Many people who visit Monte-Bellaria say that they’ve had problems growing lavender for the long run. We’ve heard folks say that they’ve had beautiful growth for several years with large blooms, and then the plant seems to simply die.
The usual problem they describe is that the plant starts getting “bald spots,” and that is—in fact—usually a pre-cursor to early death (the plant dies from the inside out). This is referred to as “mid-center death.”
However with proper care and trimming, lavender (both English and Lavendin hybrids—Grosso, Provence, etc.) can live up to 15 years. Some gardeners have even documented plants that live up to 24 years!
We’ll assume that you are starting with healthy, disease-free plants. Look carefully at the plant you are buying to make sure it is not withered, yellowed or rangy.
So let’s start with the location that will be ideal for a long-term healthy lavender plant. The first dimension is sunlight. FULL sun is really the best advice for lavender planting. Lavenders love heat, light and semi-dry conditions. When planted in shade, the growth will be lop-sided with blooms favoring the bright side.
Related to too little sun, is too much water. Lavenders hate wet feet. Planting in shade keeps too much moisture in the soil and is a breeding ground for the only serious disease that affects most lavenders—a proto-mold called Phytophthora (spread by water-borne oomycetes) which results in “root and crown” rot. Some nursery sources attempt to treat young plants with fungicides which will prevent some root related diseases, but not Phytophtora.
Some lavenders (and in specific Grosso and Provence lavendins) have shown to be semi-resistant to Phytophthora…but water will still kill by destroying the roots.
The soil for the planting site should be sandy, with little to no clay. Clay creates what is referred to as a “pot hole,” an impermeable barrier that holds water like a bowl under the plant. If you have clay, make sure you are digging a hole at least two feet deep and wide, and amend the soil with sandy loam.
Trimming is also very important for long-run health. The full blooming lavender will have large spikes that extend well beyond the central plant.
These need to be trimmed back to create a dome shape that is tight to the central plant. This is best done at the end of the season in late fall but definitely before winter. At Monte-Bellaria (Northern California) we trim in early November.
In some cases, lavenders that are harvested early for dried flowers (May or June) will have a second bloom growth, but this is usually much less dense than the initial bloom.