Garden

Bottlebrush


GeneralitŠ°


The term Callistemon indicates a genus that has about thirty species of medium-sized evergreen shrubs, originating in Australia; it has a fairly slow growth and generally maintains a size close to 150-200 cm in height, there are also prostrate varieties, such as C. viminalis. The stems are erect, very branched, rigid, of a brown color; the small leaves are lanceolate, rigid and leathery, dark green in color, usually the new spring leaves are bronze or reddish.
Starting from late spring, until September, at the apex of the branches, long panicles blossom, made of small flowers with showy colored stamens; the inflorescence has the appearance of a down or a large brush, usually red, but there are species and cultivars with white, green, yellow or purple flowers. This very decorative plant is generally used as a single specimen, also as a sapling. Pruning is practiced after flowering.

Exposure



THE callistemon they are shrubs that love sunny positions, but develop without problems even in partially shady areas. These plants can easily withstand short periods with temperatures just below zero, but they fear intense frosts; in areas with harsh winters it is advisable to place the plant in a place sheltered from the wind and cold, or cultivate it in a container and repair it from November until February.
These plants do not suffer from the heat and can also withstand areas in full sun.
All the callistemon they prefer warm and very sunny exposures. In these conditions they will grow quickly and give abundant and repeated blooms. Moreover, being able to enjoy the heat even in the winter months, we will run the risk of seeing them deteriorate due to prolonged frosts and water stagnation.
In southern regions it is however possible to choose a location even in partial shade.

Callistemon watering and fertilizing



These shrubs also endure very unfavorable development conditions, even in dry soils; to obtain a good flowering and an abundant development it is however good to water regularly, waiting for the soil to dry well between one watering and another.
During the winter, they need to be watered just enough to keep the soil moist, waiting for it to dry between one watering and another.
From March to October, give the plant a fertilizer every 15-20 days, dissolved in the water used for watering; as an alternative it is possible to supply only one fertilizer at the end of winter, burying at the foot of the bush a mature organic fertilizer.
During the summer the irrigations must be abundant, but without creating stagnations. We use as much rain or demineralised water as possible. The plant is able to withstand drought, but this can lead to an important reduction in growth and flowering.
Plants in full ground need balanced fertilizations at the end of winter and in mid-summer. We prefer a product for acidophilic plants or in any case a formulation in which they do not exceed phosphorus, potassium and calcium.

Land and planting



It is advisable to place it in a fresh soil, rich in organic matter, very well drained and slightly acid. Container plants should be repotted every two years, at the beginning of spring or when the plant has grown enough to need a larger pot. They are rustic plants and for this reason they can grow well even in different soils, the important thing is that they are fertile.
The best time for planting is undoubtedly the beginning of spring (until May) throughout the Center-North. In the southern regions, especially in areas where it never freezes, it is also possible to carry out processing in the autumn.
In southern areas we prefer a well-drained but also rich soil with a certain percentage of clay. In northern regions it is better to prefer very draining and poor soils (mostly composed of acid soil, sand and gravel) so that the long wet winters do not cause rot to the root apparatus.

Multiplication


The multiplication of Callistemons occurs by seed. The woody capsules containing the seeds are still removed because they do not always open in nature, while, keeping them for a few days in a container in a warm place, they open easily. The callistemons also propagate by cuttings.




























Pests and diseases



In general, this type of plant is not significantly affected by parasites or diseases, although occasionally aphids can ruin the inflorescences. In this case, it is good to intervene in a timely manner with the use of specific products that solve the problem before flowering or with natural methods that do not compromise it.

Climate


As we will specify by talking about the varieties, at the time of purchase, the specific characteristics of the plant must be properly evaluated in relation to our climate. In the northern regions we will be able to choose only the most rustic varieties and it is advisable, at least for the first few years, to prepare a good insulating covering, with non-woven fabric or other suitable material.

Callistemon pruning


Pruning is not strictly necessary. However, if we want to give a shape or reduce the size of the specimen it is good to intervene in autumn. The diseased or compromised branches should instead be eliminated at the end of winter, before the vegetative restart. At the end of spring it is advisable to eliminate the withered flowers to stimulate a second production and try to obtain a more branched and compact plant.
In any case, it is a plant that is very tolerant of cuts. In case of need it is also possible to operate in a drastic way, almost up to the base.

THE CALENDAR OF THE CALLISTEMON
Pruning Autumn
Elimination of dead wood End of winter
Cleaning and topping End of spring
Talea End of spring
Flowering Spring - autumn / summer depending on the species
Composting Late winter, mid-summer





































































THE CALLISTEMON IN BRIEF
Family, genus, species Mirtaceae, Callistemon, about 25 species
Type of plant Trees and shrubs
Foliage persistent
Habit Erected or decombent
Use Isolated specimen, borders, shrubbery, hedge, vase
Height at maturity Up to 5 m; on average 2 m
Growth rate From normal to fast
Maintenance Moderately demanding
irrigations Moderately frequent
Minimum temperature Up to - 15 ° C the most resistant; others up to -4 ° C for a short time
Exposure Sun, half-shade
Ground Draining but rich in the South, very draining to the North
Fertilizer For acidophilic, granular
soil pH From neutral to acid
Soil moisture Well drained
Propagation Cutting, sowing

Propagation


The simplest way to obtain new specimens is to use the cuttings. It is practiced with semi-woody branches taken at the end of spring. They are inserted in a very drained compost (sand or perlite), using a rooting powder. The rooting is slow, but the success rate is quite high. The plants can be planted already from the following year and usually you are lucky enough to see them bloom immediately.

Callistemon: Species and Varieties


In nature there are many species and even spontaneous hybrids. To these have recently been added hybrids and varieties selected by man. Thanks to this work we have the possibility to choose according to our tastes as well as to have individuals much more resistant to cold.
Among the most rustic varieties we point out
- Callistemon sieberi medium-sized shrub (can reach 3 meters. It has a nice dense foliage and lemon-yellow inflorescences. It can be cultivated throughout Italy, with protection in the alpine areas, since it bears even -15 ° C
- Callistemon citrinus tree that can quickly reach 3 m in height. It has lemon-scented leaves and inflorescences up to 10 cm long, in shades of red, erect or decombent. It flowers mainly in spring, but a second production in autumn is not rare, especially in mild climates. Withstands up to -12 ° C. Here are some cultivars
'Splendens' up to 4 m, with new bronze castings. The red bloom is very long lasting. It tolerates pruning well and is suitable for the formation of hedges
'White Anzac' about 1 m tall and 3 m wide, it has beautiful lance-shaped leaves, first light green, then dark. It has white "toothbrushes" up to 15 cm long, produced very long. Tolerates limestone soils well
semperflorens small size and continuous flowering
Callistemon salignus, a willow leaf: tree that in culture stands at 2 to 9 m. It has thick dark green leaves and new bronze castings. It blooms in spring and again in autumn in yellow, red or pink. It tolerates up to -10 ° C and medium calcareous soils.
However, there are also more delicate species, suitable for the coasts and the Center-South of our country, such as the
Callistemon viminalis small tree up to 2 m in height (in cultivation) with hanging posture. Red flower spikes, up to 15 cm long. It tolerates dryness and limestone well. Cold up to -4 ° C for short periods.
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