David Robson: Baptisia adds burst of color

Many native perennial flowering plants make great landscape plants. Goldenrod, given a bad rap because it flowers at the same time as allergy-producing ragweed, can brighten up the fall garden with yellow when all you have are mums.

Many native asters do the same. Throw in the bluish-purple ironweed, and you have a great flower garden.

The only problem is that most of the natives that stand out tend to bloom in August, September and October.

Fortunately, most isn’t all. There are other great bloomers in the spring.

That brings us to Baptisia, a native that bursts forth in the spring, sending up spikes of blue-to-purple flowers that require little fuss.

The Perennial Plant Association chose Baptisia as the Plant of 2010.

Baptisia, called false indigo, wild indigo, indigo week, rattleweed or rattlebrush (more on that later), is a member of the bean family, which means you never really have to fertilize it. It makes its own food through nodules on the roots, taking nitrogen from the air and converting it to a form the plant can use.

Additionally, the plant is adapted to just about any soil, from clay to sand. Like most plants, it will thrive in a silty loam with lots of organic matter added to the soil.

To pronounce the plant name correctly, emphasize the second syllable: bap-TEEZ-ee-uh. The scientific name Baptisia australis comes from the Greek “Bapto,” meaning to dip, which refers to the fact the plant was used to make cloth dyes. You can still use the flowers to achieve a good bluish-purple color.

The name “australis” does not refer to Australia in the strict sense, but because it means “southern.”

Flower stalks usually reach about 3 to 4 feet high, with the clump eventually reaching about the same diameter. You may occasionally want to stake or put a plant ring around young clumps or around those in windy areas. The plants won’t break, but they will bend and lie on the ground. With plants that tall, they are best located in the back of the flower bed or middle of the border.

This is one of the few garden flowers that has a tap root, so moving it often isn’t viable or practical.

Baptisia foliage is more of a gray-green instead of a marigold or petunia green. Without the flowers, the plant softens many of the coarse spring and summer perennial foliage.

Most of the 12-inch flower heads are bluish-purple or purplish-blue depending on environmental conditions and genetics, though there are white cultivar forms. There are yellow Baptisia, but most are in other species. All do well in our gardens.

Once the plant flowers, a seed pod forms from each flower that looks at first like a broad pea pod. It elongates and slowly starts to turn a grayish-black. You can end up with 25 or more pods on one stalk.

Interestingly enough, the pods don’t pop like lots of other flowers until late fall.

Instead, the seeds become loose within the pod and start to rattle — hence the common names rattleweed or rattlebrush. When the settlers were traversing the Midwest, they’d come across the plant, hear the rattle and cut specimens to give to their toddlers. Fortunately, the plant isn’t poisonous, as most toddlers probably stuck seed pods in their mouths.

The pods last long as a dried cut stem to add to fall arrangements.

In the garden, a strong breeze will make the pods rattle, which might be scary if you grew up in the deep Southwest with certain snakes.

Full sun is ideal. However, if you have partial shade, the clump will survive and bloom; it just might not grow as tall or as wide. Using a plant ring helps in the shade, as the stems tend to reach for the sun and aren’t as sturdy as their full-sun counterparts.

Baptisia isn’t preferred by deer or rabbits. Not that they might not try it, but it’s not appealing, and they’ll soon leave the plant alone.

In fact, the plant has few insect or disease problems. Baptisia will rot if continually flooded, so don’t locate it next to a downspout or in a ditch.

Baptisia is easily propagated by seeds, though you will need to lightly sand the seed coat or use your nail file to allow it to absorb water. Or wait. Eventually, the coat will dissolve, and the germination process can start. Over the years, you may find small plants popping up here and there in the garden, especially if you don’t remove the pods in the fall.

David Robson is a horticulture educator for the University of Illinois Extension. For more gardening information or for your local extension unit office, go to www.extension.uiuc.edu/mg. This column is the opinion of the writer and not of the newspaper.