A Detailed Guide to Eustoma Planting Methods and Key Technical Points

Eustoma (Eustoma grandiflorum (Raf.) Shinners), also known as lisianthus, is a perennial plant of the Gentianaceae family, with a plant height of 30-100 cm. The leaves are opposite, broadly elliptic to lanceolate, almost sessile, with the leaf base slightly clasping the stem; the leaf surface is blue-green. The stamens and pistils are prominent, the bracts are narrowly lanceolate, and the petals are arranged in an imbricate pattern. The flower colors are rich, including single colors and bicolors, and the petals are divided into single and double forms.

Cultivation Management   

1. Light Regulation 

Eustoma is fairly sensitive to light, and long-day conditions promote its stem and leaf growth and flower bud formation; generally, 16 hours of light per day gives the best results. There are generally two methods of supplemental lighting cultivation: one is intermittent lighting, that is, adding several hours of light at night; the other is extending lighting, that is, extending the light period in the evening. Generally, the first method gives better results. During winter and early spring, special attention should be paid to supplemental lighting, usually adding 2-4 hours at night. 

  2. Temperature Control 

The suitable growing temperature for Eustoma is 20-24°C during the day and 16-18°C at night. Its growth rate, such as the degree of internode elongation, the speed of flower bud differentiation, and the length of the harvest period, is very easily affected by temperature and changes accordingly. Therefore, from autumn and winter to early spring, heating is needed, and it is even better if heating can be provided at night or during cold spells. Generally speaking, early-maturing varieties have lower temperature requirements. If the temperature is too high, the growth period is shortened, the plant becomes shorter, and the possibility of rosetting increases. Especially at the seedling emergence stage, high temperatures can lead to a reduction in flower number, excessive elongation of upper internodes, weak peduncles, and poor quality; but if the temperature is too low, growth will be delayed or the plant may even fail to bloom.  

 3. Fertilization 

  Eustoma is a plant with relatively high fertilizer requirements, and if the base fertilizer is insufficient, topdressing is very important. 

  Eustoma not only requires sufficient macronutrients, but also requires that the soil contains a relatively large amount of calcium, while maintaining a suitably high soil pH value to facilitate the uptake of elements such as calcium and zinc. Usually, fertilize once every half month during the growing period, alternating 14-0-14 and 20-10-20 fertilizers, with a concentration of 100-200 ppm being suitable. When fertilizing, pay attention to the ratio of nitrate nitrogen to ammonium nitrogen. Usually ammonium nitrogen makes stems and leaves grow faster, leaves become larger and softer, and leaf color darker, but it easily causes excessive vegetative growth, especially when the temperature is too low, it should not be used. Potassium nitrate and calcium nitrate can be supplemented, but during the flower bud formation period, supplementation should mainly be with potassium nitrate. When the plant has grown to the 7th node, about 6 weeks after transplanting, phosphorus and potassium fertilizers must be specially supplemented. They can be sprayed onto the plants as an aqueous solution to make the stems and branches thick and strong so they do not droop softly. If nitrogen fertilizer continues to be supplemented, then in addition to thin stems, the internode length will also elongate, causing inconsistent lengths between upper and lower internodes. 

  The salt concentration of the medium for growing Eustoma must not be too high, and the EC value should be lower than 1 ms/cm. Therefore, before transplanting, first determine the salt concentration in the medium.   During high summer temperatures, the tips of new leaves of the plant will appear scorched, which is a calcium deficiency phenomenon. Strengthening ventilation and increasing transpiration is the best way to avoid calcium deficiency. Calcium ions are usually brought into the leaves by the vacuum suction generated during transpiration. Ventilation should be done well before calcium deficiency occurs to be effective. The benefit of ventilation also includes lowering the temperature, so that flower color is not prevented from showing due to high temperatures. 

  If in the middle and late stages of growth the stems are easily broken, or there is longitudinal splitting of the stems, it may be caused by boron deficiency. Spraying the plants with a diluted boric acid solution can improve this phenomenon. 

  4. Watering 

  Eustoma has strict water requirements. Too much water will cause poor root growth and also make it prone to disease infection; too little water will make stems and leaves thin and weak and cause early flowering. Within one month after transplanting, the medium must be kept moist, and drip irrigation can be used to control moisture. Especially after the flower buds have formed, a high-temperature and high-humidity growing environment should be avoided as much as possible.   

 5. pH Value 

  Because the pH value of the native habitat of Eustoma is 7.0-8.0, the pH value of the cultivation soil is best at 7.0, and is generally kept at 6.5-7.0. If the pH is too low, it will cause poor growth, scorched leaves, and even failure to grow flower buds. The pH value can be adjusted by applying quicklime.  

 6. Netting 

  To prevent lodging, install netting when the plant height is 15 cm. The net should be raised as the plants grow. The mesh size should be adjusted according to plant density, with 15×15 cm or 15×20 cm being more suitable. For plant heights below 80 cm, install one layer of netting; for heights above 80 cm, install two layers of netting.   

 7. Pests and Diseases 

  Diseases: Common diseases mainly include damping-off, gray mold, and sclerotinia rot. In addition to promptly pulling out diseased plants and removing diseased leaves and flowers, and applying agents such as kangluning, wanmeiling, and mancozeb for prevention and treatment, ventilation and air exchange should be strengthened at ordinary times to reduce air humidity.   Pests: These include aphids, leaf rollers, tobacco cutworms, and leafminers. Apply the corresponding pesticides according to the occurrence situation.