Pruning Lavender: How, Why, and When (Plus 3 Mistakes to Avoid)
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 is 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. Pruning it in the beginning of spring is also an acceptable option. Lavender should be progressively pruned always above the woody area of the stem.
Let’s dive into the details of how to do it and avoid the most common pruning mistakes. Because if you prune it the wrong way, your lavender may end up dying and not coming back completely! Read this guide until the end to keep your lavender plants alive after pruning.
Pruning Lavender Stems The Right Way
Only the green soft stem portions of lavenders plants should be pruned. This is because the softer part of lavender stems have the capability to reproduce and regrow after being cut. However, this is not the case for the old wooden parts.
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 asoft brownish-green part and a woody brown part. Woody stem portions are by the base of the plant while soft stem parts are by the top. Over time, the softer green parts will grow in length and more of it will become brown, woody, and stiff from the bottom.
This means that over time, the woody part will grow. This is a sign of the aging of the plant that happens naturally. This is very likely a defense mechanism that the plant evolved very similar to basil that, when pruned properly, can double its shoots.
Pruning significantly slows down the natural aging process of lavender plants. This condition is similar to wild lavenders as they don’t naturally 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 the less active part of the plant. In other words, it’s unable to carry out many of the functions of a green part of the stems. This is the old part of the plant. However, such a part carries nutrients and gases to the upper soft part of the stem.
Moreover, the green part of the plant is more active when there is more energy around it.
Discover more about this plant in our article on lilac vs lavender!
Those two facts about the stems should give you a clear indication of the golden rules of pruning which I will be discussing in greater detail below.
Pruning Lavender: The Basics (4 Factors!)
Correctly pruning lavender plants involve 1) pruning only the green stems at least 3 nodes above the woody portions, 2) using a clean and sharp pruning shears, 3) doing so regularly late in summer or early in spring, and 4) removing flower stalks after the initial blooms.
You are supposed to prune lavender to increase plant’s health and longevity. Now that you know the basics, it will be quite straightforward to understand how, when, and where to prune your lavender.
1. Where to Prune 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 in any other plant) is the point where the leaves are produced in the stem.
2. How to Prune Lavender
Once defined where to cut, a pair of clean shears 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.
3. When to Prune Lavender
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.
Note that pruning lavender in 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.
4. Why Prune Lavender Flowers
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 (for a week) they need to be pruned if you want to give lavender the opportunity of a second bloom. Hence, with a pair of shears, remove the whole flower stalk and 1 to 2 cm of the stem (with leaves).
Is your lavender not blooming? Find out in our article on the 7 reasons why lavender isn't flowering.
The important thing to remember is to not prune too heavily. Don’t remove excessive amounts of foliage as this can create a dead-end. Excessively pruned stems will eventually turn black and die.
Progressive Pruning and Lavender: Advanced Methods
The progressive pruning technique requires pruning lavender by 1) cutting back one-third of the stem if it looks grey or dry at the start of spring, 2) cutting back another third if new growth is noticed at the base of the plant, and 3) cutting the stem above it if growth takes off at the base of the plant.
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.
This “gentle” pruning technique will force new growth to start lower and lower in the lavender stem reinvigorating the plant and making 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.
Replant the Cut Lavender Stems for More Plants!
To make lavender stem cuttings root 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 a plastic bag on top of the potted cutting to keep it warm.
When pruning lavender, you will end up with the top of a lavender stem. This part, as the youngest growth of the stem, is alive and ready to grow!
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 either on your planter or garden without buying new plants.
The 3 Biggest Mistakes in Pruning Lavender
Pruning lavender plants should be done properly to keep the plant healthy, do so by not 1) pruning woody stems, 2) cutting away all leaves, and 3) letting it grow without regular pruning.
Lavender can be overpruned and this is a common mistake. When pruning lavender it is easy to be carried out with excessive hope and enthusiasm. Check below what over-pruning is and how to avoid it.
1. Pruning Wood Stems
Lavender should never be pruned at the very base (the hardwood part) otherwise no growth will develop and the plant will die.
2. Cutting Off All Leaves
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.
3. Never Pruning Lavender
If lavender is not pruned for a long time—over 2 years, to be more exact—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.
Why should you prune young lavender plants early?
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.
When is the last best time to prune lavender?
Lavender is usually pruned twice if not three times a year but the last pruning of the season, done during the late summer months, is usually the one with the deepest cut to stimulate maximum growth in the next season.
Summary of Pruning Lavender
Lavender plants should only be cut on the soft mostly-green portions on their stems for proper pruning. Their stems can only be cut as low as 3 nodes above the brown woody parts by the base of the plant. Otherwise, plant could die completely when all the woody stems are cut off.
To prune lavender plants correctly home gardeners should also remember to use sharp pruning shears for a clean cut. Owners should also only prune their lavender while the plant is actively growing, as early as the start of spring and as late as summer. Remove spent flowering stalks to encourage second blooms.
- “Lavender: A must-have plant for all gardens” by Brittnay Haag in Illinois Extension
- “All About Lavender” by Jan Keahey, Muriel Stephenson, and Donna Marshall in the University of California Agriculture and Natural Resources
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