Sweet flag is a great wetland or boggy area plant. It is hardy to zone 3 and not really fussy about soil type. It does best with good rich soil but it will grow in other conditions. It cannot tolerate getting dry. Ideal for boggy areas, sides of streams or in ponds. Will spread rapidly once established and needs little if any care. The whole plant has a lovely aroma and the roots are edible. Not suitable for rain gardens as they tend to dry out at times. We don't think the deer eat it but cant be certain.
Description of Sweet Flag (Acorus calamus).
Sweet flag is a hardy wetland perennial plant with sword shaped leaves that strongly resemble those of Iris plants but are greener. Their resemblance is what gives this plant its common name 'sweet flag' as the leaves resemble the yellow flag iris. However, the plant is not an iris, a rush or a sedge despite its many common names.
Sweet flag has a spreading rootstock from which every spring a tuft of basal leaves emerge. They are sword shaped, flattened with one wavy edge and a prominent midrib with other parallel veins. These leaves are about ¾" (2 cm) wide and up to 4 feet (122 cm) tall, and fairly bright green. In late spring some leaves develop a 'flower' which is a cylindrical spadix, usually 2-4" (5-10 cm) long and semi erect and just below the leaf tips. This spadix is covered with tiny greenish yellow flowers in a diamond-shaped pattern. Flowers last for about a month and are very sweet scented. Sweet flag is pollinated by insects, which ones is not precisely known. However although these occur in the United States and its original home in India and Asia they do not appear to be present in Europe. Hence the plant does not produce fruit in that continent. Where it is pollinated the fruit is a tiny greenish berry which is sparingly produced. The whole plant is aromatic and emits a pleasant aroma when bruised. It is hardy to zone 3.
Location and Care of Sweet Flag (Acorus calamus).
This is a wetland plant and needs water. It also needs full sun but will tolerate a little shade especially in higher numbered zones (7 and higher) . It prefers rich soil for the best growth but will grow in poorer soil but not as well. It will grow in standing water, boggy soils or soils that are consistently moist. It can be grown in any garden provided the water is provided for it, but it is ideal for stream sides, ponds and wet areas. It is not recommended for rain gardens as these often dry out during the year.
For best results ensure that the soil has plenty of organic material dug into it. Plant out slightly below the soil surface in moist soils or at the water's edge. The leaf tips will scorch if the soils dry out. Plant about 10 inches (25 cm) apart. When established the plants will grow rapidly and spread out.
Plant spread will only be limited by the size of the wetland. If containment is required plant in containers to prevent sweet flag from taking over the area. Sweet flag is very hardy, easily to zone 3. It dies down and goes dormant every winter. Provided that the plants do not dry out sweet flag needs almost no additional care or maintenance. Just plant and enjoy.
Growing Sweet Flag (Acorus calamus) from seed.
Best grown in small pots with a few seeds per pot, depending on the size. Stand pots in about 1 inch (3cm) of water to ensure they are constantly moist. Pot up seedlings as soon as they are large enough to handle. Keep wet by standing pots in shallow water and harden off outside. Once the plants are large enough plant out in final location about 10 inches (25 cm) apart. As long as they are kept moist they need very little additional care.
Pests and Problems with Sweet Flag (Acorus calamus).
There are no serious insect or disease problems. Scorch will occur if soils are not kept consistently moist to wet. The main problem is aquatic animals. Muskrats love to eat the tubers. If you are planting in a wetland situation these can be a major problem. At present we are unsure if deer eat them, they have not eaten ours yet and they are outside our main deer fence. However they are not on the 'deer route' and may just not have been discovered yet.
Harvesting Sweet Flag (Acorus calamus).
Roots. It is the root that is used for medicinal purpose. Rhizomes are usually harvested during their second or third year when they are large enough and still firm. Older rhizomes tend to become hollow. The best time is late autumn or early spring. Roots must either be dug from the soil or raked up from ponds and streams. Fresh rootstock is brownish red or white green with a spongy texture. They have a sweet aroma and bitterish pungent taste.
Leaves. Leaves are also very aromatic and have long been used as a 'strewing' herb. Placed on the floor to be walked upon these were often used in Religious rituals and special occasions. Leaves can be harvested at any time during the growing season provided they are large enough. Do not take all the leaves from one plant as it will deplete the rhizome and it may not recover.
Edible uses of Sweet Flag (Acorus calamus).
The rhizome can be pealed and washed to remove the bitterness then eaten like a fruit. It can also be roasted and used as a vegetable, or it can be candied and used as dessert. The dried and powdered rhizome has a spicy flavour and is used as a substitute for ginger, cinnamon and nutmeg.
The young leaves can be cooked and used as a vegetable or to flavor desserts in the same way vanilla pods are used. The inner portion of the young stems can be used in salads. The flowers are sweet and can be eaten raw.
Medicinal Uses of Sweet Flag (Acorus calamus).
Sweet flag has a very long history of use in herbal medicine. In Ayurveda it is highly valued as a rejuvenator for the brain and nervous system and as a remedy for digestive disorders. It is used internally in the treatment of digestive complaints, bronchitis, sinusitis . It has been reported to be very useful in stimulating and normalizing the appetite. In small doses it reduces stomach acidity whilst larger doses increase stomach secretions and it is, therefore, often used in the treatment of anorexia nervosa. Native Americans have long used this herb. They would chew roots to increase energy and stamina. The roots will act as both a stimulant and as a sedative allowing the body's energy to be placed in balance. For this reason it is an excellent choice for treatment of panic and anxiety attacks as well as for daily stress and anxieties. However long term use can cause fatigue and exhaustion. Chewing the root is said to kill the taste for tobacco and to clear the voice. However large doses can cause nausea and vomiting. Bath oils containing calamus have caused redness of the skin (erythema) and dermatitis, particularly in hypersensitive individuals.
Other uses of Sweet Flag (Acorus calamus).
Both the root and the leaves are sometime added to herbal smoking blends or mixed with tobacco.
The leaves are used to make baskets or woven into mats. An essential oil is made from the plant and used in perfumery and as a food flavouring. It can also be used as an insect repellant and insecticide and added to rice it reduces loss by insect damage. The dried leaves can also be used to line cupboards and storage areas to repel insects and keep the area smelling sweet. It is also burnt as incense.
Known Hazards of Sweet Flag (Acorus calamus).
The fresh root of some populations can be poisonous. There are two different forms of this plant. The triploid form of the species is found in Asia This contains the compound asarone. This has tranquillizing and antibiotic activity, but is also potentially toxic and carcinogenic. However the diploid form of sweet flag found in North America and Siberia is free of these compounds. The roots have been used in India for thousands of years with no reports of cancer. In more recent times the essential oil has been extracted from the roots and used in medicine. It appears that this concentrates the unwanted compounds so the essential oil and roots should be avoided for medicinal use. It is also recommended that only roots from known populations in North America or Siberia be used to avoid any possible problems. Use sparingly so overdoses are not an issue.
Synonyms---Calamus. Sweet Flag. Sweet Root. Sweet Rush. Sweet Cane. Gladdon. Sweet Myrtle. Myrtle Grass. Myrtle Sedge. Cinnamon Sedge. Calamus aromaticus