What Are Flowers of Sulphur?

Flowers of sulphur (sulphur) are a purified form of elemental sulphur called sublimed sulphur in scientific circles. Flowers of sulphur are produced by distillation. The resulting powder is chemically active and has several important uses, including preserving fruit, fertilising plants and controlling certain kinds of pests.

Chemical Composition

Flowers of sulphur is a fairly pure form of elemental sulphur, with only a few impurities. It includes some oxygen, and it slowly oxidises to form a small amount of sulphuric acid, or H2SO4. Flowers of sulphur should not be confused with flour of sulphur, the ground form of a less pure variety of sulphur called roll sulphur or cast rhombic sulphur. Sulphur is a non-metal and is the fifteenth most abundant element in the Earth's rocky crust and upper mantle.

Physical Characteristics

Flowers of sulphur is a pale yellow powder that may form larger clumps when exposed to air and moisture. It is not water-soluble but can be dissolved in non-polar organic solvents, such as carbon disulfide and benzene. The powder has a smaller particle size than the less pure flour of sulphur. Because of this small particle size, it may disperse in the air, forming a dusty miasma in sufficient concentrations.


Sulphur is flammable, with a flashpoint of 207 degrees Celsius and a spontaneous combustion temperature of 232 degrees C. It may ignite explosively if the dust becomes airborne. Airborne dust is also an inhalation hazard. It may cause skin or eye irritation. While flowers of sulphur are not poisonous, ingesting large amounts may cause sore throat, headache and nausea. Store flowers of sulphur in a tightly sealed container in a cool, dry location.


Burning flowers of sulphur in the presence of fruit preserves it for drying. This sulphur pretreatment prevents browning and reduces nutrient loss. Flowers of sulphur are also effective as an insecticidal dust, commonly used against the mites that cause scabies. The powder, once applied, slowly oxidises to form the active ingredient sulphur dioxide. Flowers of sulphur are also an elemental form of sulphur that is suitable as a plant fertiliser. Sulphur soil deficiency is fairly common in areas with high rainfall and low organic matter.

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About the Author

Based in central Missouri, Rachel Steffan has been writing since 2005. She has contributed to several online publications, specializing in sustainable agriculture, food, health and nutrition. Steffan holds a Bachelor of Science in agriculture from Truman State University.