Lavandula or lavender consists of 47 flowering species of plants, from the genus from the Lamiaceae family. Its native range extends from the Canary Islands, Cape Verde, North Africa, Europe, southwest Asia, and India.
Many varieties of this genus are extensively cultivated as ornamentals, like herbs, and also grown commercially to extract essential oils for use in the cosmetic industry. The plant has been used in perfumery and cosmetics for thousands of years.
Today, there are several different hybrids being cultivated for essential oil production. The variety most commonly cultivated is English lavender (L. angustifolia). Other ornamental species that are commonly grown are L. multifida, L. stoechas and L. dentata.
Leaf shape is varied across the genus, ranging from simple to pinnate and sometimes multiple pinnate. The leaves in most species have fine hair that usually contains essential oils.
Flowers grow on spikes above the foliage, with some species having branched spikes. The color of the flowers range from blue, violet, lilac, and sometimes black-purple or yellowish.
Since these plants are cultivated in gardens all around the world, they sometimes escape the confines of the gardens and are found growing wild. Such natural growth is ordinarily harmless, but this species has become invasive in some countries.
English lavender (L. angustifolia) produces a sweet-smelling oil and is used in salves, balms, cosmetics, perfumes, and topical applications. Dutch lavender (L. × intermedia) produces a similar essential oil but has higher levels of chemical compounds including camphor, which adds a sharp overtone to its fragrance.
The Lavandula × intermedia (lavandin) are a group of hybrids from the L. latifolia and L. angustifolia varieties. They are widely cultivated as their flowers are bigger than English lavender and are easy to harvest, although the oil is deemed to be of lower quality and not as sweet-smelling as English lavender oil.
The fragrant flowers and buds have many uses – in potpourris, in sachets to freshen clothes and deter moths, as wedding confetti, and in scented waters.
Lavenders flourish in full sunlight, which guarantees plenty of flowers and big bushes. They can’t tolerate much shade, so shouldn’t be planted under trees or large plants.
This is a hardy, drought-tolerant plant once it is mature, but should be watered once a week during the first 4 weeks of growth and once every 14 days after that. This plant can handle protracted periods of drought — too much watering will lead to disease. Water it once a month during winter.
Humid environments with slow evaporation are not good for this plant as damp conditions can attract pathogens. Adequate air circulation is necessary if indoor humidity is too high. Good plant spacing is necessary when growing it outdoors as well.
This plant can tolerate temperatures of 68-86°F as temperatures over 65°F promotes good growth, particularly after harvest. However, it can also tolerate lower temperatures of -20-10oF but won’t survive if it gets below that.
Sandy soils encourage better production of oils, so don’t add too much organic matter or fertilizer. Well-drained soil is preferred – if you’re using regular soil, amend it with sand and gravel. Alkaline or chalky soil enhances the plant’s fragrance, while soils with a pH level below 6.5 will reduce the lifespan of the plant. It thrives best in pH levels of 6-8.
This plant can be grown indoors in pots, although it needs a lot of light to thrive. While it does have a large root system, it can grow in tight spaces. A pot that is 18 inches wide and a similar depth can house the root ball with a few inches to spare is good; any larger pot might increase the water saturation of the soil. It should also have good drainage capability to remove water. A clay or terracotta container will also help evaporate water from the soil.
Use a loose soil amended with plenty of perlites or something similar, as a container-grown plant requires more water than plants growing outdoors in a garden. Always water the soil to prevent the foliage from getting wet.
It can be propagated from seed – the germination process takes 14–28 days and the plant becomes mature in 100–110 days. However, this plant is best propagated by softwood cuttings from the shoots or hardwood cuttings from woody stems. Softwood cuttings can be had in spring while hardwood cuttings in autumn.
Cut a three-inch portion of a softwood shoot from a healthy stem. Hardwood cuttings must be taken just under a leaf node. Leave two or more leaves at the top of the cutting, remove the remainder and shave off the outer skin at the bottom on one side.
Fill a pot with damp seed-starting mix. Dust the scraped side of the cutting with rooting powder and plant it into the mix. Keep the pot covered with plastic in a warm place with plenty of indirect light. Softwood cuttings usually take two or four weeks to root while hardwood cuttings will take longer. When new shoots emerge, remove the plastic and keep it in a sunlit location.
Feed the new plant with 1/4 strength liquid plant fertilizer once a week for 2 or 3 weeks. After this period, the plant can either be moved outdoors or in a larger container with suitable soil.
Add some compost to the soil when you transplant or repot this plant. After that, it doesn’t need feeding as it can affect the quality of the aroma and essential oil extracted from the plant.
While this plant is regularly pruned for harvesting the flowers, some pruning in spring is suggested to keep the plant shaped and also to boost new growth for best drying practices, the flowers must be harvested when the buds first start opening. Tie them in bunches and dangle them up in a setting with suitable air circulation to dry. Taller species can be pruned down to around 1/3 of their size, while shorter varieties can be cut down a few inches.
If your plant lives in a place where foliage dies in winter, don’t remove dead foliage until new green growth appears. If the plant is disturbed too early, new growth might not develop.
Rich soil will affect reliable flower production since it will promote plenty of foliage growth and hinder flower bud production. Amend the soil with sand or gravel to add aeration and reduce nutrients.
Remember, only young plants need some light feeding for a few weeks and shouldn’t be fed again after that ensure the plant gets at least six to eight hours of sun every day for productive blooming. If you consider growing it under artificial grow lights.
The biggest problem that causes the plant to die is root rot and fungal infection from over-watering and water-logged soil. High humidity can also attract fungal growth, causing wilted black leaves and roots.
Remove diseased areas and cease watering until the plant dries out. This plant loves loose, sandy, or gritty soil that drains fast including a proper watering schedule. Frequently though, the plant cannot be saved once the rot has started and the only solution is to take cuttings of healthy stems and propagate them.
Yellow leaves commonly happen with these plants and can be due to different reasons. More or insufficient nitrogen can affect plants grown in containers while yellow leaves on plants growing in the ground usually indicate a problem with high humidity and poor drainage. Yellow leaves with gray or black color indicate a fungal problem. Identify the problem and treat the plant accordingly.