Yes, the scent strength of a lavender variety absolutely affects its pest-repelling abilities. This is directly related to the concentration of the key aromatic compounds within the plant's essential oil.
As discussed, the primary compounds in lavender responsible for deterring insects are linalool and linalyl acetate. Some varieties also contain camphor, which contributes to the repellent effect.
Here's how scent strength and chemical composition relate to pest repellency:
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Higher Concentration = Stronger Repellency: Generally, lavender varieties (or essential oils derived from them) that have a higher concentration of these repellent compounds will exhibit a stronger and more effective deterrent effect. A more pungent or intensely scented lavender will likely have more of these volatile molecules diffusing into the air.
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Variety Differences: Different species and cultivars (varieties) of lavender naturally produce varying amounts of these compounds.
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English Lavender (Lavandula angustifolia): This is known for its sweet, floral scent and is often prized for its high content of linalool and linalyl acetate, with low camphor. Many popular cultivars like 'Munstead' and 'Hidcote' fall into this category. While they have a lovely scent, their repellent power for certain pests might be slightly less than some hybrids due to lower camphor.
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Lavandin (Lavandula x intermedia): This is a hybrid cross between English lavender and Spike lavender (Lavandula latifolia). Varieties like 'Grosso' or 'Provence' are known for their very strong, often more camphoraceous (medicinal) scent. Lavandins typically have a higher yield of essential oil and often contain higher levels of camphor in addition to linalool and linalyl acetate. This higher camphor content can make them particularly effective at deterring insects that dislike that sharper aroma, such as some mosquitoes and moths. Due to their robust growth and strong scent, lavandins are often preferred for pest control purposes in larger garden areas or for making deterrent sachets.
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Spike Lavender (Lavandula latifolia): This species naturally contains higher levels of camphor and 1,8-cineole (eucalyptol), giving it a very strong, somewhat medicinal scent. While less common for fragrance in perfumery, its higher repellent compound content could make it quite effective against pests.
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Essential Oil vs. Plant: It's also worth reiterating that lavender essential oil (which is a concentrated extract of these compounds) will almost always have a much stronger and more immediate repellent effect than a live plant in the garden, regardless of the plant's scent strength. The efficacy of a live plant depends on the number of plants, their size, and how much their foliage is disturbed to release the scent.
In summary: If your primary goal is pest deterrence, choosing lavender varieties that are known for their strong scent and higher concentrations of compounds like linalool, linalyl acetate, and (if desired) camphor would be beneficial. Lavandins like 'Grosso' are often good choices for their potent aroma and robust growth, making them effective garden deterrents.
