Summertime blues
Two cool varieties added to Texas Superstar list

June 30, 2005
NANCY KRAMER
Victoria County Master Gardener

Blue cape plumbago and vitex, or Texas lilac, have recently been added to the growing list of plants recommended by the executive board of the Texas A&M Superstar program. These two Texas Superstars brighten the landscape with their indigo blooms. Birds, butterflies and bees love them both, and hummingbirds are attracted to vitex. Both are deer resistant. These superstars have been tested for durability and tolerance for the hot summers of our area. They are both very hardy, disease and pest resistant, and require minimal care.

The Texas Superstar program is an educational and marketing campaign which Texas A&M started in 1989, with input on plant sustainability from Aggie horticulturists, nursery professionals, growers, seed company representatives, county horticulturists, arboretum and botanical garden representatives, horticultural writers and landscape designers.

Decisions to award Superstar status are primarily based upon observations made at replicated plots and demonstration trials across the state or even by recommendations from other Southern states.

Plumbago auriculata, or cape plumbago, produces beautiful, phlox-like clusters of blue flowers all summer long until frost. The name "plumbago," or leadwort, comes from "plumbum," Latin for lead, because the plant was believed to be a cure for lead poisoning at one time. While it is native to South Africa it is well adapted to our long, humid summers. A prolific bloomer, cape plumbago, prefers full sun, but will bloom considerably well in shade.

The rich, bluer cultivar, Royal Cape, is darker than the species plant and doesn't fade in the heat and dryness of summer, but is not as cold hardy. A white-blooming variety is a less prolific bloomer.

Like all Texas Superstars, this tender, perennial shrub is easily grown in most soil types with good drainage. Reaching heights of 3-4 feet and up to 5-feet wide, it responds well to pruning. In fact, it is a bit rambling if not pruned. There are quite a few planted out at the Master Gardener Victoria Educational Gardens, and they are trimmed frequently to keep them within their bounds and to encourage re-blooming since they bloom on new wood.

Plumbago will freeze back with the first hard freeze, but don't despair or be tempted to dig it out as growth will return in spring. If the temperatures do not get that cold, it is advisable to prune it back to about 1/3 its size. It is helpful to add fertilizer when growth starts in early spring.

Plumbago can be used in informal hedges, but should be planted with winter annuals or other evergreen plants so you won't have a bare spot during winter. They are versatile enough to be planted with Texas natives, roses or tropicals, such as hibiscus or bougainvillea. I especially like them combined with Belinda's dream roses or some of my favorite red and white flowers in a patriotic grouping.

Cape plumbago make good container plants and add a cool, refreshing splash of color around pools or patios. They look great cascading from a hanging basket.

The other new Texas superstar plant is the vitex agnus-castus, also known as the Texas lilac or the chaste tree. A couple other common names are hemp tree and monk's pepper.

A native of China and India, it is not new at all, being naturalized in America since around 1670. For hot Texas landscapes, vitex has been the best shrub to mimic lilacs, which will only grow in cool regions. The chaste tree, or monk's pepper, got its name because the dried fruit, which looks like pepper, was touted during the 6th century as the herb that helped monks maintain their vow of chastity.

Vitex grows and blooms best in full sun in soil that drains well. They can grow to 25 feet, but the most common size is 12-15 feet. Vitex are so tough and love heat so much so that they have been planted in the highway medians by the Texas Highway Department and in areas getting only natural water.

I discovered six beautiful chaste trees along the walking trail in Riverside Park below the Victoria Rose Garden and wondered how old they are and how much care they are given, if any. They must be the new and improved variety, because the flower spikes are about 8 inches long. The old vitex, that people have seen around for years, have small spikes of flowers that were pale lilac, mauve, off-white or light pink and were not very desirable.

Horticulturists now have identified and tested improved varieties such as Montrose Purple, LeCompte and Shoal Creek, with 8- to 12-inch flower spikes. These varieties are all marketed under the name Texas lilac vitex. I went right out in search of these new varieties of the vitex after I read a news release and found some at the Home Depot stores in South Texas with the Texas Superstar label, Texas lilac. The beautiful flowers are big, fragrant and long lasting.

After several weeks of beauty the flower racemes produce fruit with dark seeds resembling pepper, which could produce a mutant seedling population with less desirable blooms. This can be avoided by deadheading, which can be challenging, since vitex is extremely fast growing. They will in turn bloom again within a month.

Jerry Parsons, a professor at Texas A & M University and a Texas Cooperative Extension horticulturist with more than 30 years' experience in South Central Texas, recently presented a program on these superstars at the Victoria Builders Association Home Products show. He recommends that the entire vitex plant be cut back to the ground every winter. A recent article I read said that in an area with a large deer population, the bucks will prune the vitex back while rubbing their antlers on the branches. The article can be found at:

http://aggie-horticulture.tamu.edu/cemap/plumbago/plumbago.html More information can be found at these sites also:

http://www.plantanswers.com/plumbago_best.htm or http://www.plantanswers.com/vitex.htm

Parsons encourages keeping vitex a small shrub size and not letting them get any taller than 6 feet so that the spent flowers can be reached for pruning. Fertilizing after pruning will encourage new growth and re-blooming. The flowers will form on the new wood, such as with the plumbago, perennial hibiscus, esperanza and hamelia or firebush. In cooler areas of Texas, these plants freeze to the ground and grow back in the spring. Therefore, to encourage better blooming in our area, cutting these plants to the ground each year is helpful. They will continue to bloom well into the hottest months of the year and toward the end of the summer.

We should all encourage pollinators, such as bees, butterflies, and hummingbirds to visit our gardens and landscapes, and it's always great to sit out and watch and listen to other birds that are attracted to dense bushy growth. So why not plant vitex and plumbago, two of the best "blues" and keep the "blues" away?