By Molly Day
All the Dirt on Gardening
Northwestern Oklahoma and West Texas soil, like New Mexico’s Chihuahuan Desert, was formed 220 to 270 million years ago when the area was under water. These locations have islands of gypsum, dolomite and shale deposits from when they were ocean floor.
Gypsum (hydrated calcium sulfate), is the primary ingredient in plaster of Paris and wallboard — a difficult, low-nutrient, environment for plant life. The seeds of most weeds and non-native plants cannot grow in it.
Among the native plants, there are a few called “true gypsophiles” that grow only on gypsum outcrops and gypsum-rich soil. (For more scientific information about gypsophiles, see tiny.cc/r4cmnw at Oberlin College.)
Gypsum-loving plants include: Bougainvillea, angel trumpet, bicolor mustard, fiddleleaf, sandwort, prickly poppy, blanket flowers, prairie dropseed, and several native daisies, sunflowers and asters.
In September, the Oklahoma Native Plant Society held its annual meeting at the University of Central Oklahoma’s Selman Living Lab in the Cimarron Gypsum Hills (www.uco.edu/cms/sll/). Dr. Gloria Caddell, biology department chair, guided the 40 attendees on an all-day walk through the hills, identifying plants in sand, soil and rocks.
The plants on the 135-acre Selman Living Laboratory include: Bluestem, Indian grass, switch grass, grama grasses, buffalo grass, sand sage, sand plum, sumacs, hackberries, elms, cottonwood, chittamwood, willow, prickly pear, small cacti, various mosses, ferns, liverworts, and a large variety of flowering annuals and perennials. Wetland plants on the site include cattails, rushes, sedges, water cress and various algae. Photos of each plant on the site are at http://www.uco.edu/cms/sll/species.asp.
Many of our common rock garden plants are gypsophiles and one of the best known is baby’s breath. Gypsophila paniculata is tall and the creeping variety is gypsophila repens. Gypsum-loving plants thrive in alkaline or sweet soil.
The native territory for the 100 gypsophila includes dry, stony, slopes, dry stone walls and sandy steppes. Gypsophilas can be annual, semi-evergreen perennial, woody, mat forming or cushions.
Rosy veil, or gypsophila rosenscleier, tolerates winter moisture better than most of the other varieties. Each plant forms an 18-inch mound that can mature at 20 inches tall. It is a semi-evergreen perennial in zones 4 to 9 and has double, pale-pink flowers in the summer.
Gypsophila elegans is annual baby’s breath with tall branching stems and dozens of star-shaped flowers. Bright rose has rose-pink flowers, bristol fairy has double white flowers, and Carminea has deep pink flowers.
Start annual gypsophila seeds in the ground in the spring; winter-plant perennial varieties in a 60-degree environment or in a cold frame in spring. Seed-starting materials for gypsophila contain sand, gravel or crushed stone and the plants require sunny, well-drained locations.
Home gardening expert Walter Reeves (www.walterreeves.com) recommends the addition of gypsum to soften clay soil. Reeves says that if your seedlings have a hard time coming up through crusty soil, apply 5 pounds of gypsum per 100 square feet for 3 years.
Gypsum adds calcium to the soil, encouraging root growth and fruit production, though not all experts agree about its value since most soils have enough calcium. Even Reeves points out that adding several inches of compost is more likely to create growth improvement than the addition of gypsum.
You can join the Oklahoma Native Plant Society ($15) to find out about future events. The ONPS membership form, current newsletter, and meeting information can be found at www.oknativeplants.org. Their next Indoor-Outing will be held Feb. 2 at the Tulsa Garden Center, 2435 S Peoria Ave.
OSU Fact Sheet HLA-6410 at http://goo.gl/K3EF6, recommends baby’s breath for Oklahoma gardens.
Gypsophila seeds are easy to find at Harris Seeds (harrisseeds.com), Thompson & Morgan (tmseeds.com), and Burpee Seeds (burpee.com). Gypsophila diseases include crown rot from wet soil.