Dahlia (tube-flowered dahlia subgroup) seed planting methods, troubleshooting for failure to bloom, and varieties

Dahlia is a perennial herbaceous plant. Dahlias are renowned for their many and varied flower colors and forms, rich and colorful, and are one of the world's famous flowers, cultivated in most countries around the world. So do you know what the methods for planting dahlia seeds are? What to do if they don't bloom? What varieties are there?

I. Dahlia seed planting methods

1. Pre-sowing preparation

(1) Sowing container

Choose a seedling tray 50 cm long, 20 cm wide, and 5 cm high. First rinse with clean water. Then disinfect with 0.2% chlorine-free nitrobenzene.

(2) Sowing substrate

Choose fine, uniform soil that is free of stones, free of pollution, rich in nutrients, and free of pests and diseases. Soil with good drainage and low salinity and alkalinity is preferable. The sowing substrate chosen is garden soil and peat. It is generally prepared by mixing garden soil, humus soil, and river sand in a ratio of 2:2:1, and disinfected with 2% quintozene or by high-temperature sterilization.

2. Sowing method

(1) Sowing time

Before sowing, wash the disinfected seedling tray clean with water. Sow immediately after the water has seeped in. For hotbed sowing, sow in mid-to-late March; for flowerbed varieties, sow in the open field in late April, scattering the seeds on the soil surface. After sowing large seeds, cover with moist fine soil, with a thickness of 3 times the seed diameter. After sowing, prop up agricultural film with bamboo poles, leaving gaps for ventilation, which helps raise soil temperature, reduce moisture loss, maintain soil humidity, and reduce soil compaction, thus maintaining the temperature and humidity needed for seed germination. After sowing, place at 20~25°C. About 7 days after sowing, the seeds will begin to germinate. Keep the soil moist at all times. When the seedlings grow to 4~5 cm, prick out the seedlings, water thoroughly, place in a shaded spot for 3~4 days, then move to strong light. Pay attention to watering in a timely manner to maintain soil moisture.

(2) Post-sowing management

Water according to soil moisture conditions. Keep the soil alternately dry and moist. When the soil surface is slightly dry, use the soak-watering method to keep it moist. The suitable temperature for seed germination is 19~21°C. Ventilate frequently after sowing, which is beneficial for seed germination. Dahlia seed germination requires appropriate shading. After the seedlings emerge evenly, gradually remove the film and move the seedlings to a spot with ample sunlight. Rotate the tray 180° every 2-3 days, which helps the seedlings grow upright.

II. What to do if dahlias don't bloom

1. Cause analysis

(1) Improper care

Factors such as sunlight, watering, and temperature may cause poor growth of dahlias. Insufficient sunlight or overwatering can cause the plant to grow leggy, producing only leaves and no flowers. Excessive fertilization or overly wet potting soil can cause poor root respiration, leading to root rot, which likewise affects flowering.

(2) Pest and disease infection

During the dahlia flowering period, that is, during flower bud differentiation, if the plant is disturbed by pests and diseases, the flower buds will have difficulty differentiating, and it will be difficult for flowers to bloom.

2. Solutions

(1) Increase light

Whether light is sufficient is key to growing dahlias. Insufficient light will cause branches to grow leggy and weak. Because the plant's internal nutrients are insufficient, it will not bloom or will bloom less.

(2) Increase fertilization

Before planting or before the plant sprouts, sufficient base fertilizer must be applied. If the base fertilizer is insufficient, the number of topdressings can be appropriately increased.

(3) Strengthen cold protection

In relatively cold regions, after winter begins, some dry grass, etc. should be spread on the ground, or the dahlia's tuberous roots should be dug out and dried, then stored indoors, and in the following year around Qingming, they can be planted in pots or in the ground.

III. What varieties of dahlia are there

There are many cultivated dahlia varieties, about 30,000 worldwide. By flower size, they are divided into three types: large-flowered (flower diameter above 20.3 cm), medium-flowered (flower diameter 10.1~20.3 cm), and small-flowered (flower diameter below 10.1 cm). By flower shape, they are divided into 11 flower types: sunflower type, orchid type, decorative type, ball type, fully open type, anemone type, bicolor type, peony type, cactus type, wavy-folded type, double-petaled type, double cosmos type, lotus type, and other flower types.

Its main cultivated varieties include:

Shouguang: The flower color is bright pink, with white petal tips. The flowers are gorgeous, with a flower diameter of 12 cm and a plant height of 110 cm. It is a summer and autumn cut flower variety.

Chaoying: The flower is bright yellow, with white petal tips, overlapping and round-thick, not revealing the flower center, with a flower diameter of 12 cm. Plant height 120 cm. Easy to cultivate.

Liren: The flower is purplish red, with white petal tips, with a flower diameter of 10 cm. Plant height 100 cm, with strong upright growth. It is a small cut flower variety.

Huazi: The flower is pure purple, with a flower diameter of 12 cm. The best variety among the purple series.

Ruibao: The flower is orange-red, not revealing the center, opening in a water lily shape, with a flower diameter of 12 cm. An extremely early-flowering variety. Suitable for greenhouse cultivation.

Fushou: The flower is bright red, with white markings at the petal tips.

Zhubao: Vermilion red in summer and autumn, turning orange-red after October, with a flower diameter of 12 cm.

Xinhuang: The flower is bright yellow, with white petal tips, and many flowers. Plant height 90 cm.

Hongfei: The flower is dark red, with upright leaves and many branches. Easy to cultivate.

Xinquan: The flower is bright red, with white petal edges, beautiful flower shape. An extremely early-flowering variety.

Hongzan: The flower is pink, with round petals, rose-shaped, with a flower diameter of 12 cm. The plant is compact and well-proportioned, very beautiful.