The prevention of “three-leaved plants” in the forcing of iris × hollandica by early heat treatment of stored bulbs or by ethephon field spraying

The number of non-flowering three-leaved plants occurring in the forcing of Iris ‘Wedgwood’ and Iris ‘Ideal’ can be drastically reduced if the bulbs are lifted several weeks before the normal lifting time and receive a 10-day 30°-treatment prior to the standard treatment for early flowering. The early lifting, however, leads to an appreciable reduction of the yield.An ethephon spray applied to the plants in the field several weeks before they die has a similar effect without the consequence of reduced yield because the bulbs can be lifted at normal time.