Experience sharing on forcing cultivation of tulips to bloom during Spring Festival

Tulips have strong cold resistance, tolerating low temperatures of -35°C in winter, and can grow normally at 5°C-8°C, making them suitable for winter forcing cultivation.

Forcing cultivation of tulips means breaking the dormancy of flower primordia and leaf primordia through variable temperature treatment of the bulbs, eliminating factors that inhibit flower bud germination, and promoting flower bud differentiation, then through artificial heating, supplemental lighting and other measures, making tulips bloom outside their natural flowering period. Currently on the market there are commonly 5°C bulbs and 9°C bulbs; we generally choose 5°C bulbs for forcing cultivation to bloom during Spring Festival.

Substrate preparation

First, prepare a high-quality substrate that is both water-retentive and air-permeable, with salinity not too high and not too acidic; the pH value should be no less than 6, with no pests, diseases or harmful substances. The bulbs should be planted very firmly in a sufficiently deep (at least 5cm deep) cultivation bed. In recent years we have used peat, decomposed soil and sand mixed at 1:1:1 as the cultivation substrate, with good results. About half a month before planting, apply decomposed farmyard manure into the bed soil as base fertilizer, and add an appropriate amount of carbofuran and carbendazim (or irrigate and cover with 1% formalin for disinfection), water thoroughly, and carefully plow and harrow before planting to ensure the soil is loose.

Planting

Because the soil temperature inside the greenhouse is high, tulips will undergo late vernalization, and the low-temperature treatment effect of forcing cultivation will be reduced. Therefore, early planting is not as good as late planting; generally plant about two months before Spring Festival, around early to mid-November. Before planting, remove the brown bulb skin, and soak in a 500-fold dilution of 50% carbendazim for about two hours. The plant and row spacing is 9×10cm; when planting, the top of the bulb should be level with or slightly below the soil surface. Properly shallow planting can advance flowering; sometimes when the tulip bulb is about 1/3 exposed above the soil surface, flowering can be advanced by more than 5 days. After planting, water thoroughly to promote rooting.

Cultivation management

Temperature: Generally after one week, the bulbs begin to sprout. Before and during the seedling stage, keep the indoor temperature at 12°C-15°C during the day; if the temperature is too high, ventilate promptly to cool it down; at night it should not be lower than 6°C, to promote early rooting and strong roots of the bulbs and cultivate strong seedlings. If the temperature is too high at this time, the plant stems will be weak and flower quality poor. After more than 20 days, when the plant has grown two leaves, increase the temperature promptly to promote the flower buds to break free from the bracts in time. Keep the indoor temperature at 18°C-25°C during the day and above 10°C at night. Generally after another 20-plus days, the flower crown begins to color; the first flower opens from late December to early January, and full bloom takes 10-15 days. At this time, place them in batches according to the different times flowers are needed; the higher the temperature, the earlier the flowering. Generally, after the flower crown is fully colored, the plants should be placed in a 10°C environment for sale.

Light: Sufficient light is essential for tulip growth. Insufficient light will cause poor plant growth, bud drop, weak plants, lighter leaf color and shortened flowering period. However, within more than half a month after potting, tulips should be properly shaded to help the bulbs grow new roots. In addition, during germination, the elongation of flower buds is inhibited by light; after shading, the elongation of flower buds can be promoted, preventing excessive vegetative growth and spindly growth in the early stage. After emergence, light should be increased to promote stem elongation, flower bud formation and coloring. In the later stage, after the flower buds are fully colored, direct sunlight should be prevented to prolong the flowering time.

Fertilization: Because the substrate is rich in organic fertilizer, no additional fertilization is needed during the growth period. However, if nitrogen is insufficient and the leaf color becomes lighter or the plants do not grow stout enough, nitrogen fertilizers that are easily absorbed such as urea and ammonium nitrate can be applied, but the amount must not be too much, otherwise it will cause spindly growth and may even affect the plant's iron absorption and cause iron deficiency (when iron is deficient, new leaves and flower buds all turn yellow, but old leaves remain normal). Applying liquid fertilizer during the growth period has a significant effect. Generally, from bud appearance to flowering, spray a 2‰-3‰ concentration potassium dihydrogen phosphate solution once every 10 days to promote large flowers with vivid color and sturdy, upright flower stems.

Water: After planting, water thoroughly so that the soil and bulbs can fully and closely combine to facilitate rooting. After sprouting, water should be properly controlled. When the leaves gradually elongate, water can be sprayed on the leaf surface to increase air humidity. During the flower stem elongation stage and bud appearance stage, ensure sufficient water supply to promote full flower development. After flowering, properly control water.

Pest and disease control: The pathogenic bacteria of tulip pests and diseases can be carried by the bulbs, or the bulbs can be infected by soil-borne pathogens. They mostly occur in high-temperature and high-humidity environments. The main diseases include stem rot, soft rot, color-breaking disease, damping-off, and blind buds, while the main pest is aphids.

Control methods: Perform thorough soil disinfection before planting, use virus-free bulbs for cultivation as much as possible, promptly dig out and destroy diseased plants, and apply fungicide 1-2 times during greenhouse growth for better results; maintain good ventilation to prevent high temperature and high humidity; when aphids occur, spray with a 800-fold dilution of 3% natural pyrethrin.

Others

1. Potted tulips managed directly after potting: because bulb quality varies, growth and flowering are uneven, affecting their commercial quality. Therefore, it is best to first plant them in the ground inside the greenhouse, and after the flower crowns are colored, transfer them to pots for management; this does not affect their flowering quality and gives better results.

2. Among flower colors, red blooms earliest and yellow latest, roughly about 10 days apart. During cultivation, planting times should be properly staggered to ensure simultaneous flowering.