Rhododendrum Lateritium

Class

Dicotyledons

Division

Angiospermae

Family

Ericaceae

Order

Ericales

Genus

Rhododendron

Species

lateritium

Description

A perennial species widely cultivated in the art of bonsai where it can become a unique specimen for its dense, small foliage from which emerges a spectacular spring bloom bearing flowers of different shades and hues depending on the variety. It requires acidic soil and particular attention to irrigation, which should be carried out with low-lime water.

Variety description

A member of the ericaceae family, the rhododendron genus includes hundreds of flowering species. The most familiar ones are grouped under the common names 'azalea' and 'rhododendron' and are normally used as house or garden plants, flowering in spring. Many species are native to China and Japan and have therefore been used in the art of bonsai over time.

Curiosities and special features

The azalea (tsutsuji) is widely cultivated, with its many varieties, as a bonsai tree in Japan where it is the symbol of spring.

The art of bonsai, i.e. the technique of growing miniature trees, has very ancient origins. It originated in China and spread to Japan, taking on profound meanings that reconcile philosophical and spiritual principles, in search of a symbiosis between man and nature. Today, also thanks to cultural exchanges and international events in the sector, bonsai cultivation has developed throughout the West.

Origin and distribution

Botanical species native to Japan.

Flower size

The flower is medium in size, lending elegance to the flowering.

Leaf

The small leaves have an oval lamina.

Flowering period

Flowering lasts from early spring to early summer for a duration of 10 to 15 days.

Leaf colour

Homogeneous tone.

Plant height

The height of the plant varies from 0.3 to 2.5 m, depending on the growing conditions and environment.

Lifespan

Perennial plant.

Where to plant

Species cultivated as potted bonsai , large pots, small pots, depending on the age of the specimen.

Stem

It has a woody stem with homogenous bark.

Flower

The flower has a simple, medium-sized form with a funnel-shaped corolla. The petals are bordered, with an eye, single-coloured, multicoloured, shaded and variegated. It flowers from early spring to early summer, with a flowering period of between 10 and 15 days. It is not particularly attractive to pollinating insects.

Growth

Medium-vigorous Growth plant.

Plant habit

The developed habitus is bushy, giving the plant a unique and highly ornamental plant architecture.

Branching

Medium branching.

PH

It requires an acidic soil pH between 4.0 and 4.5.

Sun exposure

Suitable for exposures in half-shade, full sun. In particular, it is a plant that prefers full sun in mid-season and half-shade in summer to protect it from too high temperatures that would cause excessive transpiration and water consumption; in winter it must be protected from frost and wind.

Ideal climate and temperature

The ideal temperature is between 12 and 20 °C. The vital temperature is between -5 and 35 °C.

Use

Appreciated, in different bonsai styles, in:

Ornamental

Hardiness

Of medium rusticity, it is very demanding in terms of irrigation.

Soil

Use a specific bonsai soil with an acid pH. If necessary, prepare a mixture of 60% acidic component (Kanuma), 20% porous part (sand, pumice...) and 20% peat-based soil rich in humus. In the late winter period, when the plant starts vegetating again, acidify the soil with iron sulphate.

Difficulty

Cultivation of Rhododendron lateritium as a bonsai is difficult on average, as it is a plant that requires great dedication for watering and great attention for exposure.

Growing tips

Some specific tips and useful cultivation indications:

Prefer shady locations in summer to avoid dry spells and high afternoon temperatures Always keep the substrate moist For a good, abundant and continuous flowering, fertilise well both in autumn and in spring at the vegetative restart and water regularly Prefers slightly calcareous water Requires abundant but no stagnant watering

Pruning

When the flowers fall, all new shoots must be cut back. In the vegetative period the secondary shoots should be pruned slightly, leaving 2 leaves, until mid-summer. From mid-August further pruning should be avoided to allow the buds to induce flowers.

Repotting

Normally every two years for young specimens and every four years for more mature specimens, when flowering is over. Also for repotting, use an acidic, bonsai-specific potting soil.

Watering

During the vegetative season, daily and abundant irrigation above the foliage with non-calcareous water, such as rainwater or demineralised water; it may sometimes be sufficient to mix aqueduct water with rainwater in a 50+50 ratio. In the flowering period, apply under-irrigation frequently. During the summer period it is advisable to also water the leaves to reduce the surface temperature while in the winter it is necessary to reduce watering, but keep the soil fairly moist.

Fertilising

It is advisable to apply specific organic bonsai fertilisers to the pot under the foliage, to be applied monthly throughout the growing season. In spring, until flowering, it is preferable to additionally fertilise with potassium-rich fertilisers.

Edibility for humans

Non-edible.

Tip

Always use acidic soils. Water with non-calcareous water, preferably rainwater or demineralised water. It may sometimes be sufficient to mix aqueduct water with rainwater in a 50+50 ratio In late winter, when the plant starts growing again, acidify the soil with iron sulphate Never allow the substrate to dry out too much, even in winter. If necessary, totally immerse the soil bed in water at room temperature (never <10°C, mai >25°C) for about ten minutes and then drain. Water again by sprinkling 3-4 hours after total draining and resume the usual frequency.