Controlling Flower Stalk Height in Lavender ‘Phenomenal’

In this video we evaluated plant growth regulators (PGRs), Dazide, Dazide/Citadel tank mix, Piccolo 10 XC and Concise for growth regulation of flower stalk growth in a new, vigorous lavender from Peace Tree Farm, the cultivar Phenomenal.

Liners were donated by Peace Tree Farm and planted in trade gallon plastic pots in August, bulked in the greenhouse until October and overwintered in a cold frame in Blacksburg VA. The PGR treatments were applied when flower stalks emerged in early May, as foliar spray applications at the label recommended volume. The Dazide treatment was re-applied at two weeks after the initial PGR applications.

We measured flower stalk height at 2, 4 and 6 weeks after treatment and noted the number of days to first open flower.

Lavender ‘Phenomenal’ was responsive to all the PGR treatments but the appearance and delay in flowering varied with the treatments. Dazide applications resulted in moderate control of flower stalk height but delayed flowering ~6 days. The tank mix of Dazide and Citadel gave less control with the same delay in flowering. Piccolo 10 XC resulted in light to moderate control with no delay in flowering while Concise gave excellent height control but delayed flowering up to 7 days.

Which PGR should you test? Watch the video and make your own decision!

Joyce Latimer is an Extension Specialist for Greenhouse Crops at Virginia Tech in Blacksburg, Virginia. Joyce has been evaluating plant growth regulators (PGRs) on herbaceous perennials for over 25 years. Her passion is improving plant quality and ease of production for producers while improving the quality of these plants for the home garden.