Tungsten lamps have traditionally been used because they are cheap and have a suitable light quality.
However, Defra announced that "inefficient" tungsten lamps will be phased out from January 2008 to December 2011. Furthermore, some growers want to move away from tungsten lamps to minimise stretching. Consequently, the suitability of alternative lamps needs to be assessed.
Perhaps the most obvious alternative, at least in the short term, is compact fluorescent lamps. However, these have a different light spectrum.
HDC project PC 296 was designed to examine the suitability of energy-saving lamps for day-length control by investigating flowering responses to light quality and quantity. The first part of the project compared tungsten and compact fluorescent lamps.
Results have shown that compact fluorescent lamps can be safely used for chrysanthemums, poinsettias, fuchsias and begonias. However, with other plant species tested a more cautious approach should be adopted because they responded to the fluorescent lamps in different ways to the tungsten lamps.
Growers are advised, if replacing tungsten bulbs, to test the most favourable alternative compact fluorescent strategies on a small scale with their own mix of plant varieties before implementing changes.
Date for your diary
Hardy Nursery Stock Panel Meeting, Stoneleigh, Warwickshire, 15 December.
Horticultural Development Company
For details on all HDC activity, visit www.hdc.org.uk