Are you wondering if pruning lavender can damage it? Or perhaps you are more of an expert but unsure when is the best time to trim it? Pruning usually takes just a few seconds, however, if done wrong, you might regret it for months to come ending up with a bare plant. Here how to get it right
Lavender should be pruned at least once a year. The best time to prune lavender is the end of the season (late summer) despite also the beginning of spring is an acceptable option. Lavender should be progressively pruned always above the woody area of the stem.
Let’s dive into the details on how to do it and avoid the most common pruning mistakes.
The first thing to understand is that lavender is a perennial shrub. This is important as it makes the difference in many aspects compared to soft annual plants such as basil or cilantro as it makes a significant difference in their stem, and so pruning.
Lavender stems present a green/brown softer part and a brown woody part. The woody part of the stem is the lower part while the green and softer part isat the top.
This is key for lavender growth and pruning. Indeed, over time the green softer part will grow in length and more of it will become (starting from the bottom) brown, woody, and hard to bend.
This means that over time, the woody part will grow. This is a sign of the aging of the plant that happens naturally.
However, pruning significantly slows down the lavender natural aging process (as in open nature lavender does not get pruned). This will make the plant last many more years than it would if unpruned.
You can think of the woody part of the lavender as a “less alive” part of the plant unable to carry out many of the functions of a green part of the stem. This is the old part of the plant. However, such a part carries the nutrients and gases to the upper part of the stem (the softer part).
Such a softer part of the lavender stem has the capability to reproduce and regrowth if cut. However, this is not the case for the wooden part that is already too old. This is very likely a defense mechanism that the plant evolved very similar to basil that, when pruned properly, can double its shoots.
Moreover, the green part of the plant is more active and “energetic” when there is more energy around.
Those two facts about the stems should give you a clear indication of the golden rules of pruning discussed below.
You are supposed to prune lavender to increase plant health and longevity. Now that you know the basics, it will be quite straightforward to understand how, when, and where to prune your lavender.
Lavender should be pruned on the flexible, greener part of the stem. Ideally, the cut should be done 3 to 4 nodes above the point where the woody part of the stem ends.
A node, in lavender (as any other plant) is the point where the leaves are produced in the stem.
Once defined where to cut, a pair of clean shear should be used. The orientation of the cut does not really matter. Important is to have a clean-cut, so a pair of sharp shears are recommended.
I usually use the one below, a pretty good brand and relatively cheap.
Lavender should be pruned at least once a year. The best time to prune lavender is the end of summer, around August in the northern hemisphere. The beginning of spring, around March in the northern hemisphere, once no more frosts are expected, is another option.
To note that pruning lavender on spring can delay blooming.
This is because the idea of pruning is to stimulate new growth. Hence, pruning at the beginning of a warm season with plenty of sunlight is the ideal condition for the plant to develop.
Lavender flowers should also be removed from the plant after blooming. This is the second pruning and happens after blooming.
Once the flowers have fully opened (since a week) they need to be pruned if you want to give lavender the opportunity of a second bloom. Hence, with a pair of shear, remove the whole flower stalk and 1 to 2 cm of the stem (with leaves).
The important is to prune too heavily (by removing an excessive amount of foliage) as this can create a dead-end (this is a stem that will turn black and die).
Now you know the basics (wood and green stem part). You also know when, where, and how often. However, many readers came back to me with questions on how to prune abandoned lavender or if cutting on wood is really a bad idea.
So I decided to collect below the best advice on how to troubleshoot your lavender with pruning plus some advanced advice (to apply on top of the basic one discussed above).
This principle, adopted by many gardeners (including myself) is based on the idea that lavender that has never been pruned before should be pruned more and more each time. This is a technique used to attempt to extend the lifespan of lavender plants that have not been pruned for many years (3 or more) by forcing growth at the lower part of the plant.
The progressive pruning technique requres to 1) prune lavender at the beginning of spring by cutting back one-third of the stem if it looks grey or dry 2) if new growth is noticed at the base of the plant cut back another third 3) if growth takes off at the base of the plant cut the stem above it.
This “gentle” pruning technique will force new growth to start lower and lower in the lavender stem reinvigorating the plant and make it last way longer.
Lavender not pruned for many years has lower and lower chances to have a long lifespan so, start pruning from the first year.
When pruning lavender, you will end up with the top of a lavender stem. This part, as the youngest of the stem, is alive and ready to grow!
To make lavender stem rooting 1) remove the leaves on the first third of the cut stem 2) place the part of the stem without leaves into the moist soil and 3) place on top a plastic bag (or one of those transparent plastic cup sold in the supermarket) to keep it warm.
Ideally, the lavender stem should be planted in a very draining, sandy soil to root. They should be placed in the shade if warm and sunny outside. If the plant is in zone 6 or higher, a plastic container such as a milk jug will be an ideal cover.
You should water in case the soil gets dry and wait for a few weeks. Remember, the more stems are planted, the higher chances to have a new lavender plant. Indeed, lavender stems have a lower chance of rooting compared to other plants.
This will allow having a quite bushier area ether on your planter or garden without buying new plants.
Young lavender plants (after 1 year) need to be pruned as well to promote busy growth that will guarantee lots of flowers in spring/summer.
Lavender is usually pruned twice if not three times a year. The last pruning of the season (late summer) is usually the one with the deepest cut to stimulate the maximum growth in the next season.
Lavender can be overpruned and this is a common mistake. When pruning lavender it is easy to be carried out by excessive hope and enthusiasm. Check below what over-pruning is and how to avoid it.
Lavender should never be pruned at the very base (the hardwood part) otherwise no growth will develop and the plant will die.
Every time lavender is pruned foliage should be let on the stem. The lavender should not be left without leaves otherwise the plant will not have the energy to develop and it will die.
If lavender is not pruned for a long time (2+ years) its wooden part will extend and it will have a shorter lifespan compared to a pruned one. Also, a not pruned lavender will look less bushy over the years.
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