Detailed Explanation of Hydrangea Cutting Propagation Methods and Technical Key Points

Although hydrangea has a long history of cultivation, it remains continuously popular. However, in recent years, due to aging varieties and serious illegal propagation, the prices of finished flowers have been relatively low. The breeding of new hydrangea varieties has also, to some extent, increased market demand and enhanced the competitiveness of growers. The upcoming months of March to May are the main planting period for hydrangea seedlings, in preparation for next year's New Year's Day and Spring Festival market. Below is a focused introduction to some management key points after the arrival of rootless hydrangea seedlings for New Year's Day marketing.

I. Preparation before arrival

1. Greenhouse conditions

Either a solar greenhouse or a modern glass greenhouse will do, but it must be equipped with fans, water curtains, heating and other temperature-raising and cooling facilities.

2. Plug trays

Use 50-cell or 35-cell plug trays.

3. Substrate

Generally, the growing medium is required to have good aeration, water-holding capacity and buffering capacity, and to be relatively stable. Substrate mixtures that do not contain peat or clay can all be used for production. The treatment with a perlite to humus soil mixing ratio of 1:2 produced the most robust seedlings. Red and pink varieties require a substrate pH of 5.5 to 6.0. Blue and white varieties are suitable for a pH of 3.5 to 4.0.

4. Water

Rainwater (or a mixture of tap water and rainwater) is the ideal irrigation water (pH around 7).

II. Cutting

It takes about 35 weeks for hydrangea to go from rootless seedling to market-ready. Finished plants for New Year's Day marketing need to be cut in late March or early April of the previous year. It is ideal for cuttings to root in seedling trays or individual seedling bags. But the key to success lies in the selection of the substrate; be sure to ensure that the selected substrate is not too hard, so as to facilitate rooting of the cuttings. Hydrangea is very sensitive during the rooting stage.

III. Rooting conditions

1. Temperature

During rooting, maintaining a temperature of 18°C to 20°C and a high-humidity environment is ideal, especially after cuttings are inserted. This is because if the substrate temperature is too high, root growth rate will slow down or even stop; while if the air temperature is too high, it will cause the plant stems to become thin and elongated and weak, and the root system may also stop growing accordingly.

2. Light and humidity

After cutting, appropriate shading and strengthened management are needed. Generally, the relative air humidity should be 80% to 90%. When the seedlings have grown for 20 to 25 days and the root system has filled the nutrient pots or plug trays, they can be potted up.