Primetime Newspapers
By Calvin Finch, PhD, SAWS Conservation Director, and Horticulturist
Week of October 11, 2004

TIME TO PLANT MOST WILDFLOWERS

 

Wildflowers are good xeriscape plants.  They require no supplemental irrigation to make their show.  Wildflowers are also important nectar plants for butterflies and hummingbirds.  Many selections, including bluebonnets, are usually not eaten by the deer.

If you have a sunny vacant lot or field that dries out every year so that there is bare soil in late summer, it is probably a good wildflower site.  Wildflower seed must have soil contact to germinate.  It does not need to be buried, but if the seed is insulated from the soil by sod or organic material, the planting will not be successful.  The seedbed does not need to be prepared as long as the seed can reach soil but a discing or raking before seed is applied helps increase germination success.

Bluebonnets are the Texas state flower and relatively easy to naturalize in the San Antonio area.  The only things that reduce the performance of bluebonnets are too much water, weeds and occasionally caterpillars.  Excessive rains over a four or five week period in late winter or excessive irrigation will rot bluebonnets.  The excessive moisture will also determine growth of the tall weeds that share bluebonnet growing space.  The weeds grow up over the bluebonnets and the flowers are invisible in the field.  The tendency to rot with excessive moisture is combated by selecting a well-drained planting site and by eliminating any irrigation.  If you notice small caterpillars stripping the foliage in early spring, a quick Bt spray will work or you can leave the planting to the whims of nature.  Many of the plants will survive and there is always next year.  If you are planting bluebonnets, consider the reds, maroons and whites in addition to the blues.  Plant the rarer colors in isolated patches to preserve the color longer.  Blue is dominant and gradually takes over most good sites as the plants hybridize each year.

            Coreopsis is available in many forms.  My favorite is the yellow flowered version called “tickseed” by most folks.  On a good site (“good” for tickseed means heavy soil that dries out every year), the naturalized coreopsis will provide a solid blanket of yellow in early spring.  Butterflies are everywhere fluttering from flower to flower.  Tickseed is a good companion plant with bluebonnets because it is more tolerant of rainy spells and prospers in wetter years.

Purple coneflower is a late blooming wildflower that does well in our area.  It is also a perennial that will return in late summer each year if it is seeded in full sun on well-drained soil.  I use them in my cut flower garden for the large purple blooms.  They are also a favorite butterfly nectar source and the seed eating birds like the dry flower heads. 

            One of the problems with growing wildflowers is that to have them naturalize (reseed themselves) requires that they be allowed to mature.  A maturing wildflower is not very attractive.  A field of wildflowers maturing seed heads is a weedy field to most folks.  There is no color or order.  The fields sometimes attract the attention of neighbors and code compliance officers. One way to minimize the weedy field look is to plan to have wildflowers blooming year round. 

Most mixes include bluebonnets, verbena and coreopsis for the early bloom.  Mexican hat, poppies and primrose bloom a little later.  Purple coneflower, black-eyed susan and Salvia coccinea do a good job of decorating late summer.  The mid-summer gap is the real problem.  Cosmos can fill the gap.  Cosmos are not native but they seem well adapted to South Texas summers and are easy to plant.  The key to cosmos culture is timing the seed application.  Cosmos are very cold sensitive.  Unlike bluebonnets and the other wildflowers, cosmos do not germinate in the autumn, develop roots all winter and grow large in the spring.  Plant cosmos in April for blooms throughout the summer and into the autumn.  Cosmos are aggressive reseeders.  The usual pattern is to have a bloom flush, a brown period while the new seedlings emerge and then another bloom period.  The process speeds up and is more attractive if the old plants are mowed on a rotation pattern.  One strip is in full bloom while the next strip is growing new plants.

            For more information on wildflowers visit plantanswers.com.