Can You Split Lavender Plants? - Plant Care Guide

Yes, you can split (divide) lavender plants, but it's generally not the most recommended or easiest method of propagation, especially for older, woody plants. Lavender, particularly English lavender (Lavandula angustifolia), tends to develop a woody crown over time, making it difficult to divide successfully. While possible for young, more herbaceous plants, taking cuttings is usually a much more reliable and successful method for propagating lavender and creating new, healthy plants.

What is plant division and which plants typically respond well to it?

Plant division is a method of asexual (vegetative) propagation where a gardener physically separates a single, larger plant into two or more smaller plants, each with its own root system and crown. This technique is distinct from taking cuttings or planting seeds, and it typically works best for plants that grow in clumps.

What is Plant Division?

• Process: It involves carefully digging up an entire mature plant and then splitting its root ball and crown into multiple sections using hands, knives, or spades. Each section should have a sufficient amount of roots, stems (or foliage), and growing points to survive independently.
• Asexual Reproduction: Because it involves splitting a part of the parent plant, the new plants created through division are genetically identical clones of the original plant.

Which Plants Typically Respond Well to Division?

Plants that respond well to division typically share certain characteristics in their growth habit and root structure. They are often herbaceous perennials that grow in clumps rather than developing a single, woody stem or taproot.

Here are the types of plants that are ideal for division:

1. Clumping Perennials:

   • Characteristic: These plants naturally expand outwards from a central crown, forming a larger clump over time. They have fibrous root systems that can be easily separated.
   • Examples: Hostas, Daylilies, ornamental grasses (e.g., Liriope, many Fescue varieties), Irises (rhizomatous types), Coneflowers (Echinacea), Shasta Daisies, Peonies (with care), many ferns.

2. Plants with Spreading Rhizomes or Stolons (Some):

   • Characteristic: Some plants that spread by underground rhizomes or above-ground stolons can also be divided, as you can simply cut sections of the runner with roots attached.
   • Examples: Mints (though often invasive, they respond well), some groundcovers.

3. Plants with Multiple Crowns:

   • Characteristic: Over time, a single plant might develop multiple distinct crowns, each capable of sustaining a new plant.
   • Examples: Phlox, Astilbe, Coreopsis.

Why Division is Beneficial:

• Rejuvenation: Mature plants often become overcrowded, leading to reduced vigor, fewer flowers, or even a "dead spot" in the center. Division rejuvenates the plant, promoting healthier, more vigorous growth.
• Propagation: It's an easy and cost-effective way to create new plants for free, to fill in other garden areas, or to share with friends.
• Improved Flowering: Dividing overcrowded plants often leads to improved flowering, as competition for resources is reduced.
• Maintains Health: Helps manage the size of vigorous clumps.

Why Division is NOT Ideal for Some Plants (like older Lavender):

• Woody Shrubs: Plants that develop a single, woody stem or a deep taproot (e.g., trees, many shrubs, taprooted perennials like Baptisia) do not typically respond well to division.
• Lavender: Older lavender plants develop a woody, often hollow, central crown. Attempting to split this woody mass is difficult, damages the plant severely, and often results in little viable material for new plants, leading to a low success rate.

Understanding which plants are amenable to division is key to successful propagation and maintaining a healthy, vibrant garden.

Why is lavender generally difficult to divide successfully, especially older plants?

Lavender is generally difficult to divide successfully, especially older plants, primarily because of its woody growth habit, dense root system, and the formation of a rigid central crown. These characteristics make it fundamentally different from the herbaceous perennials that respond well to division.

Here's why lavender division is challenging:

1. Woody Crown and Stem Structure:

   • Shrub, Not Herbaceous: Lavender is a sub-shrub, meaning its stems become woody and lignified (like tree branches) over time, particularly at the base. It doesn't have the soft, fleshy crowns and easily separable fibrous roots of herbaceous perennials (like Hostas or Daylilies).
   • Rigid Core: An older lavender plant develops a solid, often gnarled and woody central crown that is extremely difficult to cut through cleanly.
   • Lack of Natural Divisions: Unlike clumping perennials that naturally expand with multiple distinct growth points, lavender often maintains a singular, woody base.

2. Dense, Intertwined Root System:

   • Fibrous and Tough: Lavender develops a dense, fibrous root system that can be quite tough and intertwined, making it hard to tease apart individual sections without causing significant damage.
   • Lack of Clear Separation Points: There are often no clear, natural planes of separation within the root ball, forcing a destructive approach rather than a gentle division.

