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Sticking Lavender in the Greenhouse

Lavender cuttings can make a dramatic display.

One of the most effective ways to generate a multitude of plants is to grow your own from cuttings that will get a good start in the greenhouse. This month, Iā€™m talking with Nancy Connolly Blum, a professional landscape gardener and former owner of the Sawmill Ballroom Lavender Farm in Oregon. Here are the propagation steps she learned when she was a lavender purveyor. ā€œI was always trying to figure out the easiest way to do it,ā€ she says. ā€œIt is an enjoyable task that will likely produce success.ā€

Lavender cuttings root easily.
Lavender in quantity can be made from cuttings.

Cut in Spring or Fall

Taking cuttings encourages lavender to bulk up. The timing in spring? ā€œWhen the trilliums bloom,ā€ Nancy says. If you have no trilliums in your part of the U.S., observe the plants themselves. They should have started to put on some new growth above where last yearā€™s growth ended. That new growth is what will root best.

Lavender is a major player in this Mediterranean-style garden.

You can also clip fall cuttings around Labor Day, which in most parts of the country will give the plants time to root and establish before growth slows in the late fall. Itā€™s possible to overwinter in a bright cool greenhouse.

New roots will form along the leaf nodes.
New roots will form along the leaf nodes.

The cuttings can be approximately three or four inches long, taken with sharp snips. You can also use the snips for removing the lower leaves or you can pinch out the leaves with your fingernails. The cells in each leaf node will make the roots. No rooting hormone is needed.

Seventy-two count cell packs will garner many future plants. (courtesy Nancy Connelly Blum)
Seventy-two count cell packs will garner many future plants. (courtesy Nancy Connelly Blum).
Small cell packs are a great starting point for cuttings. (Courtesy Nancy Connolly Blum)
Small cell packs are a great starting point for cuttings. (Courtesy Nancy Connolly Blum).

Prevent Drying Out

This is the one point in this process that is critical. The cuttings and their incipient root nodes must not dry out. So, prepare the pots to receive the cuttings before you snip. Containers can be cell packsā€”fifty count is good, Nancy saysā€”or flats, or old six-packs reused. Any good free-draining potting soil will work. Water the containers beforehand.

Stick lavender cutting in soil to the lower leaves.
Stick lavender cutting in soil to the lower leaves.

Take three or four cuttings at a time, and gently push them into the soil up to the existing leavesā€”thatā€™s called sticking. If they are too tender, they may break off. Discard those and try again, taking a snip a little further down the stem into the older growth for sturdiness. More practice with your particular plantā€™s growth pattern allows you to learn what is required.

Take springtime lavender cuttings when trilliums bloom.
Take springtime lavender cuttings when trilliums bloom.

No need to cover the cuttings. They may wilt a bit. Place in a cool sheltered location away from heat and sun for two or three days until they regain their upright stance. Then, for optimum growth, place the cuttings on a heat mat under grow lightsā€”follow manufacturersā€™ instructionsā€”in soil that ranges around 50-60 degrees F. ā€œChecking with a thermometer tells you,ā€ Nancy says, ā€œthat the mat is not malfunctioning.ā€

These cuttings are ready for sticking.
These cuttings are ready for sticking.

Keep the cuttings evenly moist. When the top of the soil is dry, Nancy suggests resting the containers in a shallow dish with a half-inch of water. Allow the water to wick up from the bottom, then put the containers back on the mat. They will be heavier when soaked.

A variety of containers can receive cuttings.
Cuttings will form roots in four to six weeks.

Pot Up When Needed

Roots appear in approximately four to six weeks, depending on conditions. A well-rooted plant holds the surrounding soil together. Then the cuttings can be taken off the heat mat and potted up to bigger containers or even moved to the garden. If roots push out the bottom, thatā€™s a definite signal to repot immediately.

Bright green indicates new growth on this lavender.
Bright green indicates new growth on this lavender.

This process can be successful for many kinds of plants. ā€œItā€™s not hard. If it doesnā€™t work, try again,ā€ Nancy says. ā€œAnd experiment. Take what I do and manipulate it to your style. Maybe youā€™ll find a better way.ā€

 

Cuttings can be taken from lavender in spring and fall.
Cuttings can be taken from lavender in spring and fall.