Detailed Explanation of the Planting Methods and Technical Key Points for Roselle
Roselle is Hibiscus sabdariffa, and the seed of the mallow family plant Hibiscus sabdariffa. The calyx is purplish red to purplish black, five-lobed, with lanceolate lobes; at the lower part, small bracts fused with the calyx can be seen, about ten in number, lanceolate, with a cavity left at the base after the fruit is removed. The corolla is yellow-brown, with linear stripes on the outer surface and a yellow-brown base on the inner surface, occasionally with sparse coarse hairs. Light in weight and brittle in texture. Slight delicate fragrance, sour taste.
Cultivation Methods for Roselle
1. Soil requirements: Roselle is a plant that fears waterlogging but not drought, and is suitable for planting in sunny, deep sandy loam soil with good drainage.
2. Sowing time: Soak the seeds for 12 hours before sowing; sowing from mid-to-late April to early May is more suitable, with 3-4 seeds per hole for dibbling; for seedling raising and transplanting, transplant promptly when the seedlings are 15 cm tall.
3. Water and fertilizer management: Roselle does not need large amounts of water and fertilizer, but for land with poor fertility and poor seedling growth, appropriate additional fertilizer should be applied; apply 20 kg of compound fertilizer and 8 kg of urea per mu to promote seedling growth; before flowering, apply 30 kg of compound fertilizer and 20 kg of potassium sulfate per mu to meet the needs of flowering.
4. Seedling stage treatment: When the seedlings grow to 10-15 cm, thinning should be carried out, removing weak and diseased seedlings, leaving only one healthy seedling per hole, and the rest should be pulled out to fill gaps; thinning should not be too late, otherwise it will affect seedling growth. When the seedlings are 80 cm tall, pinching should be carried out to promote strong branches, more flowers, and plump calyces.
5. Cultivation and weeding: When the plants are 30 cm tall, combine with topdressing and earthing up, and carry out 2-3 cultivations at the appropriate time. In summer, weeds should be removed by hand, and in the rainy season, ditches should be dug for drainage to prevent seedling death and the occurrence of root rot.
6. Pest and disease control: Roselle has relatively strong insect resistance, and generally there are few pests and diseases. To be safe, after sowing and emergence in 5-7 days, spray with 2.5% lambda-cyhalothrin 50 ml per mu to control pests.
Precautions for Cultivating Roselle
Control of root and crown rot: When it occurs, use 5 g of 5% Baodingning and 30 ml of 2% kasugamycin mixed with 15 kg of water to drench the roots twice.
Pesticides must be sprayed before flowering; spraying pesticides is strictly prohibited during the flowering period, so as to avoid pesticide residues remaining in the calyx and affecting product quality.