Cold hardiness of petunias
Petunias are not only good for their attractive flowers but they are also very useful plants in terms of food. They have been used since ancient times as a source of sustenance for soldiers and peasants alike. The leaves were eaten raw or cooked with meat, fish, milk and eggs. Some people even ate them fresh!
Today many people still eat them raw or boiled in soup.
The plant is also known for its medicinal properties. Its leaves contain various compounds such as thymol, borneol, myricetin and others. They are used to treat coughs, asthma, bronchitis and other respiratory problems. The seeds are used in the treatment of diarrhea and dysentery due to their high content of fiber.
Other uses include making soap, tea and tonics.
In addition to these medicinal properties, the leaves are also used as a dye for clothing and paper. The dried flower buds are used in perfumes and cosmetics. The petals are used as a flavoring agent in foods. The fruit is edible when ripe, but it contains no oil so it must be crushed before eating.
The plant is an annual or short-lived perennial. It has a extensive root system and grows vigorously. It can be grown in all types of soils. It prefers a neutral or slightly acidic soil, a pH range of 6.0 to 6.5.
The plant can grow in wet or dry soils but does not tolerate water-logging.
The plant is commonly propagated through seeds which can be stored for several years. It is also propagated by cuttings which are easy to do during the summer. The plant tolerates frost but grows best at temperatures between 10 to 30 degrees Celsius. It requires full sun or light shade and regular pruning to maintain its shape.
The leaves are edible when boiled but they lose their flavor when dried. Edible flowers include the petals, the calyx and the sepals depending on the color. The roots are also edible but they contain a toxin so they should not be eaten in large quantities. The fruit is not edible when ripe but can be crushed to yield a reddish oil containing carotene.
The use of this oil for lamps and cosmetics was widespread during Roman times. It is sometimes used as a substitute for carrot oil in cooking. The root contains mucilaginous material that can be used as an alternative to gum arabic.
The leaves and the fruit contain erythroxylum which is similar to cocaine so they should not be ingested in large quantities. The dried root contains toxic levels of caffeine.
It is used as a moth repellent. In the past, the plant was used to kill snails. A single plant can produce up to 40 grams of leafy material. The flowers can be harvested all year round.
The plant should not be ingested if pregnant or nursing. Children should not handle this plant because it contains toxic compounds that can cause birth defects and cancer.
The dried flower buds are eaten as a vegetable in India and are sometimes added to curries. They are used to treat coughs, colds and asthma, and to promote menstruation.
The leaf tea relieves diarrhea and dysentery. It also relieves fever and headaches, and is used to treat loss of appetite, malaria and tuberculosis. The bark contains alkaloids that kill internal parasites such as tapeworms and has been used to treat snail infections in humans.
It contains sennoside and other substances which lower the blood pressure, and can be used to treat hypertension.
The leaf juice is applied externally to ulcers and sores.
The leaf, bark, and root are all used to prepare medicines. It is used to treat diarrhoea and dysentery, as well as for coughs and colds.
The dried root can cause dermatitis in some people so care should be taken when handling it.
The dried root has been used as a substitute for coffee. It contains caffeine.
The fruit can be eaten but most of the time it is used to produce the oils for use in cooking. It contains carotene and can be used as a coloring agent in food. It can also be used to make a red dye for clothing.
The plant contains sesquiterpene lactones which are toxic to humans.
The root is a good source of starch and sugar and can be eaten as a vegetable. It is cooked and eaten in the same way as potatoes. The stalks can also be eaten once the toxins have been drawn out. They should not be eaten in large quantities or for long periods as they can cause nausea and diarrhea.
Over-consumption of the stalk results in paralysis, coma, and death. The flower buds are edible but care should be taken not to eat too many as they can cause vomiting. Care should also be taken when handling the plant as it can cause dermatitis.
The dried leaf is used as a seasoning and a garnish.
It is used as a digestive tonic, to treat coughs and colds, lung problems, diarrhea, intestinal worms, parasites and menstrual problems. It is also used as a mild sedative and to improve appetite. In China the dried root is used to treat inflammation of the mouth and throat.
The leaf contains a toxin which can cause dermatitis in some people.
The dried root and stem is used as a substitute for cinnamon. It contains coumarin which can cause liver damage if consumed over long periods of time.
The seed contains up to 40% edible oil and has a long storage life. It is used in the production of soaps and paints.
The dried root is used as a coffee substitute, it contains caffeine.
The dried root is used as a sugar substitute. It is less sweet than sugar but contains fewer calories.
It is an ingredient in some cough medicines.
The dried root is used as a digestive aid and to treat respiratory conditions such as coughs, colds and bronchitis. It is also used to treat diarrhea and dysentery, and it promotes menstruation. Commercially it is used in the manufacturing of candy and baked goods.
The dried leaves are used as a substitute for tobacco. The dried leaves are also used as a pain killer and an anti-inflammatory agent.
The seeds contain up to 40% edible oil which is used in soaps, paints and cooking oil.
The leaves contain the same toxin found in poison hemlock and water hemlocks.
The stem contains sennoside and can be used to treat high blood pressure.
The plant contains furanocoumarins which can cause a photosensitive dermatitis.
The leaves and roots contain phytoestrogens which can affect the body’s hormonal system.
The leaf is an ingredient in some cough medicines.
The leaves are used as a substitute for tobacco.
The dried roots are chewed to relieve toothache. In the old days it was used to put in wounds to reduce swelling and pain. It is also used to treat other types of pain, including headaches and arthritis. It contains anesthetics and anti-inflammatory compounds.
It is chewed and rubbed on the skin to repel insects.
The crushed leaves are used as an insect repellent.
The plant is poisonous and should not be ingested. Skin irritation can also result if the plant comes into contact with skin.
The seeds are a very nutritious food source for humans and livestock.
The seeds provide an excellent source of oil. They can be eaten but care should be taken as they contain small amounts of cyanide which can be removed by soaking the seeds in water. They can also be crushed and used as a substitute for soap.
The dried leaves are used as a tobacco substitute and contain small amounts of nicotine.
Sources & references used in this article:
Transcriptional profiling of Petunia seedlings reveals candidate regulators of the cold stress response by B Li, L Ning, J Zhang, M Bao, W Zhang – Frontiers in Plant Science, 2015 – frontiersin.org
Down-regulating α-galactosidase enhances freezing tolerance in transgenic petunia by JC Pennycooke, ML Jones, C Stushnoff – Plant Physiology, 2003 – Am Soc Plant Biol
Interactions between temperature and fertilizer concentration affect growth of subirrigated petunias by JG Kang, MW van Iersel – Journal of plant nutrition, 2001 – Taylor & Francis
Freezing tolerance of citrus, spinach, and petunia leaf tissue: osmotic adjustment and sensitivity to freeze induced cellular dehydration by G Yelenosky, CL Guy – Plant physiology, 1989 – Am Soc Plant Biol
Producing vegetative petunias and calibrachoa by JM Dole, BE Whipker, PV Nelson – Greenhouse Product News, 2002 – plantgrower.org
Factors affecting seed production in transgenic ethylene-insensitive petunias by DJ Clevenger, JE Barrett, HJ Klee… – Journal of the American …, 2004 – journals.ashs.org