by how much. I also need to know when I should start fertilizing them. Please help!|
|Required pruning is absolutely minimal: in the spring, trim out any winter damaged canes. During the season, should a particular cane grow out of bounds a bit, just trim it back for neatness.|
If desired, pruning can be more intensive. Early each spring simply trim the entire plant back very short to encourage dense new growth -- you could use a hedge shear to do this very fast. Alternatively, each spring or maybe every other year you could trim out some of the oldest canes by cutting them at the base. It takes some time and you need to use a good sharp bypass hand pruner to do it this way.
Either method will help keep vigorous new growth coming in and keep air flow moving through the center of the plant a bit better. You will also be able to keep the plant tidy although their normal shapes are fairly regular regardless.
Fertilize after pruning or just before new growth starts to push out. Enjoy your roses!