Many gardeners are familiar with the common ageratum, a tender annual. This low growing plant, also called floss flower, has small, puffy flowers and is commonly sold in garden centers. Purple flowers are most often seen, but ageratum also comes in pink and white. The medium green leaves are often oval or heart shaped.
Ageratum is native to South and Central America. It can grow in both full sun and part shade. Ageratum begins flowering in early summer and continues until a frost kills the plant. While ageratum may be hard to grow from seed it actually is very easy for beginners to maintain once it is larger.
Uses for Ageratum
In the United States floss flower is typically used as a bedding plant. It is good for edgings, borders, rock gardens and the fronts of flowerbeds. Ageratum is originally from Mexico. Some countries consider the plant to be a weed. But, in the 19th century gardeners in America and Europe began to cultivate it as an ornamental bedding plant. Bees, butterflies and birds love the floss flower. The plant can be poisonous if eaten.
Types of Ageratum
Different varieties of ageratum lend themselves to many purposes in the home garden. Some types of floss flower grow in mounds while taller types are more open.
These taller varieties make excellent cut flowers. For example, Blue Horizon is a tall ageratum variety that grows a couple of feet in height. On the smaller end, Blue Danube is a popular purple type that grows about 6 inches tall.
While blue flowers are most commonly available on ageratum plants found in garden centers, other types can be grown from seed. White Bouquet is an example. It has small white flowers. Hawaii Shell Pink is a recently developed variety that has delicate pink flowers.
How to Grow Ageratum from Seed
Floss flower can be a challenge to grow from seed, but some home gardeners like to be able to grow less common varieties. In order for ageratum to bloom in early summer, sow the seeds indoors six to eight weeks before the local last frost date. Prepare a pot or other container by filling it with soilless seed starting mix. Make sure the pot has holes in the bottom for drainage. Floss flower needs light to germinate so gently scatter the tiny seeds over the surface of the soil.
Keep the pots in a warm place, as ageratum will not germinate well in cold soil. The seedlings should emerge in about a week. Once the seedlings have three sets of “true” leaves (not counting the first pair that emerges from the newly sprouted seed) transplant the seedlings to small individual pots.
Planting and Caring for Ageratum
When all danger of frost has passed and the ageratum seedlings are about three inches tall, plant them outdoors. If buying transplants from a garden center, make sure they are healthy and strong and do not show signs of insects or disease. To plant ageratum outdoors select a spot with either full sun or part shade. Consider the local climate when selecting shade or sun. Ageratum plants will do better in partial shade during the hot days of midsummer, but it can still do fine in hot, dry weather.
While floss flower can also tolerate poor soil it does best in average soil. Space the ageratum transplants about six to eight inches apart as they usually grow about six to eight inches tall. They should bloom throughout the summer if they get enough water and sunlight. Deadhead the plants regularly to encourage new flowers. This entails simply removing the spent flowers, which will be brown and unsightly anyway. Aphids occasionally bother ageratum but otherwise pests are not attracted to them.
Resources
How to Grow and Care for Ageratum Flowers
Catherine Mezensky - Catherine A. Mezensky is a writer and artist living in Baltimore Maryland. Her topics include gardening, film, culture and local history. ...
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