GARDENING: Local lavender research presented at nat’l conference |

GARDENING: Local lavender research presented at nat’l conference

Curt Swift
Free Press Gardening Columnist
Properly covered lavender tucked in and ready for winter.
Submitted photo |

This past Saturday, Oct. 19, I had the opportunity to engage with other lavender growers, aromatherapists and researchers at the United States Lavender Growers Association Conference held in Richmond, Va.

Dr. Sean Westerveld with the Ontario Ministry of Agriculture and I had the responsibility to provide those in attendance with the research we have conducted on lavender over the last few years. Sean has been conducting research on lavender cultivars for Ontario growers to include winter hardiness, frost blankets to prevent winter and spring damage, and essential oil quality. It was interesting to learn his results for essential oil were the same Kathy Kimbrough and I have found with our recent research project.

Sean tested 26 cultivars of lavender and Lavandin; the Colorado trials tested 10. Neither of these projects were able to identify a lavender essential oil (e.o.) that matched what the International Stardards say they should be. E.O. of lavender is expected to contain 40 percent linalool and 42 percent linalyl acetate. This standardized oil should have the same aroma every time you purchase it. Such an oil obviously doesn’t exist in nature. Thus to achieve this level of aroma, linalool and/or linalyl acetate must be added to make the e.o. comply with the standard. Whether these volatile organic compounds are synthesized in a lab or somehow extracted from the other 100-plus compounds in lavender e.o. is a question one should ask when buying such a product. Even though the Canadian and Colorado research projects examined the e.o. of ‘Maillete,’ the cultivar used to develop the ISO French standard, our ‘Maillettes’ did not qualify as a 40/42 e.o.

Even though our area already has experienced a killing frost of 28 degrees F or below, lavender growers in this area are still working. Distillation of floral stems is continuing, bouquets have been shipped to consumers, and lotions, creams and other lavender value-added products are being formulated and packaged. The work seems to never end when you join the ranks of a lavender grower. The same thing is true with most farming activities. The work tends to swallow all your time and you don’t have any days off.

By the end of this week, should the weather hold up, the lavender I am responsible for will be watered and covered for the winter. I will be using Dewitt’s Ultimate Frost Blanket to completely cover these plants, some of which were planted within the last two weeks. This is Dewitt’s three ounce per square yard product that I found to be the most effective in protecting lavender from winter and early spring damage. Winter injury can be a serious problem for lavender growers.

Sean has found the same thing in Canada as I have; the frost blanket needs to be of sufficient thickness to prevent such damage. A lady from Vermont at the USLGA conference has been growing lavender since 1999 and covers her 4,000 plants with a frost blanket every year. She told me she has lost plants from old age, but never from winter injury. When new plants are covered this early, they will continue to grow, developing a more extensive root system. As the ground freezes, they will finally shut down for the winter. In the spring, plants covered with the proper weight of material look like they never experienced winter. Removing the blanket too early, however, before the spring frost season is over, can result in major plant damage. I’ll be removing the frost blankets in May 2014 and expect to find healthy plants already primed to flower.


Farmers will start burning field in the near future to prepare them for spring planting. They do this to rid the field of surface organic matter that would otherwise hamper furrow irrigation next year and to eliminate the costly process of plowing this material under. Burning their fields is an inexpensive method to prepare their fields for planting. It only gets costly when they burn down outbuildings or someone’s home, both of which tend to happen every few years.

Burning off matter results in an increase in atmospheric greenhouse gases as well as particulates and volatile organic compounds that pollute the air we breathe. If you were in the Grand Valley last winter, you know about the difficulty of breathing and associated health problems many of us suffered due to air pollution. Open burning was one of the causes of the poor air quality.

Wouldn’t it be great if there was a way farmers and others could rid their fields and farms of unwanted plant debris and at the same time produce a product that could be returned to the soil that has been shown to enhance plant growth, sequester carbon and reduce crop production costs? Next week I’ll discuss one way to accomplish that goal.

Dr. Curtis E. Swift is a retired horticulture agent with the Colorado State University Extension. Reach him at, 970-778-7866 or check out his blog at He owns Swift Horticultural Consulting and High Altitude Lavender.

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