Different lavender varieties can and do cross-pollinate in Wisconsin. The principles of cross-pollination remain the same regardless of climate, as long as the plants are flowering and pollinators are active.
Here's why and what it means for Wisconsin gardeners:
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Pollinator Activity in Wisconsin: Wisconsin has a diverse population of pollinators, including many species of bees (around 400 verified species!), butterflies, and other insects. When lavender plants are in bloom during Wisconsin's growing season (typically late spring through summer, depending on the variety), these pollinators will readily visit the flowers and transfer pollen between different lavender plants.
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Cold-Hardy Lavender Varieties: Many English lavender varieties (Lavandula angustifolia cultivars like 'Munstead' and 'Hidcote') and some Lavandin hybrids (Lavandula x intermedia like 'Phenomenal') are hardy enough to survive Wisconsin winters (USDA Zones generally 4-5, with proper care). These varieties flower reliably in Wisconsin summers.
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Genetic Mixing in Seeds: If you have different varieties of lavender blooming simultaneously in your Wisconsin garden, bees will carry pollen from one to another. If you then collect and plant seeds from these plants, the resulting offspring will be a genetic mix. This means:
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They will not be "true to type" – they won't look or smell exactly like the parent plant you collected the seeds from.
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You might get interesting, unique variations in flower color, plant size, bloom time, and scent. This can be a fun experiment for a hobby gardener.
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Propagation by Cuttings for Consistency: Because of this cross-pollination, if you want to grow a specific lavender variety that is genetically identical to its parent (e.g., to expand a patch of 'Munstead' lavender), you should propagate it from cuttings rather than from seeds. Cuttings are clones and will retain all the characteristics of the original plant. Many commercial lavender growers in Wisconsin and other cold climates use cuttings for this reason to ensure uniformity in their fields.
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Impact on Essential Oil: For commercial lavender farms in Wisconsin (which do exist!), cross-pollination can increase the overall yield of flowers and thus essential oil. However, if they are aiming for a very specific essential oil chemical profile (e.g., the high linalool/linalyl acetate content prized in pure English lavender essential oil), they will still need to manage their fields carefully, often relying on propagation from cuttings of genetically pure stock to ensure consistency in their product.
In short, if your lavender varieties are happy enough to bloom in Wisconsin, they are happy enough to cross-pollinate with the help of the local bee population!
