What is cross-pollination in the context of lavender?

In the context of lavender, cross-pollination refers to the transfer of pollen from the flower of one lavender plant to the flower of a different lavender plant. This "different" plant could be a different variety of the same species (e.g., 'Munstead' English lavender to 'Hidcote' English lavender) or, more significantly, a different species altogether (e.g., English lavender to Spike lavender).

Here's a breakdown of what that means for lavender:

1. How it Happens:

   • Pollinators: Lavender flowers are highly attractive to bees (honeybees, bumblebees, and various native bees), butterflies, and other insects. These pollinators are the primary agents of cross-pollination. As they forage for nectar and pollen, they inadvertently pick up pollen from one flower and deposit it on the stigma of another.

   • Simultaneous Blooming: For cross-pollination to occur, the two different lavender plants must be flowering at roughly the same time. Different lavender species and even varieties have different peak bloom periods, but there's often overlap, especially if you have a diverse collection.

   • Proximity: While pollen can travel, cross-pollination is more likely and efficient when the different lavender plants are in close proximity to each other in a garden or field.

2. Implications for Seeds and Offspring:

   • Genetic Mixing: When cross-pollination occurs, the seeds produced by the recipient flower will contain genetic material from both parent plants (the plant that provided the pollen and the plant that received it).

   • Not "True to Type": This is the most important point for gardeners. If you collect seeds from a lavender plant that has been cross-pollinated, the offspring grown from those seeds will not be identical to the parent plant. They will be hybrids with a mix of characteristics from both parents.

   • Variability: These hybrid seedlings can show a wide range of traits:

     • Different flower colors (e.g., lighter or darker shades of purple, or even white/pink in rare cases).

     • Varying plant sizes and growth habits (taller, shorter, more sprawling, more compact).

     • Different bloom times.

     • Subtly different scent profiles (e.g., higher or lower levels of specific aromatic compounds like linalool or camphor).

     • Differing vigor or disease resistance.

   • New Hybrids: This is how new lavender varieties (especially hybrid types like Lavandins, Lavandula x intermedia) naturally occur. Lavandin, for instance, is a natural hybrid between English lavender (L. angustifolia) and Spike lavender (L. latifolia) that occurred when these two species grew near each other and were cross-pollinated. Plant breeders also intentionally facilitate cross-pollination to create new cultivars with desirable traits.

3. Propagation for Consistency:

   • Because seeds from cross-pollinated plants produce variable offspring, most named lavender varieties (cultivars) are propagated vegetatively, typically by cuttings.

   • Cuttings are Clones: A plant grown from a cutting is a genetic clone of the parent plant, ensuring it retains all the exact characteristics (flower color, scent, size, hardiness) of the original. This is why commercial growers and even many home gardeners rely on cuttings to maintain specific lavender types.

4. Impact on Essential Oil Production:

   • Yield: Cross-pollination by bees is generally beneficial for essential oil yield. Pollinated lavender plants tend to produce more flowers and seeds, which can lead to a higher overall quantity of essential oil compared to plants that are not pollinated.

   • Quality (Chemical Profile): This is where it gets more complex. While cross-pollination can increase yield, it can also subtly alter the chemical composition of the essential oil. For commercial growers aiming for a specific, consistent essential oil profile (e.g., true Lavandula angustifolia oil prized for high linalool and linalyl acetate, and low camphor), maintaining genetic purity through vegetative propagation and sometimes isolating fields is crucial to avoid unwanted changes in the oil's chemical makeup. Lavandin essential oil, for example, naturally has a higher camphor content than pure English lavender oil because of its hybrid parentage.

In summary, cross-pollination in lavender is the transfer of pollen between different lavender plants (varieties or species), primarily by insects. Its main consequence for gardeners is that seeds collected from such plants will produce offspring with mixed, unpredictable characteristics, unlike plants grown from cuttings which are genetic copies of the parent.

Lavender Farm in Door County Wisconsin. You can buy lavender products online at islandlavender.com