Detailed Guide to Periwinkle (Catharanthus roseus) Cutting Propagation Methods and Techniques

  For periwinkle cuttings, generally in spring or early summer, take softwood shoots 8-10 cm long, remove the lower leaves, keep 2-3 pairs of leaves at the tip, insert into a sand bed or leaf mold, keep the cutting medium slightly moist, at a room temperature of 20-24°C, roots will form 15-20 days after cutting.

  Cuttings are mostly taken from April to July. When propagating by cuttings, select vigorous, disease-free and pest-free softwood shoots from mature plants as cuttings; generally take 10-12 cm softwood shoots from the top of the plant, and the cutting length should preferably be 5-7 cm. Use a mixed medium of plain sand, vermiculite and peat as the cutting substrate, wrap a small ball of mud around the base of the cutting, insert it into a cold frame at a room temperature of 20-24°C, roots will form after about 20 days, and once the cuttings have rooted and survived they can be transplanted into pots. Because plants propagated from cuttings do not grow as vigorously as seed-grown seedlings, this method is rarely used in cultivation.

  Periwinkle seeds number between 700 and 750 per gram. Periwinkle is a perennial herbaceous plant and, under suitable conditions, can flower all year round. However, in the Yangtze River basin, because the climate is too cold, it is often grown as an annual, and sowing time is mainly concentrated from January to April. For sowing, a relatively loose artificial medium should be used; seedbeds or boxes can be used for raising seedlings, and where conditions permit, plug trays can be used. The medium requires a pH of 5.8-6.2 and an EC value of 0.5-0.75, and should be disinfected; after sowing, keep the medium temperature at around 22-25°C.

  [Seedling raising stages]

  Stage one:

  4-6 days after sowing, the radicle emerges. Initially keep the seedling medium moist, no fertilization is needed, and maintain the temperature at 25-26°C. Periwinkle seeds are light-avoiding (positive photoblastic negative) and germinate better under dark conditions, so they need to be lightly covered with coarse vermiculite or black film.

  Stage two:

  Keep the medium temperature at 22-24°C. As soon as the radicle emerges, moisture content must be controlled; watering after the medium has dried slightly can promote germination and control disease. At this stage, light must be increased so that the daily light period reaches 12-18 hours; the main root can grow to 1-2 cm, the cotyledons unfold, and the first true leaf appears. Keep the soil pH at 5.5-5.8 and EC below 0.75. After the cotyledons have fully unfolded, fertilization can begin, using 50-75 ppm of 14-0-14 and 20-10-20 water-soluble fertilizers, applied alternately every seven days. At this stage, after the seedling has pushed out of the medium and before the cotyledons have unfolded, special attention should be paid to maintaining air humidity, to avoid the seed coat failing to shed because the air is too dry; this is even more likely to occur when the temperature is relatively low. This stage lasts about 7-10 days.

  Stage three:

  Keep the medium temperature at 20-25°C; below this range, the chance of disease increases and growth slows. The medium should be kept alternately dry and moist, but plants must not wilt from lack of water. Periwinkle needs a warm and dry environment, which favors root development. Keep the soil pH at 5.5-5.8 and the EC value below 1. Fertilization can be applied alternately every 5-7 days with 100-150 ppm of 20-10-20 and 14-0-14 water-soluble fertilizers. This stage lasts about 14-21 days.

  Stage four (7 days):

  Keep the medium temperature at 18-20°C. Water only after the medium has properly dried out, apply 100-150 ppm of 14-0-14 water-soluble fertilizer, and increase ventilation to prevent leggy growth. This stage lasts about 7 days.