I callistemon are shrubs that love sunny locations, but develop without problems even in semi-shady areas. These plants can easily bear short periods of time with temperatures just below zero, but they fear intense frosts; in areas with harsh winters it is best to plant the plant in a place sheltered from the wind and cold, or to grow it in a container and shelter it from November to February.
These plants do not suffer from the heat and can bear even areas in full sun.
All callistemon prefer warm, sunny exposures. In these conditions they will grow quickly and give abundant and repeated blooms. Moreover, as we can also enjoy the heat in the winter months, we run less of a risk of seeing them deteriorate due to prolonged frost and water stagnation.
In the southern regions, however, it is possible to choose a location even in the middle of the shade.
- Callistemon are very common plants in gardens, even if their origin is quite exotic; in fact, these plants come from far away Australia, from areas where the climate is not so good.
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- To the genus kolkwitzia belong some species, native to China and Asia; the Kolkwitzia of China is a medium size shrub, with deciduous leaves, of roundish shape. It develops a short…
Watering and fertilization of Callistemon
These shrubs can also withstand very unfavourable growing conditions, even in dry soils; to obtain a good flowering and abundant development, however, it is best to water regularly, waiting for the soil to dry up well between one watering and the other.
During the winter period, water only as much as is necessary to keep the soil moist, waiting for it to dry between one watering and the next.
From March to October provide the plant with fertiliser every 15-20 days, dissolved in the water of the watering; alternatively, it is possible to provide only one fertilisation at the end of the winter, burying the mature organic fertiliser at the foot of the shrub.
During the summer, irrigation must be abundant, but without stagnation. We use rainwater or demineralised water as much as possible. The plant can withstand drought, but this can lead to a significant reduction in growth and flowering.
The plants in the ground need balanced fertilization at the end of the winter and in mid-summer. We prefer a product for acidophilic plants or at least a formulation in which they do not exceed phosphorus, potassium and calcium.
Land and Planting
It is good to plant in fresh soil, rich in organic matter, very well drained and slightly acid. Plants in containers 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 being fertile.
The best period for planting is undoubtedly the beginning of spring (until May) throughout the Centre-North. In the southern regions, especially in areas where it never freezes, it is also possible to carry out processing in autumn.
In the southern areas we prefer a well drained, but also rich soil, with a certain percentage of clay. In the northern regions it is good to prefer very draining and poor soils (mostly composed of acid soil, sand and gravel) so that the long wet winters do not cause rottenness to the root system.
The multiplication of Callistemon occurs by seed. The woody capsules containing the seeds are to be removed still closed, as they do not always open in the wild, whilst, keeping them for some days in a container in a warm place, they open easily. The callistemon propagate also by cutting.
IL CALENDARIO DEL CALLISTEMON
Dead wood removal
End of winter
Cleaning and trimming
End of spring
End of spring
Spring – autumn/summer depending on species
End of winter, mid-summer
Pests and diseases
In general, this type of plant is not significantly affected by pests or diseases, although occasionally aphids can spoil the inflorescences. In this case, it is a good idea to intervene punctually with the use of specific products that solve the problem before flowering or with natural methods that do not compromise it.
As we will specify when talking about the varieties, it is necessary, at the time of purchase, to evaluate the specific characteristics of the plant 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 provide a good insulating cover, with non-woven fabric or other suitable material.
Pruning is not strictly necessary. However, if we want to give a shape or reduce the size of the specimen, we should intervene in the autumn. Sick or compromised branches should be removed at the end of the winter, before the start of vegetative growth. At the end of spring it is advisable to eliminate wilted flowers to stimulate a second production and try to obtain a more branched and compact plant.
However, it is a plant that is very tolerant of cuts. If necessary, it is also possible to operate drastically, almost to the base.
IL CALLISTEMON IN BREVE
Family, genus, species
Mirtaceae, Callistemon, about 25 species
Type of plant
Trees and shrubs
Erect or Decumbent
Insulated specimen, borders, grove, hedge, vase
Height at maturity
Up to 5 m; on average 2 m
Speed of growth
Normal to fast
On average, frequent
Up to -15°C the most resistant; others up to -4°C for a short time
Sun, half shade
Draining but rich in the South, very draining in the North
For acidophilic, granular
Neutral to acid
The easiest way to get new specimens is to use cutting. It is done with semi-woody branches taken at the end of spring. They are inserted in a very drained compound (sand or perlite), with the help of a rooting powder. Rooting is slow, but the percentage of success is quite high. The plants can be planted as early as the following year and usually you are lucky enough to see them bloom immediately.
Callistemon: Species and Varieties
In the wild there are many species and also spontaneous hybrids. Recently, hybrids and varieties selected by man have been added to these. Thanks to this work we have the possibility to choose according to our tastes, as well as having individuals much more resistant to the cold.
Among the most rustic varieties we point out
– Callistemon hedges medium sized shrub (can reach 3 meters. It has beautiful dense foliage and lemon-yellow inflorescences. It can be grown throughout Italy, with protection in alpine areas, as it can bear even -15 ° C.
– Callistemon citrinus a tree that can reach a height of 3 m in a short time. It has lemon scented leaves and inflorescences up to 10 cm long, in red tones, erect or decumbent. It blooms mainly in spring, but it is not uncommon a second production in autumn, especially in mild climates. It can withstand temperatures as low as -12°C. Here are some cultivars
splendens up to 4 m, with new bronze jets. The red flowering is very long-lasting. It tolerates pruning well and is suitable for hedges.
White Anzac’. tall about 1 m and wide 3, has beautiful lanceolate leaves, first light green, then dark. It has white “brushes”, long up to 15 cm, produced very long. Tolerates calcareous soils well
Semperflorens small size and continuous flowering
Callistemon salignus Willow leaf: a tree that grows between 2 and 9 m in height. It has thick dark green leaves and new bronze jets. It blooms in spring and again in autumn in yellow, red or pink. Tolerates down to -10°C and soils averagely calcareous.
However, there are also more delicate species, suitable for the coasts and the Centre-South of our country, such as the
Callistemon viminalis small tree up to 2 m high (in cultivation) with drooping habit. Flower ears red, up to 15 cm long. Tolerates dryness and limescale well. Cold down to -4°C for short periods.
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