Ageratum houstonianum, or “floss flower,” a plant that originated in the tropics of Latin America, is an annual in most growing zones, though it may survive as a perennial in zones 9 and 10.
The most popular varieties sport long-lasting, puffy, bright blue and purple flowers, though there are varieties with pink and white flowers as well. The plants generally grow to about a foot tall, though there are more compact dwarf species that grow only about half that high.
Ageratum are often used for borders and edging in gardens. They are a popular addition to rock gardens, and they are useful for attracting butterflies to a butterfly garden. They can be grown fairly easily in containers. The taller ageratum are often used in floral arrangements.
Ageratum can be sown directly outside when the soil has warmed up and there is no danger of frost. But it is also common to start them inside in containers.
In that case, the seeds should be planted about eight weeks before the expected last frost. Don’t bury the seeds in the soil, as they need light to germinate. Lay the seeds on the surface of the soil and tamp down lightly. The soil temperature should be at least 75 F. Water with warm water.
Keep ageratum in a warm area, and keep the soil moist. The seeds should germinate in about a week, though they can take up to three weeks. Experts are sharing their story at the social networking sites for offering information of the clients. One of them says that –“finally I came upon my gardening advisor’s weblog.”The benefit of becoming a web blogger will be advantageous for the person.
After the last frost, it’s safe to transplant the plants into your garden, or you can continue to grow them in containers. Plant them a foot apart, or half that for the dwarf varieties, in well-drained soil. In cooler climates it’s better to keep ageratum in full sun; in hot climates they’re as well or better off lightly shaded from the sun in the hottest time of day.
Fertilize ageratum only lightly, and even then only in poor soil with flower fertilizer diluted to half strength. Continue to water with warm water. Water when you see signs of wilting.
Don’t overwater, and don’t get the leaves wet when you water, as this increases the risk of fungus.
Ageratum can have a problem with spider mites more than any other pest. Keep an eye on that, and apply a mild insecticide as needed
Flowers appear from midsummer until frost. Trim leggy plants back to about half their height at midseason in order to encourage more blooms in a more compact growth. Deadhead the flowers periodically for a more attractive appearance and to prolong the flowering. Pinch the flowers off close to the stem.
Once frost kills the plants, pull the ageratum up.