This week we’re pruning the shrubs in our demonstration gardens as the snow melts off but before leaves emerge (yes, we still have snow!).
Pruning maintains the health and vigor of plants by removing dead, diseased or injured material and allows control of the shape of the plant while promoting fruit and flower yield by concentrating the plant’s energy.
This Rubber Rabbitbrush (Ericameria nauseosus) needs a heavy annual pruning to keep it bushy and under control. It seems like the more I chop it back, the more vigorous it gets! Other species like this Wax Currant (Ribes cereum) and our Blue Rock Clematis (Clematis occidentalis) need more careful pruning.
We use very sharp, clean pruning shears on smaller plants and pruning saws on large trees. Our pruners have been sharpened and bleached in a 10% bleach solution. It’s important to maintain sanitation and avoid transporting bacteria or viruses on shears.
We prune using the concept of ‘apical dominance’ which means that the plant has a propensity to have one main leader with all the other branches lower than the ‘main’ branch. Cuts are made just above buds that are pointed in the direction we want the branch to take. Our goal is to keep plants appropriately shaped (each species has its own form) and to help keep shrubs in the demonstration beds compact.
When to prune:
- Trees and shrubs – ideally after buds swell and before leaves emerge so sap will seal cuts (fall pruning may open the
plant to disease since no sap is running to seal cuts) but light pruning may be done any time of year
- Grasses may be pruned either after flowering to prevent reseeding or in the fall if you don’t want them for winter interest in your garden. If you wait until spring (like we have done), prune back as far as you can without damaging new growth.
- Wildflowers may be deadheaded after flowering to promote second blooms or to minimize reseeding, but leave at least half of the plant mass so the plant can accumulate sugar reserves it needs to make it through the winter. Some flowers like this Blue Columbine (Aquilegia coerulea) need to have old growth removed to make way for regrowth in the spring.
This Mockorange (Philadelpus lewisii) shrub needs to be thinned out to promote fewer healthy branches rather than lots of spindly suckers.
And of course, pruning provides cuttings for vegetative propagation which is a subject for another blog another day.