What causes blind stems and blind flowers in tulips?

Tulips are perennial bulbous herbaceous plants of the genus Tulipa in the lily family. They have an upright stature and large, colorful flowers, with high ornamental value. However, if not properly cared for, tulips are prone to blind stems and blind flowers.

The symptoms of blind flowers are as follows: the branches and leaves develop normally; in weak-growing plants, the flower buds dehydrate and appear white, pointed like a leaf tip, and the flower stem shrinks; in strong-growing plants, the flower stem is short, the petals remain green or white, and they curl together with the stamens and pistils, unable to open fully. Blind stems mean that the aboveground part of the plant produces only one oversized leaf, with no leafy branches, let alone flowering branches. The causes of their formation are as follows:

1. Related to variety, biological characteristics and cold treatment time: Because tulips were tempered by harsh natural conditions in their place of origin over a long period, they not only developed the varietal characteristic of being cold-tolerant but not heat-tolerant, but also acquired the biological characteristic of requiring a certain period of low-temperature treatment, with stems and leaves growing fully, before they can bloom. In the northern regions of our country, autumn and winter open-field planting can satisfy the low-temperature requirement, and they bloom from April to May the following year. Using this characteristic to subject tulip bulbs to 9°C or 5°C low-temperature treatment allows forcing cultivation and year-round flower supply. The blind flower phenomenon in production is mainly caused by bulbs not having undergone low-temperature vernalization or by too short a cold treatment time, so they have not reached the flowering requirement.

2. Related to bulb size and intermediate temperature: In production, bulbs of 12 cm or more are mostly used as planting bulbs; such bulbs have fully developed flower buds and mostly do not show blind flowers. Bulbs below 10 to 11 cm are mostly used for open-field planting, and after one year, once the flower buds have fully developed, they can also bloom normally; if used for forcing cultivation, the blind flower rate is relatively high. This is mainly because most of the flower buds of bulbs of this size have not yet fully developed, and before cold treatment they must be treated at an intermediate temperature of 17°C-20°C for 1-3 weeks longer than bulbs with a diameter of 12 cm. If bulb sizes are uneven, the intermediate temperature treatment is improper, and forcing cultivation is then carried out, and if fertilizer supply is insufficient during vegetative growth, blind stems and blind flowers are likely to appear. Therefore, producers are reminded that in large-scale production, bulb specifications should be strictly selected according to different cultivation methods.

3. The influence of human factors: First, when removing the bulb skin before planting, try not to damage the stem buds, so as to reduce the occurrence of blind stems. Second, extremely high temperatures caused by human factors during storage and transport, such as excessive heat released by the bulbs themselves or by other fruits, vegetables, flowers and engines, cause the production of ethylene within the bulbs. When the ethylene concentration reaches 0.1 dpm, it will cause the buds to die, and after planting, a large number of blind stems will appear.

4. The influence of other factors: For example, incorrect watering during cultivation, excessive humidity in the greenhouse, and diseased bulbs causing root asphyxiation mean there is even less yield to speak of.