French Lavender Pruning Starts With Which Plant You Have
Before any advice about cutting is useful, it is worth knowing which plant you own. Two different lavenders are sold as French lavender, and they flower on different schedules.
This guide identifies them, explains why lavender cannot regrow from bare wood at all, gives the two cuts a year that keep this species domed rather than splayed, and covers getting the least hardy lavender in the family through winter.
Two Different Plants Are Sold as French Lavender
Two different plants are sold as French lavender, and there is a fair chance the one in your pot is not the one you searched for.
Lavandula dentata is French lavender in the botanical sense. Dentata means toothed, and that is exactly what its gray-green leaf margins are, scalloped along both edges in a way no other common lavender shares.
Lavandula stoechas is Spanish lavender, and it is the one everybody recognizes. Its flower head is a squat purple cone topped by two or three long upright bracts that stand up like rabbit ears.
Check the leaf rather than the flower, because it settles the question in a second. Toothed edges mean dentata, and plain narrow smooth-edged leaves with eared flower heads mean stoechas.
If it turns out to be stoechas, the Spanish lavender guide is the one you want, because that plant reblooms on a different schedule and is pruned to take advantage of it.
What does not change is the cut line. All three lavenders share the same rule about leafless wood, so a misidentification costs you timing rather than the plant.
| Species | Leaf | Flower head | Hardiness |
|---|---|---|---|
| French, Lavandula dentata | Gray-green with toothed edges | Slender spike, small bracts | Least hardy |
| Spanish, Lavandula stoechas | Plain, narrow, smooth edged | Squat cone with long upright ears | Tender |
| English, Lavandula angustifolia | Plain, narrow, smooth edged | Slim spike, no ears | Much hardier |
Why Cutting Into Bare Wood Kills It
Never cut back into bare leafless wood. That rule appears on every lavender page and almost none of them say why it holds, which leaves the reader guessing at distances instead of reading the plant.
Lavender has almost no dormant buds in old wood, which is the whole explanation. Most shrubs carry latent buds under the bark that break when the top is removed, which is why a boxwood or a hydrangea tolerates hard renovation and lavender does not, a difference worth remembering whenever renovating anything else in the border.
The bare zone at the base grows a little taller every year the plant goes uncut, so an unpruned lavender slowly becomes an unprunable one.
Find the line by looking rather than measuring. Follow each stem down until the lowest green leaves stop, and cut above that point on every stem rather than to a fixed height across the plant.
Cut below it and the stem is gone. The plant will not fill that space again, which is why one careless renovation can permanently ruin a dome that took years to build.
Two Cuts a Year Keep the Dome
French lavender flowers on soft new growth and goes woody faster than any English type, so one annual tidy is not enough for it. Two cuts a year is the routine that keeps it domed.
The first cut follows the main flush of flower. Take the plant back into a rounded dome of green growth, removing the spent spikes and roughly the top third of the soft growth with them.
The second is lighter and later. It clears the spikes that came after the first cut and holds the shape going into autumn, and it is a tidy rather than a reshape.
Aim for a dome rather than a flat top, because a domed plant sheds water and keeps its center closed. A flat or hollowed top collects water and the plant splays open from the middle, which is the same failure that opens up an unpruned catmint or russian sage.
Between the two cuts, spent spikes can come off individually as they go over, and how deep to cut a spent spike follows exactly the same green-wood rule as the main prune.
Stop cutting hard well before the season ends. A late hard cut pushes soft growth that will not harden in time, which matters more on this species than most because it is the least cold hardy of the family.
- First cutStraight after the main flush. Take off spent spikes and about a third of the soft growth, shaping into a dome.
- Between cutsSnip individual spent spikes as they go over, always into green growth.
- Second cutA lighter tidy later in the season to clear late spikes and hold the shape.
- Check every stemCut above the lowest green leaves on each one rather than to a single height.
- Stop in timeNo hard cutting late in the season, since soft growth will not harden before cold.
It Is the Least Hardy Lavender in the Family
This is the least cold hardy lavender in common cultivation, noticeably more tender than English lavender and its hybrids, and pruning and winter survival really are one problem for it.
What kills it is usually not the cold on its own. Winter wet sitting around the crown finishes more of these plants than low temperature does, which is why a plant in heavy ground dies while the same variety in a gritty pot survives a harder winter.
Work through the options in order of effort. Sharp drainage and a gravel mulch at the base cover a mild winter, moving a pot against a sheltered house wall covers a colder one, and lifting the plant into an unheated porch or greenhouse covers the rest.
Do not wrap the foliage. Plastic over the top traps moisture against the plant and rots it faster than the weather would have, so wrap the pot for insulation and leave the top open.
- Hardiness
- Least hardy of the common lavenders
- Real killer
- Winter wet at the crown, not cold alone
- Mild winter
- Sharp drainage and gravel mulch
- Colder winter
- Pot moved against a sheltered wall
- Coldest
- Lift into an unheated porch or greenhouse
- Never do
- Wrap the foliage in plastic
When a Woody Plant Is Past Saving
Look at how far down the green still runs before deciding anything. If leafy growth reaches low on the stems, the plant can be brought back over two seasons by cutting a little further each year, always staying in green wood.
If the lower two thirds are bare gray wood there is nothing left to cut back to, and a young replacement will be a better plant within a season than the rescue would be in three. The same reasoning applies to the other woody herbs, since rosemary and sage both refuse to break from bare wood in exactly the same way and are covered in pruning herbs by habit.
Pro Tips
- Check the leaf before you cut. Toothed edges mean true French lavender and plain narrow leaves with eared flowers mean Spanish.
- Follow each stem down to its lowest green leaves and cut above that, rather than shearing the whole plant to one height.
- Prune twice a year rather than once, since this species goes woody faster than English lavender.
- Shape into a dome rather than a flat top, so the plant sheds water instead of collecting it in an open center.
- Stop hard cutting well before the season ends, because soft late growth will not harden in time on a tender plant.
- Wrap the pot for winter and leave the foliage open, since plastic over the top rots the plant faster than cold does.
Frequently Asked Questions
Is French lavender the same as Spanish lavender?
No, although both are sold under the name French lavender depending on the market. Lavandula dentata is the true French lavender and has toothed gray-green leaves, while Lavandula stoechas is Spanish lavender and carries a squat flower head topped by long upright bracts like rabbit ears.
How far back can I cut French lavender?
Never below the lowest green leaves on a stem, because lavender has almost no dormant buds in old leafless wood and a cut below that line has nothing to resprout from. Follow each stem down to where the green stops and cut above that point rather than to a fixed height across the plant.
How often should I prune French lavender?
Twice a year, which is more than English lavender needs, because it flowers on soft new growth and goes woody faster. Cut it back into a dome after the main flush and give it a lighter tidy later in the season.
Why did my lavender die after I cut it back?
Almost always because the cut went into bare wood below the lowest leaves, which lavender cannot regrow from. Those stems die back completely and leave permanent gaps, which is why an old plant with a tall bare base cannot be renovated the way most shrubs can.
Will French lavender survive winter outside?
It is the least hardy of the common lavenders, and what usually kills it is winter wet around the crown rather than cold alone. Sharp drainage and a gravel mulch handle a mild winter, a sheltered wall handles a colder one, and lifting it into an unheated space handles the rest.
Can I save a woody French lavender?
Only if green growth still runs low on the stems, in which case cutting a little further into green wood each year can rebuild the shape over two seasons. If the lower two thirds are bare gray wood there is nothing to cut back to and a young replacement will outperform the rescue.
Sources & References
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