Dillenia INDICA

Dillenia INDICA - Indian dillenia, Dillenia indica, Elephant apple, Dillenia SPECIOSA, Elephant Apple, Chalta.

Dillenia is a genus of tropical trees and large shrubs in the Dilleniaceae family, comprising about one hundred species distributed from islands of the western Indian Ocean and South Asia to Australasia and the southwestern Pacific Ocean. They grow predominantly in moist tropical forests, along riverbanks, and in well-watered areas.

Representatives of the genus typically form a straight or short trunk, a spreading crown, and large alternate leaves with pronounced lateral veins, a serrate margin, and a dense, corrugated blade.

Flowers in dillenias are large, solitary or gathered in groups of several, more often white or yellow, with numerous stamens. After flowering, rounded or spherical fruits develop. In a number of species, the fruit is partially surrounded by enlarged fleshy sepals, while the seeds are enclosed within a juicy fruit mass.

Elephant apple is an evergreen tree or large shrub distributed from India, Nepal, Bhutan, and Sri Lanka to China, Myanmar, Thailand, Indochina, Malaysia, and Indonesia. In nature, the plant occurs in moist forests, along riverbanks, and in places with constantly available moisture.

The leaves are large, leathery, serrate, with deeply impressed parallel veins and a noticeably corrugated surface. Flowers are large, white or creamy-white, fragrant, with numerous yellow stamens. The fruits are rounded, greenish-yellow, dense, with sour fibrous pulp and small brown seeds inside the fruit segments.

In natural conditions, Dillenia INDICA can grow into a tree up to 15-30 m (49-98 ft) tall, with a straight trunk, large branches, and a broad crown. In cultivation, the size is usually much more modest and depends on the age of the plant, root system volume, and growing conditions.

The seeds are small, brown, and located within a juicy fruit mass. Before sowing, remnants of pulp are removed, as soiled organic matter in a warm humid environment quickly turns sour and increases the risk of mold. Scarification is usually not required.

Before sowing, the seeds are kept for 1-2 hours in a 1% potassium permanganate solution, then soaked for 12-24 hours in warm water with the addition of a growth stimulant: SUPERthrive, HB-101, Aminozol, Epin, or Zircon. Sowing is carried out on the surface or with light covering using a sterile loose substrate with the addition of sand or perlite. The sowing is moistened from a spray bottle and placed in a mini-greenhouse. Germination is carried out at a temperature of about 25-28 °C (77-82 °F), bright diffused lighting, and regular ventilation. The substrate is kept slightly moist, but not wet.

Under favorable sowing conditions, the first sprouts may appear in about 4-6 weeks; the main germination often extends to 6-8 weeks, while individual seeds can take longer. After sprouts appear, ventilation is gradually increased. Pricking out is performed after the formation of several true leaves and noticeable strengthening of the seedlings; young plants are transplanted into small pots with loose drained substrate and gradually accustomed to brighter light.

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For dillenia, a very bright location with direct morning or evening sun and protection from harsh overheating indoors is chosen. During the warm season, the plant can be kept outdoors after gradual acclimation, in a place sheltered from cold wind and drying out.

Warm greenhouse culture is optimal. During active growth, a comfortable temperature is about 22-30 °C (72-86 °F); with good lighting and high air humidity, the plant tolerates hotter conditions. Wintering takes place in a bright warm place, without root freezing or cold drafts.

Watering is carried out regularly, after light drying of the upper part of the substrate. During the active season, the root ball is kept evenly moist, but standing water is not allowed. In winter, watering is reduced according to temperature and lighting, while complete drying of the root ball is undesirable.

For planting, a nutritious, loose, and well-drained substrate of slightly acidic or near-neutral reaction is used. Coarse sand, perlite, zeolite, or another loosening fraction is added to the substrate. Drainage is placed at the bottom of the pot, and the pot itself is selected to be stable, with drainage holes for water runoff.

Fertilization is carried out moderately during the period of active growth using a fertilizer for ornamental foliage or woody container plants. Excess nutrition under deficient light is not applied, as it causes shoots to stretch and weakens young plants.

Pruning is carried out at the beginning of active growth or after the completion of the main growth flush. Shoots are shortened gradually to maintain a compact crown. Repotting is carried out as the pot is filled, maintaining a loose substrate and mandatory moisture control after repotting.