How to Prune Lavender Plants

1. Pruning Young Lavender Plants

   Start pruning lavender plants while they're still young. Begin by pinching off tips of new growth, so that a young plant can respond with dense branching that helps form a good shape and a lot of blooming growth to work with as it matures. Waiting to prune will cause the plant to form woody growth that can't be shaped as nicely.

2. Pruning Established Lavender Plants

   Heavily prune established lavender, cutting back all stems by at least a third after the plant is finished flowering for the season. Lavender in full sun can be expected to grow vigorously each year, so take this opportunity to reform your plants into the green mounds that are lavender’s signature shape. You can use hand pruners or pruning shears. Shears are less precise than hand pruners, but they save time and are a necessity if you are creating or maintaining a lavender hedge.

3. Pruning Old Lavender Plants

   Continue to heavily prune old plants, but don’t cut down to leafless wood. You can’t rejuvenate plants by cutting into old wood, but you can try to rejuvenate them by pruning to points just above the wood. A good rule of thumb is to count to the third node (raised bump from which leaves grow) above the woody part, and then cut just above it. If you are lucky, all three nodes, as well as some hidden nodes buried in the wood, will wake up and grow for you.

4. Guidelines for Specific Varieties

   Identifying your lavender variety and tailoring pruning to that type will help you get even more return for your efforts. There are three common types of lavender:

   Lavandula angustifolia: English lavender comes in many varieties, including 'Hidcote' and 'Munstead.' This lavender has single, leafless stems and compact spikes of blossoms. It is generally low-growing and has a compact, mounded shape. English lavender blooms in late spring to early summer. If it's pruned lightly just after its first flowering, it will likely flower again in late summer. After this second flowering, a full pruning—typically in late August—will prepare it for winter and encourage more blooms in spring.

   Lavandin x intermedia: This hybrid of English and spike lavenders also has many varieties. The most common are 'Grosso,' 'Provence,' and 'Giant Hidcote.' Its stems are branched and longer than those of English lavender. The flower spikes also are longer, and they have a graceful taper. Lavandins are mounded in shape and usually larger than English lavender. And the long stems tend to fan out from the center. Lavandins bloom in mid- to late summer, and a full pruning after the long blooming season will prepare a plant for winter. Because of the long stems, you might need to prune as much as half the plant’s size.

   Lavandula stoechas: Sometimes called Spanish or French lavender, this is the least hardy of the lavenders. And it blooms the earliest in spring. Spanish lavender has a short, full flower spike with open petals at the top, distinguishing it from other types. Because of its fragility, lightly prune this lavender—never too close to the base—just after the first flowering. Then, follow up with gentle deadheading (removing spent flowers) and shaping for the rest of the season. A slightly more vigorous pruning can be done in late August to prepare the plant for winter and encourage a fuller plant in spring.

Working With Lavender Plants

Lavender is regarded as a semi-shrub or subshrub—a plant that looks like a perennial because most of its growth is soft and green but older base stems turn to wood. Knowing this is going to help you prune your lavender.

Deep at the center of the mounded semi-shrub, your lavender plant is trying to turn to wood. One goal of pruning lavender is to slow down that transformation for several reasons:

• Lavender wood is very weak and prone to splitting due to snow, ice, and rot.
• Lavender is shallow-rooted, which means roots are more susceptible to rot and early death due to too much moisture.
• Regular pruning encourages root growth, especially during the winter months when the plant is storing energy in the roots. A strong root system is essential for a lavender plant to thrive for many years.
• Unlike many true shrubs and trees, the wood that forms on lavender usually does not rejuvenate. Old wood will stop producing new shoots or will produce spaced-out shoots, detracting from the plant's overall appearance.

When to Prune Lavender

The best time to prune lavender is after flowering is complete, but this plant is forgiving. All lavenders bloom on the stems that grew in the current year. This means pruning can be done in early or mid-spring without sacrificing the current year’s flowers.

Pruning in spring can delay flowering—which might be your preference—and it's a good time to take down dead portions and shorten growth to the buds. Pruning in late summer or early fall before the first frost encourages good air circulation, which guards against rot. So if you have the time, pruning twice a year can be helpful for your plant.

Tips for Pruning Lavender

Pruning is generally necessary for the health of a lavender plant. Not pruning lets a plant get large and woody, and it forms nooks that trap water. This can introduce several hazards:

• In summer, trapped water promotes rot in lavender's weak stems and wood.
• In late autumn, trapped water promotes an early frost, ending the growing season prematurely.
• In winter, trapped water can freeze, easily splitting woody parts. Plus, a dense plant or one with sprawling wood is especially vulnerable to snow loads, which can deform or break plants.

So keep an eye on your lavender plant throughout the seasons, and remove parts that might cause problems.