Where to plant. Blue flowers are rather rare among annuals. This is one of the reasons for the great popularity of the Ageratum houstonianum (mexicanum). The flowers are dainty and feathery, often delightfully fragrant, and usually completely cover the plants. There are attractive dwarf, tufted plants as well as tall, upright growers. The dwarfer sorts appear to produce much more bloom, although the tall sorts furnish longer-stemmed cut flowers. The blue of the Ageratum combines well with pink in the garden. The white varieties are not as attractive as many of the other white annuals. A pink sort, cataloged as A. lasseauxi, is properly a species of Eupatorium. The growth is daintier but the flowers are not very showy. Height 6 to 24 inches.
GENERAL. The Ageratum is half-hardy. Seed should be sown in doors any time between January and April in order to get early bloom. When sown in the open ground (which should not be done before the soil is warm) the plants do not reach their full splendor until Fall.
In order that plants may be absolutely uniform for carpet bedding, they are generally propagated by cuttings. Bring stock plants into the greenhouse and take cuttings all through the Winter and early Spring. Such stock will be susceptible to white fly, which requires frequent fumigation with Calcium cyanide to keep it clean.
Keep the faded flowers picked, otherwise the plants will stop flowering and the clear blue effect will be marred.
AGERATUM Mexican Ageratum (Floss flower)
(A name first applied to an everlasting, meaning not growing old)