Detailed Explanation of Lavender Propagation Methods and Cultivation Techniques

Lavender originated in the Mediterranean region and belongs to the genus Lavandula in the family Lamiaceae. It is a perennial subshrub. Leaf shape varies by variety. The inflorescence is a spike-like verticillaster, with colors ranging from deep purple to peach red, though some varieties are white. The entire plant has a fragrant aroma. After years of introduction and research, we believe that Hokkaido lavender has extremely high ornamental value and is a good variety for modern agricultural tourism. Its propagation and cultivation techniques are introduced as follows.

I. Morphological Characteristics and Growth Habits

Hokkaido lavender is a well-known herbaceous plant, with a plant height of 20-100 cm, alternate leaves, elliptical lanceolate leaves, spike-like inflorescences, and blue-purple, richly fragrant flowers. It is known as the "tranquil perfume plant," with a flowering period from May to October. Lavender has low soil requirements, prefers sunlight, is cold-tolerant, drought-tolerant, barren-tolerant, and resistant to salinity and alkalinity, but not tolerant of high temperatures and humidity. It can grow at 5-30°C, but when summer temperatures remain above 38-40°C for extended periods, the stems and leaves turn yellow and wither, and plant growth and flowering will be adversely affected. After May, ventilation needs to be increased to lower the ambient temperature and keep it cool.

II. Propagation and Seedling Cultivation

This can be divided into seed propagation and cutting propagation.

1. Seed propagation: Seeds can be sown for propagation in April. The minimum temperature for seed germination is 8-12°C, and the optimal temperature is 20-25°C. Transplanting is done in May. However, lavender seed propagation has greater variation and seeds are relatively expensive, so cutting propagation is mostly used in production. Lavender from cutting propagation has stronger adaptability and can be done in both spring and autumn. It can even be planted in summer, though management is more labor-intensive.

2. Cutting propagation: Generally, healthy, pest-free terminal buds (about 5-10 cm) or relatively tender, non-lignified branches are selected for cuttings. When taking cuttings, remove the leaves from the bottom 2 nodes, then dip them in a 100-fold dilution of "Root Sun" rooting agent. After treatment, insert them into soil and roots will form in about 2-3 weeks. The cutting medium can be river sand mixed evenly with rice husk at a 2:1 ratio, placed into 5×10 plug trays for cutting. After cutting, place the seedlings in a ventilated, cool environment. Keep the soil moist for the first 3 days, then water depending on weather conditions, ensuring the branches do not wrinkle or dry out, to improve the survival rate. Cutting seedlings are relatively easy to manage, requiring no fertilization throughout the entire seedling period, and are widely used in production.

III. Transplanting Management

Lavender seedlings can be transplanted 1 week after roots emerge from the plug tray. When transplanting, keep as much soil around the roots as possible to ensure the survival rate. Before planting, water the soil thoroughly and completely. After planting the seedlings, spray water once more. When planting, the soil ball of the lavender seedling should be level with the soil surface, not planted too deep or too shallow. The plant spacing should be 20×25 cm. For the first 3 days after planting, water once every evening, then water depending on weather conditions. Fertilize after 5 days. Before fertilizing, moisten the soil first, apply a small amount of compound fertilizer 8 cm from the lavender, and water the next day depending on how dry the soil is. After 10 days, pinch the top once depending on the lavender's growth to encourage more branching. At around 20 days of growth, if there are few branches and the plant is not dense, apply fertilizer once more and pinch the top again. Otherwise, the lavender does not need a second fertilization or another pinching. However, excessive fertilizer and water can easily cause lavender lodging, overly dense branches and leaves, and stem rot. Lavender generally blooms about 30 days after pinching.

When lavender begins to form flower buds, spray a 0.2% potassium dihydrogen phosphate solution once a week until flowering. This can promote longer flower spikes, firm pedicels, vivid flower colors, resistance to lodging, and neat, beautiful blooming.

After lavender finishes one round of blooming, it must be pruned. Cut off the old branches and apply fertilizer. Let the plant grow new branches and bloom again.

IV. Pest and Disease Control

Lavender has relatively few pests and diseases. The main pest is the whitefly. Whiteflies mainly gather on the undersides of leaves, sucking plant sap and causing leaves to fade, curl, and turn yellow. They can be controlled by spraying thiamethoxam or acetamiprid. If there are many whiteflies, spray again after 5 days. The main diseases are stem rot and downy mildew, which can be controlled by spraying a 600-800 fold dilution of Ridomil MZ or a 0.2% solution of 65% zineb wettable powder.