How do I prune old, woody lavender plants for rejuvenation?

Rejuvenating an old, woody lavender plant can be a bit of a gamble, as lavender generally doesn't readily sprout new growth from old, bare wood. However, it's definitely worth a try, especially if the alternative is discarding the plant. The key is to be strategic and patient.

The best time to attempt rejuvenation pruning is in early spring, just as new green growth begins to emerge from the base or lower parts of the plant, and after all danger of hard frost has passed. Pruning too early can expose fresh cuts to cold and kill any nascent new growth.

Here's a step-by-step approach for attempting to rejuvenate an old, woody lavender plant:

1. Assess the Plant's Condition:

Before you grab your pruners, get up close and personal with your woody lavender:

• Look for Green Shoots: Carefully examine the base and along the woody stems. Are there any tiny green shoots emerging from the old wood, particularly near the ground? This is your best indicator of success. If you see some, it's a good sign the plant still has life and can potentially regenerate.

• Scratch Test (Optional): Gently scratch the surface of a woody stem with your fingernail. If you see green underneath, that part of the stem is still alive. If it's brown and dry, it's likely dead wood.

• Overall Health: Is the plant otherwise healthy? Does it have good color in the green parts, or does it look generally stressed and weak? A plant that's otherwise struggling might not have the vigor to recover from a hard prune.

2. Choose Your Strategy:

There are two main approaches, depending on the severity of woodiness and your risk tolerance:

Option 1: Gradual Renovation (Safer, Recommended for Less Severe Woodiness)

This method spreads the pruning over 2-3 years, causing less stress to the plant.

1. Year 1 (Early Spring):

   • Remove Dead Wood: Start by cutting out any clearly dead, brittle, or completely bare woody stems that show no signs of life, cutting them back to the ground or to where they meet a healthy main stem.

   • Reduce by One-Third: On the remaining live, woody stems, identify where green growth emerges. Cut back about one-third to one-half of the length of these lanky, woody stems, always cutting just above a node (where leaves emerge) or above a cluster of new green shoots. The goal is to encourage branching and new growth from lower down.

   • Open the Center: If the center of the plant is very dense and woody, selectively remove a few of the oldest, thickest internal stems to improve air circulation. Again, cut them just above a point of new green growth if possible.

   • Shape: Aim for a more compact, rounded shape.

2. Year 2 (Early Spring):

   • Assess the plant's recovery. If it responded well with new growth, continue with the same approach, pruning back another portion of the remaining old woody stems that you left in Year 1.

   • Again, cut above green growth or potential bud sites.

3. Year 3 (Early Spring):

   • Continue to prune back remaining old wood if the plant continues to respond positively.

Option 2: Hard Rejuvenation / "Hack Back" (Risky, for Very Woody Plants)

This is a more drastic approach and carries the risk of killing the plant, as lavender doesn't reliably regrow from entirely bare, old wood. However, if the plant is very unsightly and you're prepared to lose it, it's worth a try. This is best done only if you see some definite signs of new green growth emerging from the very base of the plant.

1. Early Spring:

   • Identify stems with even a tiny bit of green growth low down, or promising bud nodes.

   • Cut back severely: Cut stems back significantly, aiming for about 4-6 inches (10-15 cm) from the ground, or just above visible new shoots or nodes if they are higher up.

   • Focus on the Base: The aim is to remove most of the unproductive woody top growth and force the plant's energy into new growth from the base.

   • Expect it to look brutal: The plant will look very sparse, possibly just like stumps.

Important Considerations for Rejuvenation Pruning:

• Timing is Key: As mentioned, early spring is the best window.

• Sharp, Clean Tools: Always use bypass pruners or loppers that are sharp and sterilized with rubbing alcohol or a bleach solution to prevent disease transmission.

• No Guarantee: Be aware that there's no guarantee the plant will recover, especially if it's extremely old, severely woody with no visible green growth, or has been stressed.

• Aftercare:

  • Watering: Water the plant thoroughly after pruning to help it recover. Ensure continued good drainage.

  • No Fertilizer: Do not fertilize after hard pruning. Lavender prefers lean conditions, and excess nutrients, especially nitrogen, will encourage weak, leggy growth rather than strong regeneration.

  • Patience: It will take time for the plant to recover and put on new growth. Don't expect immediate results.

• Consider Cuttings as Insurance: If you're attempting a risky hard prune on a beloved plant, take some cuttings from any healthy green growth before you prune. This way, if the mother plant doesn't survive, you'll have new plants to replace it.

While it's best to prevent extreme woodiness with consistent annual pruning from a young age, attempting to rejuvenate an old lavender can sometimes yield surprising and rewarding results.

Lavender Farm in Door County Wisconsin. You can buy lavender products online at islandlavender.com