By Pat Dray
The Garden Spot
Pat Dray.
Spring flowering shrubs, defined as those that bloom before mid-June, are ready to be pruned now.
Spring bloomers, such as rhododendron, lilac, azalea and forsythia, form buds on last year’s stems or what you’ll hear called “old wood.” If you prune these shrubs earlier in the year, you’ll be removing this year’s flower buds and therefore have no flowers. This explains the common question of “Why didn’t my hydrangea bloom?”
Before you start any pruning, make sure that you have sterilized your tools by cleaning with rubbing alcohol so that you don’t carry disease from one plant to the next. When you move to another shrub, sterilize your tool again. I find keeping a spray bottle with some rubbing alcohol in it makes this ongoing sterilization process quick and easy.
There are two types of pruning – renewal and rejuvenation. Your first consideration on pruning is to identify any wood that is dead, diseased, damaged or “double crossed” (branches crossed). That observation will determine whether to renew or rejuvenate the plant.
Renewal pruning involves cutting back about one third of the large stems of the plant all the way back to the ground. This allows the shrub to keep its current shape while opening up the interior of the plant to more light and air circulation, which in turn will reduce plant diseases. Renewal pruning will also increase the amount of blooms on a shrub since older stems will tend to produce fewer blooms than the newer stems that will grow from the base of the shrub. Just be sure not to remove more than one third of the old wood so that you maintain the natural shape of the plant.
Rejuvenation pruning should be used on older plants that are no longer blooming. Take out your loppers and cut the entire shrub down to about six inches from the ground. You won’t have bloom for the first year after the rejuvenation, but by the second or third year you’ll have a new shrub. I also do this when I have a shrub that has excessive weather-related damage. It may seem harsh, but what do you have to lose if the shrub isn’t blooming anyway?
No matter whether you are renewing or rejuvenating a shrub, make your pruning cuts correctly at about a 45 degree angle. If you are pruning off dead or diseased wood, make the cuts into the healthy wood. It’s not necessary to use wound dressing or paint on the pruning cuts since these products don’t prevent decay or aid in healing.
Try to avoid shearing (or what I call giving your plants a haircut) since frequent shearing doesn’t encourage new growth from the base of the plant. It will result in a plant that has thick outer foliage growth that shades out the interior and bottom of the plant, leading to more plant disease and an unnatural looking shrub.
I hope these simple guidelines lead to healthier, more vigorously blooming spring shrubs.
Pat Dray is a past president of the Garden Club of Orange and a master gardener.