The Biologist Is In: Lavendar

Thursday, October 31, 2019

Lavendar

Botanical drawing of lavender plant, showing details of flower structure.

[From link.]

Lavender is a wonderfully aromatic plant with gorgeous flowers. When I moved to Minnesota I learned that most lavenders don't survive our winters well. There are a few varieties listed as surviving here, but they require "some winter protection".

I want lavender to grow and thrive here without care. This led me to start thinking about how I would go about breeding cold-hardy lavenders.

The first step with any breeding project is to figure out a plan. It can be a simple or complex plan, but something. Anyhow. I wanted to gather seeds from the most cold-hardy varieties available. But since I had never actually grown lavender before, I was hesitant to start with buying several relatively expensive plants that I might just kill the first winter.

While investigating the available varieties I realized the most cold-hardy ones were all from the species Lavandula angustifolia and that seeds for L. angustifolia were readily (and cheaply) available in any spring-time seed packet kiosk.

So, I picked up a few packets.

View into small square pot with dark soil and tiny green seedlings.

Lavender seedlings in pot.

This spring I scattered the -tiny- seeds on to the soil in a larger pot, pressed them in, and waited for something to happen. The seeds may have been old, or lavender may not be quick to start from seeds.

Eventually I had some little green seedlings that I didn't recognize growing in the pot. One day I was examining the plants closely, trying to figure out if they were stray weeds or not. To my surprise, I could smell lavender. Even the tiny seedlings are exuberant with their scent production.

Once the seedling had gotten a bit larger, I separated them out and transplanted each one to its own pot. I kept the pots where I could keep an eye on them and keep them watered. A few of the plants began to put on new growth, but most seemed to suffer and remain stunted. (In retrospect, I and our rains may have been keeping them too wet. Oh well, that just counts as a first selection pass. I don't want plants that have to be given special conditions, anyhow.)

Now that winter is coming on, I've brought the three best grown plants inside to overwinter under lights. I left the others to their fate outside in a cold-frame.

Since lavender varieties are propagated by cuttings, I could refer to these three plants as three new varieties. However, only time will tell if they're worth propagating. And really, I don't expect them to have the cold-hardiness that I'm looking for. The odds of one of these three meeting that criterion are astoundingly low.

Lavender #1.

Short lavender plant growing under lights.

Lavender #2.

Lavender #3.

I do like the dwarfed growth habit of the second plant. A closer look shows that it does have shorter internode distances than the other plants. It isn't just behind in its growth, it is actually growing differently.

Lavender #1, stem.

Close view of lavender stem tip on short plant.

Lavender #2, stem.

Lavender #3, stem.

I also like that it looks a bit more silvery than the other plants. A very close up view of some leaf tips shows that the second plant has much more prominent and branched trichomes. These photos were taken hand-held. I think I can probably do better and closer with some more technical preparation (tripod, lights, maybe focus stacking, etc.).

Extreme close up of lavender leaf tip, showing tiny branched trichomes on leaf surface.

Lavender #1, leaf tip.

Lavender #2, leaf tip.

Lavender #3, leaf tip.

What lessons have I learned and how do they impact my longer term goals?

Lavender varieties are propagated clonally, so there's no need for them to be homozygous for various alleles. As a result, lavender seeds would be expected to contain a surprising amount of genetic diversity compared to domesticated plants that are routinely grown from seed. The few plants I've grown have shown variations in ability to prosper in the temperature/water conditions I was growing them in, as well as having height and trichome differences.

I have no reason not to expect variations in cold hardiness will also be manifest when I grow out a larger population, though I don't expect one of these three to be a winner in that regard. I'm also looking forward to what other interesting traits may turn up.

The next steps are to acquire a larger number of seeds, grow more seedlings, then plant them out for winter. For initial hardiness trials, I can have many small plants in my back yard. If I find survivors, I'd want to collect seeds and begin the cycle again. Later I can plant seedlings or cuttings at a family property further north. Ideally, I would eventually find trial space in the far north of Minnesota, so the plants can be tested against the coldest that Minnesota winters can provide. That would be several years out, so I have some time yet to make arrangements if things develop such that they would be useful.

Why?

Funny you should ask. In the medium-term, I'm simply motivated by the desire to play around with the plant and produce something I can grow in my yard without having to spend too much effort at keeping it alive. In the long-term, I want to produce varieties that can be farmed for fragrance production in Minnesota. (All current lavender farms in USA are a few growing zones warmer than is available here.) This would open up a new crop for local agriculture and help to diversify what is grown in the state. I don't know if this will come to pass, but that's the thing about long-term goals.

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