Eucalyptus RISDONII

Eucalyptus RISDONII - Risdon peppermint, Risdon eucalyptus.

Can be grown in bonsai style!

Eucalyptus is a vast genus of evergreen trees and shrubs in the family Myrtaceae, numbering several hundred species. Almost all of them originate from Australia and Tasmania, with only isolated species extending into New Guinea, Indonesia, and the Philippines.

The trunk is straight, up to 2 m (6.6 ft) across in large species. The bark in many eucalypts is smooth and light-colored, with the outer layer peeling and hanging in ribbons from the trunk and branches. The root system is powerful and capable of drawing water from great depths.

Eucalyptus leaves are unusual twice over: first, juvenile and adult foliage look completely different in most species; second, adult leaves are turned edgewise to the sun, so the tree casts almost no shade. Flowers sit in leaf axils on short pedicels, have no petals, and all the beauty is created by numerous stamens. The fruit is a woody capsule with small seeds.

Risdon peppermint is a small smooth-barked tree endemic to a small area in southeastern Tasmania. In nature, it occurs in a very restricted area and is therefore considered rare.

Its main feature is that the crown of an adult tree consists mainly of juvenile leaves: sessile, glaucous, ovate, arranged in opposite pairs. In most eucalypts, such foliage is retained only on young plants, but in this species it remains throughout its life. Flower buds are gathered in groups of 9-15, and the fruits are cup-shaped, conical, or hemispherical.

Eucalyptus seeds are very small, dark, and mature in woody capsules. Soaking such tiny seeds is impractical, so the substrate itself is disinfected: before sowing, it is drenched with a weak solution of potassium permanganate and dried. Scarification and stratification are not required.

Sowing is carried out in shallow bowls or trays with a mixture of equal parts turf soil and sand, to a depth of no more than 5 mm (0.2 in), or preferably without covering at all: in several eucalyptus species, germination is light-dependent. The sowing is moistened from a spray bottle with a growth stimulant solution: SUPERthrive, HB-101, Aminozol, Epin, or Zircon, covered with glass or placed in a mini-greenhouse, and germinated in light at a temperature of 18-20 °C (64-68 °F).

Under favorable conditions, the first seedlings appear as early as the seventh day, main germination is completed within 2-3 weeks, and individual seeds may delay longer. Special care must be taken with watering: eucalyptus seedlings easily perish from waterlogging and are frequently affected by damping-off (black leg), so containers are regularly ventilated and the substrate is kept slightly moist. Pricking out is carried out after the appearance of a pair of true leaves, one seedling per pot about 7 cm (2.8 in) in diameter, into a mix of equal parts turf, humus soil, and sand.

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The plant needs very bright light and is not afraid of direct sun. An eastern window is insufficient for eucalyptus: southern, southeastern, or southwestern exposures will do. In winter, supplemental lighting is needed, but the tree should receive about six hours of direct sunlight per day.

The main difficulty is temperature. Eucalyptus tolerates heat poorly at any age: even in summer it needs cool conditions around 18 °C (64 °F), which means frequent ventilation. In winter, the plant is moved to a colder location, 7-15 °C (45-59 °F).

Watering is regular during the growth period, after the top layer of substrate has dried out. In winter, with cool conditions, watering is noticeably reduced. The plant cannot tolerate stagnant water.

The substrate is selected to be loose and well-drained, made from turf and humus soil with the addition of coarse sand. Drainage is placed at the bottom of the pot.

Fertilizer is applied during the period of active growth, moderately: eucalypts do not like an excess of nutrients.

Eucalyptus grows very fast, so shoots are regularly shortened. Pruning simultaneously maintains a compact form and stimulates the emergence of new glaucous juvenile leaves.