In this section, you will find the growing methods in use, the growing techniques, crop protection, disease control and variety choice of tulips, hyacinths and narcissus.

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12.2 Production methods The production methods for 9°C and uncooled tulips are almost identical to that of 5°C tulips. However, the following points must be made. Plant as soon as the soil temperature in the greenhouse has fallen to 9°C or less. Depending on the climate and measures taken to lower the temperatures, this is usual-ly reached mid-Novem-ber. However, if the soil temperature is still too high, do no plant the bulbs, but continue to provide the dry bulb cold treatment. To avoid rooting problems and poo-rer quality, do not plant after 15 December. To prevent the bulbs from pushing their way up through the soil and to ensure an even soil temperature, apply a layer of 1 to 2 cm of soil over the noses of the tulips. The bulbs do not need to be stripped. Bulb size 11/12 is highly suitable for this method. After the bulbs have received the necessary cool -treatment, the greenhouse temperature at crop height must be maintained at appr. 18°C. The number of days in the greenhouse (from the end of the cold phase until the end of harvest) depends on a number of factors and varies from 20 to 40 days. The number of greenhouse days must be increased by some 10-20% for the cultivation of 9°C and uncooled tulips in the border soil of the greenhouse.