Pruning chores can frustrate gardeners when they are unsure of their knowledge. While they might understand that pruning improves the plant somehow, after they have devoted time and energy to growing the plant, trimming the plant’s growth might seem counter-productive.
Pruning the lavender plant puzzles many gardeners, so let us take a look at best practices.
We prune lavenders to stimulate new green growth, which produces flowers, and to slow the formation of older woody growth, which does not produce flowers. Traditionally, we prune lavenders to compact mounding forms that look attractive and yield maximum blooms.
There are two good times of the year to prune lavender plants: in the early spring, before they begin seasonal growth, and in the late summer, after their bloom period. Fall begins on September 22nd, so now is pruning time.
Here is a way to confirm that your lavender is ready to prune. Take a break in the garden, sit quietly near your lavender plant(s) and watch the bees. If they flit from blossom to blossom without lingering to feed, you will know that the blooms are finished for the year and it is pruning time.
Pruning shears will do the job, but use hedge shears to make quick work of pruning. When pruning several lavender plants, an electric hedge trimmer will be the tool of choice.
In any case, ensure that the pruning tool is sharp enough for clean cuts, and wipe it down between plants with rubbing alcohol or bleach to remove any harmful bacteria or germs.
When pruning, remove about one-third of the green growth to stimulate new growth. Do not cut into the woody stems: they will not produce new green growth and cutting too deeply could kill the plant.
If you have the time and patience for precision pruning, cut just above the third node above the woody part of the stem. Most gardeners will keep this rule of thumb in mind without actually counting nodes on each stem.
This process should be repeated in the early spring.
Start this twice-yearly pruning schedule when the plant is still young, i.e., the second year after putting a new plant in the ground. This delay allows time for the plant to establish its roots.
Gardeners might encounter a lavender plant that has not been pruned routinely for three years or more and has become rangy and unattractive, with long woody stems and minimal blossoms. Sadly, the plant cannot then be pruned to rediscover the preferred tight mound form, and should be replaced.
With these guidelines, the gardener will find pruning lavenders quick and easy, and finish the task with a nice fragrance from the lavender’s aromatic oils.
Enjoy your lavender!
There are minor differences in pruning recommendations for the various species of lavender. For this reason, the gardener should be aware of the particular species that is to be pruned.
The most popular species of lavender for residential gardening are English Lavender (Lavandula angustifolia), French Lavender (L. dentata) and Spanish Lavender (L. stoechas). Another form that may be seen is Lavandin or Hedge Lavender (L. x Intermedia), which is a cross (hybrid) of English Lavender and Spike Lavender (L. latifolia).
English Lavender’s flower petals unfurl along much of the length of its long stocks. Its green, narrow leaves largely lack the silver and gray cast of the other varieties. It is available in several cultivars. Sunset’s Western Garden Book lists the following: Alba, Blue Cushion, Buena Vista, Compacta, Hidcote, Jean Davis, Lady, Martha Roderick, Melissa, Munstead, Rosea, and Thumbelina Leigh. A light pruning after early-summer flowering often will promote reblooming later in the summer. In late summer, cut back to one-third or even one-half of stem length, as outlined above.
French Lavender has looser-looking, light purple flowers. Their grayish leaves appear more serrated (or dented) than those of their Spanish cousin (the specific name dentata means “toothed”). Prune after flowering remove about one-third of stem length.
Spanish Lavender has tight, deep purple blooms that are shaped like pine cones. Four petals reach skyward, distinctly shaped like rabbit ears. The flower spikes are highly compressed and surmounted by showy, large, sterile bracts. Some varieties have white flowers. The bushes grow about 18 inches tall, with silvery-green leaves. Cultivars include Hazel, Kew Red, Otto Quast, Willow Vale, Wings of Night and Winter Bee.
Hedge Lavender cultivars are Abrialii, Dutch, Fred Boutin, Grosso, Provence, Silver Edge, White Spikes, and others.