If there is one thing we get asked most about at Jersey Lavender, it has to be pruning lavender. For some reason people seem to think that there is some mysterious wizardry to it. There really is not. It is all pretty straight forward.
The issues are when and how hard, or not, to cut back! But before I go too far, just to be clear, the following comments apply to L. angustifolia (also known as “English” lavender, “True” lavender, lavender officinalis) and L. x intermedia (also known as lavandin, lavender hybrida). Other lavenders need different treatment.
So, firstly, the when. This blog is timely, because NOW is the time (if you are in the UK) to think about the pruning of your lavender. You need to prune when there is still some warmth in the air, when the plant is still actively growing. If you leave it too late, when it has turned cold and the plant has gone into its winter dormancy, it really will not thank you if you prune it then.
Then there is the how hard? The mistake most people make is to sort of tidy up the plant by trimming off the withered, grey, dry flower spikes and the stem, cutting down to to the top of the leaves. Granted, this leaves you with a satisfying-looking mound of neat foliage, BUT what you have left on the plant is that area of stem, about 3″, 10cm long, with those leaves on. Those leaves are this year’s growth, so if that is how you prune your lavenders, then each year they will put on 3″ or 4″ of growth, that eventually turns woody, and a few years later you have a have a rather strange-looking, woody, leggy, lavender plant that often collapses outwards, and looks nothing like the lovely compact plant that you had before!
Finally if you have let your lavender bush get a bit out of control and it has become woody and straggly at the base, then it is really time to pop down to the garden centre and get a new plant. There really isn’t much that you can do to salvage them. An alternative, before you dig it out is to take some cuttings to produce your own new lavender plants for your garden.
So the right way to prune is to be a little more brutal and cut off much of that leaf bulk. Cutting down to around the lowest set of leaves is about right. Often just below these leaves you see tiny, greyish buds. When the plant HAS leaves it doesn’t need to do anything with these buds. They are sort of “in reserve”. BUT when you prune off much of the leaf bulk these buds will really get going and push out new shoots. Also, wherever a leaf joins the stem, in the cleft between the two, you have a shoot node which will push out. You may also find rather straggly shoots from lower down, that cannot get enough light whilst all the flowers and leaves are on the plant. Prune off much of the leaf bulk and these shoots can finally get some light and strengthen up.
When pruned properly, you might stand back and go “Uh-oh, what have I done!” Believe me, your lavender plant will love it and bounce back with fresh foliage that will have a chance to slow down and prepare for winter as it gets colder. In fact, I believe that and annual pruning is THE most important maintenance job to carry out on your lavenders is you want them to be strong, healthy, compact plants year after year.