Few plants can match the all-around versatility of lavender. Full in flower, beautiful in form, fragrant, long-lasting, bee-friendly, deer resistant and drought tolerant, it is high on my list of desirable landscape plants. Yet in many part of the United State lavender is hard to obtain. You can order it mail order or you can grow it yourself. Growing it from seed is notoriously difficult – if you can find the seeds. The variety I prize most highly, Lavender intermedia, also known as “Provence” is not available by seed. If you want to grow it you need to learn how to propagate it by taking cuttings. That’s what we’re going to examine in this blog.
Timing is Important
In Northern California lavender grows actively during the six warmest months of the year, April through September. It is green (blue-grey, actually) year ‘round, but this is deceptive because during the coldest months of the year with the shortest daylight hours, lavender is essentially dormant. Cutting season is right now, during the period of active growth because this is when it forms roots most readily and growing conditions are best. You might be able to take cuttings as early as April, but this would deprive you of the flowers which bloom in late spring and early summer. We wait until now, mid-summer, when the blooms have past their prime, to take our cuttings. Note that it’s best not to wait too long after the flowers begin to decline, because it can take 6-8 weeks for lavender to root well enough to transplant, and by then the days are growing shorter and cooler.
Where to Cut
Remove the flower spikes to get to the leaf clusters, as pieces of the leaf clusters are your cutting material. Depending on how many lavender plants you have, and therefore how much cutting material you have available, you may take longer or shorter sections of the leaf clusters. The bare minimum is two nodes, one node to root in your medium and one to remain above. This meager amount doesn’t always generate the best results, as the resulting rooted cuttings have very little foliage and take considerable time to develop. Better, if you have enough material to take four nodes total, two for rooting and two for foliage growth above the growing medium.In the image to the right, a bunch of cuttings with stalks still attached.
When choosing your cutting material, choose the soft, new growth, not the hard growth from previous years. After taking your cutting, cleanly remove the leaves to where they join the stem using sharp scissors. Scissors with a needle tip are great for this task. You want the node exposed to your growing medium and moisture to encourage root growth.
In the image to the right, a fresh cutting, flower stalk removed. Note the bottom set of leaves has also been removed to aid rooting.
Healing the Cut
At this stage of the process your lavender cuttings are vulnerable to drying out and dying: they have a lot of leaf area and no roots whatsoever, just an open wound where you exposed the nodes. To prevent loss of your fresh cuttings you need to plunge them immediately into a moist medium where the lower nodes stay wet at all times. We carry a tray at our side filled with damp vermiculite about 2” deep (note: the tray drains at the bottom to prevent too much saturation of the cuttings which would cause them to suffocate and rot from lack of oxygen). After filling our tray with cuttings we move it to a bench with a wire surface beneath shade clothe where it receives regular overhead watering throughout the day.
Lavender requires good air circulation for optimum growth. We have learned from experience that storing our cuttings in a greenhouse risks loss due to rotting because of the high moisture level in the greenhouse. This is another good reason to find a shady outside location to heal your cuttings.
About three weeks after taking your cuttings, test them to see if they are developing roots at their base. A simple, gentle tug on the cutting will tell you what you need to know. If the cutting is taking root it will resist the tug because new roots are holding the growing medium. If it pulls free it may be slow to root or not rooting at all. White roots are a sign that all is well. A brown lower stem is a sign that your cutting is failing.
Moving Your Cutting to Soil
After your cuttings have well developed roots, about 1” long, it is time to move them to soil. The pots containing the soil don’t need to be large. We use square transplant pots 2-1/2” in diameter. We use a standard transplant mix composed of 1/3 peat, 1/3 perlite and 1/3 compost. We fill a tray with the pots, moisten the soil well, and begin transplanting, gently removing the cuttings from their medium and transferring to the pots. Sometimes the medium clings to the roots. If you can’t remove all of it don’t worry, it is better not to damage th
e roots than to have them thoroughly cleaned of the rooting medium.
After transplanting we water the immature plants well, one more time. Then we return them to the shady outdoor area with good air circulation. At this stage in the process water management is of critical importance. Too little water and the roots don’t grow into the surrounding soil. Too much water and the plants will rot. A sure sign of rot is blackened leaves at the base of the transplant, or even worse, a blackened stem at the base where it meets the soil. When you see that you need to scale back your watering. In general, the best approach is to let the soil dry between watering, which means you may water every other day or every third day. Pay close attention during this stage of the process!
Transplanting into the Garden
Once the lavender has developed enough roots to bind together the soil in the pot, it is time to move it into your garden or landscape. Ideal locations for lavender have excellent drainage, full exposure to sun, and good air circulation. Late summer and early fall are ideal for transplanting lavender in locations with moderate winter temperatures. The gentle, gradual cooling of the air as the days slip into fall put less stress on the new plantings. When late fall rains arrive they have had time to settle in; the rains help them extend their roots further, establishing a good base for spring grow
th. Early to mid-spring is better in areas with severe winters. If you’re in a marginal area, planting on the sunny side of a south-facing wall that will absorb heat and protect from excessive exposure to wind can improve the plants’ chances of success. Best of all, when you find the right spot, you’ll find that your lavender returns and looks glorious year after year with almost no effort whatsoever.
The apex of tomato growing season is just weeks away. Wherever you live, let us know about your first ripe tomato. Here’s a link to a section of our website where we post our customers’ success stories.
I’ll be traveling in England the next three weeks. Who knows what interesting garden-related experience I might have in a land where the interest in gardening is legendary.
Check back in August, when we'll look at another hands-on gardening project.