3. Fragile Woody Stems:

   • When trying to physically split an older, woody crown, the attached stems are brittle and prone to breaking or tearing, often without any viable roots attached.

4. Poor Recovery from Root Disturbance:

   • Sensitive to Damage: Lavender plants, especially mature ones, do not respond well to severe root disturbance or damage. Their woody nature means they have a harder time regenerating new feeder roots from damaged sections compared to herbaceous plants.
   • Transplant Shock: They are very susceptible to transplant shock, and the trauma of division can be too much for an older plant to overcome, often leading to decline and death.

5. Risk of Disease:

   • Large, open wounds created by forcibly splitting a woody crown can become entry points for soil-borne diseases, further compromising the plant's survival.

Alternative and Recommended Propagation Methods:

Given these difficulties, taking cuttings is by far the preferred and more successful method for propagating lavender. Cuttings allow you to start with fresh, young, flexible growth that roots readily, creating healthy new plants without risking the parent plant. Layering is another gentler method for producing new plants directly from the parent.

While technically you can try to divide a very young (1-2 year old), less woody lavender plant that shows some natural splitting, the success rate is still lower than for herbaceous perennials, and it becomes increasingly difficult and detrimental with age.

What is the best time of year to attempt to split a lavender plant?

The best time of year to attempt to split a lavender plant, if you choose to try this method despite its challenges, is in early spring, just as new growth is beginning to emerge from the base of the plant. This timing leverages the plant's natural surge of energy for growth and provides the longest possible recovery period.

Here's why early spring is the optimal, albeit still risky, time:

1. Before Active Growth (Energy Reserves):

   • In early spring, the lavender plant is emerging from its winter dormancy. It has stored energy reserves in its roots that it will use to push out new growth.
   • Dividing at this stage allows the newly separated sections to immediately begin channeling this energy into root regeneration and establishment in their new locations.

2. Avoids Summer Heat Stress:

   • Splitting in early spring ensures the plants have the entire spring and early summer to establish their root systems before facing the heat and potential drought stress of mid-summer. Transplanting a stressed plant into hot, dry conditions is often fatal.

3. Avoids Winter Cold Stress:

   • Dividing in fall is generally not recommended for lavender. The plants wouldn't have enough time to establish sufficient roots before winter cold sets in, making them highly susceptible to frost heave and winter kill.

4. Easier to Assess Viable Sections:

   • While the plant isn't in full leaf, the emergence of early new shoots makes it easier to identify viable sections of the crown that have active growth points, ensuring each division has a chance of survival.

How to Prepare (to Maximize Slim Chances):

• Choose Young, Less Woody Plants: Only attempt division on relatively young (1-3 year old), smaller lavender plants that haven't developed an overly woody central crown.
• Water Well: Water the plant thoroughly the day before you plan to divide it. Moist soil is easier to work with and reduces stress.
• Gather Tools: You'll need a sharp spade, a sturdy garden fork, and potentially a very sharp, clean knife or pruning saw if the crown is woody.

Important Note on Risk: Even with optimal timing, dividing lavender is a high-risk operation compared to other propagation methods. Be prepared for a low success rate, especially with older plants. If the parent plant is highly valued, it's often wiser to take cuttings instead.

What is the step-by-step process for dividing a young lavender plant?

The step-by-step process for dividing a young lavender plant involves careful excavation, gentle separation, and proper replanting to give the new divisions the best chance of survival. This method is best attempted on smaller, less woody plants.

Estimated Time: 30-60 minutes per plant. Best Time: Early spring, just as new growth begins.

Materials Needed:

• Young (1-3 year old), healthy lavender plant
• Sharp spade or garden fork
• Clean, sharp knife or pruning saw (for woody crowns)
• Rubbing alcohol or bleach solution (for sterilizing tools)
• Gloves
• Prepared planting holes or pots with well-draining soil
• Watering can

Step-by-Step Instructions:

1. Prepare the Parent Plant:

   • Water: Water the lavender plant thoroughly the day before you plan to divide it. This makes the soil easier to work with and hydrates the plant.
   • Prune (Optional): You can lightly prune back some of the top growth by about one-third. This reduces the stress on the root system after division, as the roots will have less foliage to support.

