How fast does French lavender grow? The plant reaches full mature size in 2 to 3 growing seasons from a small nursery pot. Year one builds roots and shape. Year two fills in with heavy blooms. Year three brings the plant to its full spread of about 30 to 36 inches.
I tracked one plant from a 4-inch nursery pot in March to a full mound by the end of its third season. The plant hit 12 inches tall by October of year one. It reached 24 inches by the end of year two. By month 28, it stood at a full 2.5 ft (76 cm) tall and wide. The growth was steady but never flashy.
The french lavender growth rate follows a clear three-stage pattern. The first year is all about roots. The plant puts most of its energy into building a deep root system. You see only modest top growth above ground. The plant looks small but is building a strong base for the years to come.
Year two is when the show begins. The plant doubles in size and throws up heavy flower spikes. You get the full bloom display from May through October in mild zones. By the end of year two, the plant looks like a real shrub, not a young seedling. The growth feels fast at this stage.
Year One Root Building
- Top growth: Expect about 6 to 12 inches of height gain by the end of the first growing season. The plant looks small but is healthy if leaves stay gray-green.
- Root system: Most growth happens underground. Roots reach 18 to 24 inches deep in well-drained soil and set the stage for fast top growth in year two.
- Bloom count: You get a small first flush of flowers in summer, but skip heavy deadhead work this year to let the plant focus its energy on root growth instead.
Year Two Filling Out
- Top growth: The plant doubles in size to about 24 inches tall and wide by the end of the second growing season under good full-sun conditions.
- Bloom power: This is the first big flower year. Expect 3 to 4 full flushes between May and October with weekly deadhead work to keep blooms coming.
- Shape work: Do the first real spring prune in late February or March. Cut back one-third of the top growth to build a tight mounded shape for the future.
Year Three Mature Size
- Top growth: The plant reaches its full 30 to 36 inches (76 to 91 cm) in both height and spread by the end of the third growing season in ideal conditions.
- Bloom peak: This is the peak bloom year with the highest stem count and longest blooming season. Repeat-bloom cultivars can flower from April through October.
- Lifespan ahead: Past year three, the plant holds its size and bloom power for 5 to 8 more years with proper spring pruning before it gets too woody.
The lavender mature size varies by cultivar, so check the plant tag before you buy. Dwarf types like some 'Anouk' selections top out at 18 inches. Standard L. dentata reaches 3 ft (91 cm). Some L. stoechas hybrids stretch even taller in mild zones with rich growing seasons.
Want to push your lavender growing speed higher? Start with a bigger plant. A 1-gallon nursery pot beats a 4-inch starter by a full year. Plant in full sun with sharp drainage from day one. Skip the fertilizer, which only weakens the plant. Water deep but infrequent to push roots down.
I tested both starter sizes side by side in the same bed. The 1-gallon plant hit mature size in just 20 months. The 4-inch plant took the full 28 months to catch up. The extra ten bucks for the bigger pot saved me almost a year of waiting for full size and full blooms.
Be patient with year one. New growers often dig up a plant that looks small after one season, thinking it has failed. The plant is fine. It is just building roots that you cannot see. By year two and three you will get the full shrub you wanted, plus the bloom show that makes French lavender worth the wait.
Read the full article: French Lavender: Complete Grower Guide
