Express-News Weekly Column

Saturday, May 10, 2003

Submitted by Calvin Finch, Ph.D., Manager, Conservation Division, Water Resources & Conservation Department, SAWS, and Horticulturist

 

BUTTERFLY PLANTS

           

If you have been listening to any of the radio gardening shows in the last few days, you know that most are recruiting listeners for the Community Challenge program to support the new Butterfly Exhibit at the San Antonio Zoo. If the participants overall save 5% on their water use for five months this summer compared to an average over the last three years, SAWS will donate $5 per participant to the Zoo. Participants will also receive gift certificates to the sponsoring nurseries.

 

 

Butterflies can be attracted to your yard or even patio by selecting the right plants. Many of the plants are good xeriscape plants. 

 

Lantana is attractive to both butterflies and hummingbirds. The tiny blooms form tennis ball-size clusters of flowers in gold, yellow, lavender, red, orange, pink, and crème. The blooms are shallow enough for butterflies to reach the nectar and bountiful enough for the hummingbirds to be interested in the flowers.

Lantanas prosper in full sun. Most varieties will bloom more or less steadily over the summer if they are skimmed with the string mower every five or six weeks.

The haircut stimulates a new flush of bloom. ‘New Gold’ is an aggressive spreader that makes a good summer groundcover in full sun. Spreading lavender lantana (Lantana montevidensis) is not as aggressive as ‘New Gold’ but also makes a good groundcover. Lavender lantana seems to have some shade tolerance and more cold tolerance than other lantanas. It will bloom all winter some years and does well in dappled morning or afternoon sun. Lantana montevidensis comes in a white version as well. Both are excellent container plants. A pot of this lantana on the patio will bring the butterflies in for easy viewing.

            Ruellia is also called Mexican petunia. The tall aggressive version loves full sun. There are several dwarf versions, ‘Katy’ (blue flowers), ‘Bonita’ (pink flowers), and ‘Blue Shade’ (blue flowers) that do well in light shade. All versions are popular with butterflies. Use the dwarf varieties for low-water-use groundcovers. If you use the full size Mexican petunia, be prepared to control it unless you have plenty of space.

Blooming plants are the source of nectar for adult butterflies but foliage plants for the larvae (caterpillars) must also be available to maximize the butterfly population in your landscape. Passion vine flowers are very attractive and provide nectar to butterflies, but the plant is probably even more valuable as a source of foliage for caterpillars. Once the vine is established it does not require supplemental irrigation. Plant it in full or partial sun on a fence or trellis. Remember that caterpillars are sensitive to insecticides. If you use BT for webworms or tomato hornworms be careful to limit the spray to the target plants.

Pentas, like passionvine, provide both nectar and foliage. Its red, pink, white, or violet flowers is one of the favorite nectar sources for many species of butterflies. It is also a favorite hornworm food source. Unfortunately, if the hornworm strips the foliage from your penta, it will not bloom well. If you see any damage, find the culprit and move the critter to another site. There is usually only one caterpillar per plant. Pentas are good container plants and tolerate some shade. They require more water than the other plants but are worth it if butterflies are your goal.                    

There are many annual flowers that make excellent butterfly plants. Some like coreopsis, larkspur, cosmos, sunflowers, moss roses, purslane, and vincas qualify as low-water-use plants. Plant them in full sun for blooms in a progression from early spring through late fall. The coreopsis, larkspur and sunflowers will reseed themselves every year if the seed can reach the soil (no sod or mulch).

Zinnias are also great butterfly plants. The variety ‘Dreamland’ is available in transplants in the San Antonio area. If you plant it in early summer, it will reseed itself through the summer and into the autumn. The reseeded zinnias are not as colorful or well formed as the ‘Dreamlands’, but the butterflies love them even more than the nursery selection.

Zinnias, moss rose, and purslane all do well in containers.

            Purple coneflowers and fall asters are perennials that provide nectar to butterflies in the autumn. Both require full sun. Coneflowers bloom over a relatively long period. The fall asters do not bloom for a long period, but they are spectacular for two or three weeks. The coneflower form clumps 18 inches in diameter. The asters form a mound 2 feet tall and 5 feet in diameter. Both require full sun.