Conquering Dogged Cattails

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By Scott Aker
Special to The Washington Post
Thursday, October 2, 2008

Q Cattails are taking over my pond. Is there a safe, chemical way to kill these things?

A Herbicides are an option but only those labeled for control of weeds in wetlands, such as Rodeo. Applied now, late in the growing season, herbicides are more effective than if sprayed earlier in the season or when the plants have begun to prepare for winter dormancy.

Even if you get rid of the cattails, be prepared for their return. The seeds, with their fluffy tails, are blown great distances on the wind and are certain to germinate wherever there is continuously saturated soil or shallow water. Some pond owners modify their ponds by dredging the margins to make them deeper at the water's edge. Cattails won't establish in water more than 18 to 24 inches deep. Cattails also will not grow well in shade, so you could plant trees at the pond's edge to limit their spread.

I have been trying to grow Texas bluebonnets in Washington with limited success. I got one plant to survive three years but with sparse flowers and seed production. Is it possible to get a good stand of these beautiful wildflowers this far north?

Texas bluebonnets are one of the most lovely of all the native lupines. Five or more species of lupines share the common name, but only Lupinus texensis is readily available in seed racks.

Like most lupines, bluebonnets grow in cool weather. They naturally germinate in autumn in their native range, grow throughout the winter and bloom in spring. In our climate, they should be planted in late September or early October. The seeds have a hard coat, and you can hasten germination by nicking them with a nail clipper and soaking the seeds overnight before planting. Keep the seedbed moist until they germinate. Throughout autumn and early winter, the plants will grow a rosette of leaves that hugs the soil surface. Don't be alarmed if the plants look wilted during the winter; this is only a response to cold weather.

It is conceivable that if left in place and adequately pollinated, your Texas bluebonnet might have set some seed. But the seed might not have fully matured and therefore won't be viable. Incidentally, it is unusual for Texas bluebonnets to live longer than a single year. Like foxgloves, snapdragons and other winter annuals, it is conceivable that it may persist, particularly if not allowed to set seed. The other possibility is that you may have a different species. Some of the species of bluebonnet native to Texas are actually short-lived perennials.

Scott Aker is a horticulturist at the U.S. National Arboretum.


© 2008 The Washington Post Company

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