2. Prepare New Planting Sites or Pots:

   • Well-Draining Soil: Lavender requires extremely well-draining soil. Ensure your new planting holes or pots are prepared with a gritty, sandy loam mix or a potting mix amended with plenty of perlite or coarse sand.
   • Space: Dig holes or prepare pots for immediate planting of your divisions.

3. Carefully Dig Up the Parent Plant:

   • Tools: Using a sharp spade or garden fork, dig a wide circle around the lavender plant, at least 6-8 inches (15-20 cm) away from the base, to minimize root damage.
   • Lift Gently: Carefully lever the entire root ball out of the ground, trying to keep as much soil attached as possible.

4. Inspect and Separate the Root Ball:

   • Gentle Approach: Gently shake off some of the excess soil to expose the root crown.
   • Identify Natural Divisions: Look for natural sections or multiple distinct clumps of growth. Young lavender might have a few separate sections.
   • Method of Division:
     • For soft, pliable roots: You might be able to gently pull apart sections with your hands.
     • For slightly tougher clumps: Use a sharp, sterilized knife or pruning saw to cut through the crown, ensuring each new section has a good amount of healthy roots and several stems (or active growth buds). Avoid tearing woody sections aggressively.
   • Aim: Each division should be a viable plant with its own root system and some top growth.

5. Prepare the Divisions:

   • Prune Roots (Optional): Trim off any damaged, dead, or excessively long roots from each division.
   • Prune Foliage (Optional, for woody plants): If you didn't already, lightly prune the top foliage of each division by about one-third. This helps reduce transpiration and redirects energy to root establishment.

6. Plant the Divisions Immediately:

   • Depth: Plant each division into its new prepared hole or pot, ensuring the top of the root ball is level with the surrounding soil surface. Do not plant too deep.
   • Backfill: Backfill with your well-draining soil, gently firming it around the roots to eliminate air pockets.

7. Water Thoroughly:

   • Immediately after planting, water each newly divided plant deeply and slowly. This settles the soil and provides essential moisture for recovery.

8. Post-Division Care:

   • Shelter: Place container-grown divisions in a sheltered spot (bright, indirect light, out of strong wind) for a few days to recover from transplant shock.
   • Consistent Moisture: Keep the soil consistently moist (but not soggy) for the first few weeks, as the plants work to establish new roots. Use a soil moisture meter.
   • No Fertilizer: Do not fertilize for at least 4-6 weeks after division.

By carefully following these steps on a young, less woody lavender plant, you can maximize your chances of successfully creating new divisions.

What are the most reliable methods for propagating lavender?

Given the difficulty of successful division, the most reliable methods for propagating lavender are stem cuttings and layering, both of which leverage the plant's ability to root from its stems. These asexual (vegetative) propagation techniques ensure new plants are genetically identical clones of the parent.

Here are the most reliable methods:

1. Stem Cuttings (Most Popular and Effective):

This is the easiest and most successful method for most home gardeners.

1. Timing: Take cuttings from late spring through mid-summer (when the plant is actively growing).
   • Softwood Cuttings: Taken from new, flexible, non-flowering growth in late spring/early summer. These root quickly but can be more prone to wilting.
   • Semi-Hardwood Cuttings (Recommended): Taken from slightly more mature, firm, but still flexible stems (this year's growth that has started to harden a bit) in mid to late summer. These are generally more reliable.
2. Select and Prepare Cuttings:
   • Choose healthy, non-flowering stems that are 3-5 inches long.
   • Make a clean cut just below a leaf node (where leaves emerge).
   • Remove all leaves from the bottom 1-2 inches of the stem.
   • Gently scrape a small sliver of bark from one side of the bare stem (optional, but can encourage rooting).
3. Apply Rooting Hormone (Optional, but Recommended):
   • Dip the cut end into rooting hormone powder or gel. Tap off excess.
4. Plant in Rooting Medium:
   • Insert the prepared cuttings into a small pot or tray filled with a well-draining, sterile rooting medium (e.g., 50/50 perlite and peat moss/coco coir, or pure coarse sand).
   • Moisten the medium lightly.
5. Provide Optimal Conditions:
   • Place cuttings in a location with bright, indirect light and consistently warm temperatures (65-75°F / 18-24°C).
   • High Humidity: Cover the pot/tray with a clear plastic bag or a humidity dome to maintain high humidity (ensure some ventilation).
   • Consistent Moisture: Keep the rooting medium consistently moist but never soggy.
6. Rooting Time: Cuttings typically root in 4-8 weeks. Gently tug to check for resistance.

