Pruning can be a pain point for many hobby gardeners, knowing when and how to prune your plants can mean the difference between leggy overgrown bushes and well sized plants that bloom prolifically. Here I will explore when to prune common landscape flowers like azaleas, lilacs, hydrangeas and butterfly bushes.
To start, determine when your plants bloom -- early spring blooming plants like lilacs, azaleas and rhododendrons all set buds during the previous summer or fall, meaning if you prune them in winter or fall you will be cutting off all your blooms. The best time to prune a lilac is right after it's flowered (usually late spring) and the same holds true for azaleas and rhodies -- however, you should keep in mind lilacs are not as tolerant of hard pruning as azaleas and rhododendrons, you can prune these nearly down to the ground and they will return, but a lilac should be pruned more conservatively if you wish for it to bloom for you the next season. Stick to a 1/3 pruning budget for lilacs, leaving about 2/3 of the plant intact. Concentrate on branches that cross or stick straight up in the air, and for azaleas or rhodies, you pretty much can't make a mistake, they are just too hardy to be deterred, so these can be great plants to practice your pruning skills on without dire consequences.
Plants that bloom in the summer like panicle hydrangeas or butterfly bushes, should be pruned in late winter or very early spring (February or March) because these plants flower on current season growth. Panicle hydrangeas such as Lime-light, or Bobo will benefit from removing any dead or diseased branches, and a clean up of weak or very thin stems. You will also want to cut back crossing branches, and cut back the total height of your plant by about 1/3 to 1/2, leaving room for new growth but making sure the plant wont outgrow its current space. When cutting you should always cut at an angle, ideally about 1/4" above a pair of buds or nodes. Butterfly bushes should also be pruned in early spring and hard pruning (down to about 12" from the ground) will force out lots of new stem growth and more blossoms. Avoid pruning either of these plants in late fall, you want to leave the old growth for winter protection.
If you have a pruning question that I haven't covered here, feel free to contact me. I have a few pruners that I prefer to use over others and those include the Felco F2, and any good carbon steel Japanese flower pruner such as this one (please note these are best for softer, less woody stems). I also recommend a sharpening tool for your pruners, they will need to be honed after each use and oiled every few weeks to stay in good shape.
