We prune shrubs for a number of reasons. We want to remove dead or diseased wood. We may feel the shape of the plant needs improving and choose to prune branches that cross or stick out. Another important reason to prune is to maintain or improve flower production. Timing is important with each of these, but particularly important to increase flowers. Often people get the urge to prune everything in the spring, not realizing that may be the worst time to prune flowering plants such as lilac, if you want to have flowers.
My friend Claudene asked me whether she could prune butterfly bush now. That’s a good question, because some plants bloom on current season’s growth and others bloom on last year’s growth. Butterfly bush is an example of the former and lilac is an example of the latter. If you prune these flowering plants at the wrong time, you will prune off all this year’s blooms.
Plants that develop flower buds on this year’s growth generally bloom in mid to late summer. For example, butterfly bush should be pruned as the overwintering buds begin to open in the spring, but after the danger of a hard frost is over. This will encourage the best flower production. Of course, predicting the weather is darn near impossible in Northern Nevada, so this can be a challenge.
Forsythia, the yellow shrub blooming everywhere right now, is a plant that blooms early on previous year’s wood. Mock orange blooms later than forsythia. It produces short laterals off last year’s growth and then flowers in early summer on the laterals. A good rule of thumb for mature flowering plants producing flowers on last year’s wood is to prune them within a week or two after flowering. Young plants that are growing and flowering well may not need pruning for a few years. However, the aging wood of mature shrubs produces few flowers and is a good candidate for removal.
Annual pruning is necessary only on a few plants. For many others, pruning can be avoided for a few years. In general, slower growing shrubs do not need much pruning at all.
Upcoming classes at Cooperative Extension, 6 to 8 p.m., 2621 Northgate, Suite 12, Carson City, tonight, “GMOs: Facts and Fallacies;” Thursday, “Composting and Vermicomposting;” April 14, “Weeds, Critters and Insects.. The fee is $5 per class. To sign up or to find out more, call 775-887-2252.
JoAnne Skelly is the Carson City/Storey County Extension educator for University of Nevada Cooperative Extension and may be reached at skellyj@unce.unr.edu or 887-2252.