2. Layering (Simple Layering):

This method is very reliable as the new plant remains attached to the parent plant while rooting.

1. Timing: Best done in spring or early summer with new, flexible growth.
2. Select a Stem: Choose a healthy, long, low-growing stem that can easily bend to the ground.
3. Prepare the Stem:
   • About 6-12 inches from the tip, gently scrape off about an inch of bark from the underside of the stem.
   • You can apply rooting hormone to this wounded section (optional).
4. Bury the Stem:
   • Dig a shallow trench (2-3 inches deep) in the soil next to the parent plant.
   • Bend the wounded part of the stem into the trench and bury it with soil, leaving the tip of the stem exposed above ground.
   • Secure the buried stem with a landscape staple or a rock to keep it in contact with the soil.
5. Consistent Moisture: Keep the buried soil consistently moist.
6. Rooting Time: Roots will typically form over several months. You may feel resistance if you gently tug.
7. Separate and Plant: Once well-rooted (often by fall or the following spring), sever the new plant from the parent, carefully dig it up, and transplant it to its new location.

Table: Reliable Lavender Propagation Methods

Both stem cuttings and layering are excellent ways to expand your lavender patch, providing a much higher success rate than attempting to divide mature, woody plants.

What happens to an old lavender plant that is left undivided or unpropagated?

An old lavender plant that is left undivided or unpropagated will typically become overly woody, leggy, sparse in foliage, and produce fewer, weaker flowers, eventually declining in vigor and potentially dying. Unlike clumping herbaceous perennials that are rejuvenated by division, lavender's woody nature makes this less effective, highlighting the need for regular pruning and propagation by cuttings.

Here's what happens to an old, unpropagated lavender plant:

1. Increased Woodiness:

   • Structural Change: Over time, lavender's stems become increasingly woody and brittle, especially at the base. This is a natural part of its growth as a sub-shrub.
   • Reduced Productivity: Woody stems are less productive. New flowers and foliage primarily grow on green, new wood. As the plant ages and the woody framework dominates, the proportion of new, active growth diminishes.

2. Legginess and Sparse Foliage:

   • Open Center: The woody stems become long and bare at the base, leading to a leggy, open, and often unsightly plant with foliage concentrated only at the tips of branches.
   • Reduced Density: The dense, compact form that makes lavender so attractive is lost, and the plant becomes sparse and straggly.

3. Fewer, Weaker Flowers:

   • Reduced Vigor: With more woody growth and less vigorous new growth, the plant's overall energy declines.
   • Impact: This results in fewer flower spikes, and those that do appear may be smaller, less vibrant, and have a reduced fragrance compared to a younger, healthy plant. The main reason for growing lavender is its beautiful blooms, so this is a significant drawback.

4. Decreased Overall Health and Vigor:

   • An old, woody plant is often a less vigorous plant. Its internal structure is less efficient, and it may be more susceptible to environmental stress, pests, and diseases.

5. Poor Response to Pruning:

   • Pruning into Old Wood: Lavender generally does not reliably sprout from old, woody stems that have no green leaves or active growth buds. Pruning an old, leggy plant back too hard into old wood can kill it, as it lacks the dormant buds to regenerate. This creates a dilemma: you can't prune hard enough to reshape it without risking its life.
   • Limited Rejuvenation: Unlike many shrubs that can be hard-pruned for rejuvenation, old lavender has a limited capacity for this.

6. Eventual Decline and Death:

   • Due to the combination of woodiness, sparse growth, reduced flowering, and inability to regenerate effectively from hard pruning, older lavender plants will eventually decline and die out, often becoming unsightly in the process.

Management Strategy:

Instead of division, the longevity and vigor of a lavender plant are best maintained through:

• Annual Pruning: Regular, annual pruning (lightly shaping and removing spent flower stalks, and cutting back about 1/3 of the current year's growth) from a young age helps maintain a compact, bushy, and productive form, preventing excessive woodiness.
• Propagation by Cuttings: As the plant reaches 5-10 years of age (depending on species and conditions), it's a good practice to take cuttings from it. This ensures you have fresh, vigorous young plants ready to replace the aging parent when it eventually declines.

By understanding the natural life cycle and woody habit of lavender, gardeners can employ the correct strategies (pruning and cuttings) to enjoy healthy, productive plants for as long as possible before naturally replacing them.