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Gardening From Southern California

by Gerald Burke
by Gerald Burke


Gerald Burke is a freelance travel and horticultural writer. He spent 35 years in the seed business, 30 of them with Burpee, and is a member of the Garden Writers Association and the North American Travel Journalists Association

April 15, 2007

Ageratum used to be called floss flower, and still is in some seed catalogs. The name arose because the flowers are little puff blooms densely clustered on low growing plants. Today’s ageratums that we grow in the garden are almost entirely the low growing, dwarf varieties, six to ten inches tall, which we use for borders and edgings. At one time taller varieties, 18 to 25 inches, were the most popular, and they were often used for bouquets, and some still are sold, including one named Blue Horizon Hybrid that’s said to be 30 inches tall.

Gardeners these days prefer low growing plants, especially in the west where low, ranch-style homes are the norm. So if you plant ageratum today, you’ll be looking for varieties such as Blue Danube, Hawaii, or one named Leilani Blue which is a little taller at around ten inches. Blue Danube has long been the best seller, and you’ll likely find it in the garden center or nursery as a started plant. Thompson and Morgan lists one named Purple Fields which I’ve never grown.

Ageratum’s popularity comes from the compactness of the plants, making it one of the best edging or border plants we grow in the garden. It’s not as wild and aggressive as alyssum sometimes is, takes a little more heat than lobelia, and will bloom all summer long and into the winter in mild areas. After its best flush of blooms, usually around late summer and early fall, the plants can be trimmed back to around three to four inches, and will start over again blooming for many more months in frost-free gardens.

Ageratum likes good soil and profits from regular feedings of a balanced fertilizer. It likes moist soil, but doesn’t like water standing around it, and doesn’t need any dead-heading, or removal of spent blooms. Disease and insects don’t bother ageratum, but snails will chew on tender, new foliage.

As a border ageratum makes an impressive sight in the garden, and does well in a medium sized container. Most varieties are blue, and there is a white variety, not often seen. Some varieties today are said to tend toward a little pink color and there must be lots of pink in ageratum, since it’s hard to take a color photograph of ageratum and have it look blue. Most of the pictures you see in catalogs have been color corrected to look as they do in nature.

You should find one or more varieties of ageratum as started plants in the nursery this month and through the summer. Finding them earlier is chancy, since nurserymen get nervous about losing plants to cold weather. But you can start from seed, outdoors as early as March, and under controlled conditions as early as January, and ageratum is easy to grow from seed. Catalogs list several, seed racks usually have one or two.

Where summers are very hot, as in is the inland area, ageratum will appreciate a littler shade during the hot part of the day. Along the coast it will tolerate full sun all day.

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