The Plectranthus, by all known as incense plant, is a perennial and evergreen herbaceous plant native to tropical regions. It belongs to the large Labiatae family, which includes all aromatic plants.
But the very intense scent that distinguishes the incense plant, and which gave it its common name, creates confusion. In fact, in reality, the incense used in liturgical rituals is obtained from the oily resin that is extracted from another plant, the Boswellia sacra.
Although it is not really incense, the scent emanating from the plant is an effective repellent for insects, especially mosquitoes. For this reason it can be very useful to grow even a single incense plant on a balcony or in the garden to keep these pesky animals away.
In addition, the incense plant has anti-inflammatory and antihemorrhagic properties, which help in the treatment of rheumatism, arthritis, gout and even ulcers. And for its antimicrobial and balsamic characteristics it is useful to fight respiratory diseases, such as asthma, catarrh and colds.
The incense plant is a very decorative plant that grows luxuriantly and with little care both in pots and in the ground.
This makes it a very popular ornamental plant and has determined its success to enrich gardens, terraces and balconies.
It can have both a creeping habit and be used as a ground cover or border, or have a climbing or hanging structure, for thick bushes or hanging baskets.
The incense plant is formed by several flexuous stems and by very perfumed green leaves with white streaks on the margins. The stems and leaves are covered with a slight down.
It blooms in summer with flowers gathered in apical ears, in the colours of white, pink, lilac or mauve.
The incense plant contains about 250 different varieties. Among the most common are:
- The Plectranthus Amboinicus, has an erect posture and can reach 70 cm in height. It is a variety suitable for pot cultivation and for borders. It is characterized by the scent of thyme of its leaves, which for this reason can also be used in cooking.
- The Plectranthus Australis, has a bushy habit and grows up to one metre. Suitable for cultivation both outside and inside the house, it has dark green leaves and white or mauve flowers.
- The Plectranthus Ciliatus, with variable bushy appearance, erect at the beginning, then climbing and decumbent when ripe. It grows up to 60 cm and is suitable both for the cultivation in pot and as soil cover. It is characterized by an original curled foliage, with purple veins and contrasting shades.
- The Plectranthus Coleoides, has a mostly decumbent appearance and for this reason is utilized as soil cover or in suspended baskets from which come down its bushy and drooping foliage. Just the Plectranthus Coleoides has that characteristic perfume which recalls incense and which has given the common name to all the plants belonging to this genus. It has a variegated light green and cream foliage and light purple flowers.
- The Plectranthus Dolichopodus, grows quickly and reaches a remarkable height, creating a lush bush very useful to provide shade especially in the garden. At the end of summer it blooms with characteristic purple flowers, but is more demanding in cultivation.
- The Plectranthus Oertendahlii, is the most widespread and known. It does not exceed the 20 cm of height and is perfect as soil cover, but also for the cultivation in pot. The leaves are round and velvety to the touch, of a nice dark green with silvery veins and purple tones on the back.
Cultivation Of The Incense Plant
Cultivating the incense plant is very simple. Let’s see what are the necessary cures.
The incense plant prefers shady places and sheltered from the wind.
Ideally, it should be placed in places where it can enjoy a lot of light and partial shade. In the house it is very good near a window, outside it resists to the half sun, provided that not in the hottest hours of the day. It suffers greatly from the cold and therefore it is appropriate to place it inside in the winter season.
Planting and soil
The right time to plant or transplant the incense plant is from April to May.
Repotting, on the other hand, can be carried out at any time of the year, choosing a container that is at least three times the volume of the roots.
The best soil is mixed, composed in equal parts of leaf earth and fertile garden earth, with addition of sand and peat, but especially well drained.
The incense plant wants an always fresh soil, which is never dry and dry to the touch.
For this reason, it should be irrigated more frequently during the summer months and more moderately in winter. The important thing is to avoid water stagnation and not to accumulate water in the saucer, because the roots could rot.
To maintain adequate humidity it may be useful in summer to vaporize water on the leaves, while, if in winter the plant is placed indoors near a radiator, it is advisable to place a bowl of water on the radiator.
For the outdoor specimens, it is possible to provide with a thick vegetal mulch.
To fortify the incense plant, a universal liquid product can be added to the watering water every 15 days from April to September, or granular slow release fertilizer can be added to the soil.
During the winter months, fertilisation may be limited to once every 2-3 months.
At the beginning of spring, you can top off the old branches of the plant, to maintain a lush and tidy appearance.
Instead, at the end of winter, if you want to stimulate the regeneration of the incense plant, you can intervene more drastically, leaving about 1/3 of the initial length of the stems.
Propagation by cutting of the incense plant
The propagation of the incense plant takes place mainly by cutting and is a very easy operation.
Cuttings can be made at any time of the year, but better results are obtained in the period between August and September.
- With a well-sharpened knife, it cuts an apical segment of the stem, about 10 cm long.
- It removes all the leaves, except for a few on the top.
- Place the resulting cuttings in a mixture of soil and sand, which you will always keep moist.
- Place it in a shady place and at a temperature of about 20°.
- Rooting will take place after about six weeks. Now, you can place the resulting plant in a pot with the final compost.
Diseases And Pests Of The Incense Plant
The incense plant is rarely attacked by parasites. However, it may happen, if it is placed next to infested plants, that you see on aphid stems or red spiders. To eradicate them, simply spray a specific insecticide on the plant.
Problems could be caused by poor plant care. If the soil is not well drained or the water stagnates in the saucer, the leaves could turn yellow and wither easily and the lower part of the stems and roots could rot.
In this case, it is sufficient to reduce the watering, to change the mould and to avoid that it becomes too much humid, or, maybe, to move the plant in a sunny place. But the yellowing of the leaves can come also from a too direct exposition to the rays of the sun.
In presence of an excessively humid climate, the incense plant can be attacked by the powdery mildew, or bad white, which is to be treated with specific products and by intervening on the excessive humidity which has caused the onset of the disease.
Although it comes from southern Africa, the incense plant is also known as Swedish ivy.