GROWTH AND DEVELOPMENT OF HIPPEASTRUM GROWN IN GLASSHOUSES
The bulbs were planted on 4 dates distributed over the year. During the cropping period growth and development were evaluated at regular intervals. Leaf and bulb growth appeared to depend on the season. For the greater part of the year there was an increase in the leaf and bulb weight. During a short period in the late autumn and winter there was a cultivar-dependent decrease of leaf and bulb weight.
Bud initiation and growth did not depend on the season. During the short period of weight decrease bud initiation and growth continued. Development rate was therefore not determined by growth rate. Probably the temperature is the most important factor for the development rate. With increasing cropping period the number of aborted buds also increased.
Cv. 'Apple Blossom' was completely deciduous in winter, cv. 'Red Lion' only to a limited degree.
In cv. 'Apple Blossom' and 'Red Lion', once per 13 and per 11.5 weeks, respectively, 4 leaves and one bud were initiated. The initiation cycle was shorter than growing out to potentially flowering buds. Each 16 to 19 weeks one potentially flowering bud developed. Buds with a length of 20 mm at the moment of lifting the bulbs are a reliable indication of the flowering to be expected.
Growing Hippeastrum bulbs for flowering is possible in glasshouses in the Netherlands throughout the year. For the development of 2 flowering buds per bulb a growing period of at least 9 months is required, starting from plant material which is just not able to flower.