More information:

• New: Timing Tools for Hybrid Lilies
• PGR requirements for potted lilies
• Number of leaves per plant
• Cultivars and bulb sizes used in trials

Introduction and Problem: Height control is an ongoing issue for producers of pot lilies in North America. Our earlier work has indicated that pre-plant dips into growth regulator solutions are effective for height control. For example, Sumagic (uniconazol) in the 5-10 ppm range is effective and very cost-effective, although 10 ppm generally causes too much reduction for many cultivars. Bonzi or Piccolo (paclobutrazole) in the 100-200 ppm range is excellent for many cultivars, but somewhat more expensive than Sumagic. Ongoing work on rates (concentration) and cultivars is needed. Topflor (fluprimidol) is newly registered in the US, and has been very effective in earlier studies at Cornell.

Materials and Methods: Over 7-8 years, a number of cultivars have been trialed for response to pre-plant growth bulb dips. Typically, bulbs were dipped for 1 minute, and planted into 6" standard depth pots (MetroMix 360). Treatments varied by year, but typical treatments are given in the table below. Dipping and planting took place in late March to mid April, varying by year. Plants were forced in a 17C (63F) night temperature greenhouse with day temperature set to 17C, and were often higher as summer progressed. Standard fertilization, insect control (Marathon) and other cultural practices were followed. No fungicides were used.

Typical Treatments

• Control (water)
• 50 - 300 ppm Bonzi or Piccolo (paclobutrazole)
• 2.5 - 10 ppm Sumagic (unicolazol)
• 10 - 50 ppm Topflor (fluprimidol)
• 33 ppm A-Rest (ancymidol)