Department of Horticulture New York State Horticulture Study Guide for Youth 4-H Logo


Flowers &
Indoor Plants

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Cornell University

Ageratum; Flossflower
Ageratum houstonianum

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What about it?

There are about 30 species of this plant that are known. It may be herbaceous or woody, but our common garden variety is a herbaceous annual. It is generally a compact-growing mound. The leaves are usually heart-shaped at the base. Flowers may be blue, pink or white; heads are about 1/4" across.

What is it used for?

Ageratum is often grown as an edging or border plant, since it ranges from about 4-24" in height. Because it is blue, a color not common among annuals, it is a familiar bedding plant, and is attractive in window boxes. like many annuals, its blooms last for much of the growing season.

Where does it gmw? How do we grow it?

Ageratum prefers moist, fertile, well-drained soil. It will do best in full sun, but will tolerate partial shade. It should be spaced about 12" apart, or 6-9" for very low-growing plants. You must remove old flower heads on a regular basis, or the plant may go out of bloom.

What are its primary problems?

Sometimes ageratum will lack uniform height The amount of bloom can vary from one plant to the next Southern blight may also be a problem

How do we propagate it?

Sow seeds indoors 6-8 weeks before last frost Seeding outside in warm soil will cause late bloom. Many people purchase transplants to get a jump on the season. Propagation is also accomplished by cuttings.

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Copyright, Department of Horticulture, Cornell University.