Gas plant (Dictamnus albus), originally from Europe and Asia, is an easy-to-grow plant ideal for garden borders and cut flowers. It is so-named because it exudes a strong, citrus-scented vapor that is flammable. Some people experience skin irritation from the flowers and foliage.
I. Appearance and Characteristics
Dictamnus albus is a species of flowering plant in the family Rutaceae. It is also known as burning bush, dittany, gas plant or fraxinella. This herbaceous perennial has several geographical variants. It is native to warm, open woodland habitats in southern Europe, north Africa and much of Asia.
This plant grows about 40 cm (16 in) to 100 cm (39 in) high. Its flowers form a loose pyramidal spike and vary in colour from pale purple to white. The flowers are five-petalled with long projecting stamens. The leaves resemble those of an ash tree.
The leaves have a bitter and unpalatable taste. Despite the lemon-like smell, the plant is acrid when eaten. All parts of the plant may cause mild stomach upset if eaten, and contact with the foliage may cause phytophotodermatitis.
II. Types of Gas Plant
There are several gas plant varieties, the most commonly available include:
- ‘Caucasicus’: Growing up to four feet tall, this will work well for gardeners looking for an extra bit of height.
- ‘Purpureus’: The colors are what makes this variety stand out. The mauve blooms have distinct bright purple veins.
- ‘Rubra’: A rare variety, Rubra’s flowers come in pink shades.
III. How to Grow and Care
Gas plants are well suited to a sunny, sheltered garden that has fertile, moist, and well-drained soils. These plants have a sensitive root area that can sometimes mean they’re tricky to establish. Because of this, transplanting should be avoided where possible. However, once mature, they’re easy to maintain.
Sunlight
Gas plants do best when in a sunny position. They aren’t fans of intense heat, though, so if you live in a region that has especially hot afternoons, they might do better in a partial shade location.
Temperature and Humidity
Warm days and cool night temperatures are best for gas plants. It’s also best to avoid planting them in regions that suffer from strong winds unless you plant them in a fully sheltered position.
Because of their flammable qualities, some enthusiasts don’t recommend planting these flowers in arid and very hot regions where wildfires are common, especially if you want to position them close to your house.
Watering
Gas plants have a long taproot, and this means they’re relatively drought-tolerant. However, for best results, they prefer to be kept consistently moist, but not saturated, during hot and dry spells.
Soil
Well-drained, loose, reasonably fertile and slightly alkaline soils are preferred if you want your gas plants to thrive. However, they can still survive in poor soil conditions.
Fertilizing
Gas plants don’t need nutrient-rich soil to survive. For young plants or those in highly infertile soils, however, using organic fertilizer in the spring can be beneficial.
Pruning
Ideally, if you want to cut back your gas plant, you should leave this until the early spring. That way you’ll get to appreciate the decorative seed pods in the fall, and they could provide additional nourishment for birds in the winter.
Propagation
With their deep taproot, gas plants don’t take kindly to being disturbed once they’re established. For this reason, sowing from seed is preferable to division.
How to Grow From Seed
It can take a few years before gas plants are fully established and start to bloom, but they’re long-lived and will provide interest in your garden for many years.
The primary consideration is that the seeds don’t do well when stored for long periods, but they do need an extensive stratification period.
Some growers choose to sow them in the fall (if temperatures are mild enough). That way the seeds can stratify in the ground over the frosty winter period.
Alternatively, to guarantee optimal conditions, they can be bagged and kept in a moist, warm space for a fortnight to a month, before being removed and then put into the refrigerator for a month to six week period of cold stratification.
It can take six months to a year for gas plants to fully germinate and, ideally, they need to be kept warm and consistently moist throughout.
How to Get to Bloom
The gas plant blooms in late spring and summer with light purple-pink or white flowers. Seed pods that form after the blooming period offer ornamental interest.
It’s these seed pods that are the inspiration behind the plant’s common names—it’s also sometimes referred to as Burning Bush. The lemon-scented oil the plant pods contain is flammable. On particularly hot days, the oil can begin to steam, and the scent can fill the garden.
To encourage blooming, ensure your plant gets a minimum of six hours of sunlight. Deadheading is not required.
Pests and Diseases
Gas plant has no significant pest problems or plant disease issues.