An estimated 1,200 native flowering plant species grow in the Lower Rio Grande Valley, Texas. The Native Plant Project has selected a varied sampling of the native cacti and agaves, ground covers, and vines to be featured in
Plants native to the Lower Rio Grande Valley have advantages over plants brought in from elsewhere. Plants from this region have the genetic factors which ensure greater probability of survival. They are preadapted having evolved to tolerate local climatic extremes, local soils and local diseases and pests. Native plants have evolved with temperature and rainfall extremes and will require less water than exotic plants.
Using native plants helps conserve rarer species which are vanishing due to habitat clearing. Within the four-county (Cameron, Hidalgo, Starr and Willacy) Lower Rio Grande Valley area over 98% of the natural habitat has been converted or cleared for urban, agricultural, or industrial use. Establishing rare species in landscapes spreads out the individuals so one catastrophe cannot take out a species all at once and also provides a reserve seed source in the event the last individuals of a species are eradicated from natural habitat.
Some of our native cacti and agaves, ground covers, and vines are readily available from most nurseries in the Lower Rio Grande Valley. Rarer ones can be found only at the few nurseries specializing in Lower Rio Grande Valley natives. (See list inserted in handbook.) More and different native plants will become available if you demand them. The Native Plant Project will provide sources upon request; the availability of native plants changes as nurseries change their available selections due to demand.
Founded in 1982, the Native Plant Project's purpose is to protect and conserve the native plants (including endangered), habitats and environment of the Lower Rio Grande Valley and promote the use of local native plants in local landscapes. One method it uses is disseminating information about native plants and habitats. Its definition of a native plant is one indigenous to the four-county area of the Lower Rio Grande Valley.
The Native Plant Project encourages the protection of native plants through conserving and restoring native habitats in refuges, natural areas in parks, and wildlife management areas, and private sanctuaries. It works to protect both natural habitat and human-influenced environment. It encourages the conservation of native species through inclusion in local landscapings. The Native Plant Project works cooperatively with the U.S. Fish and Wildlife Service, Texas Natural Heritage Program, Texas Parks and Wildlife Department and many private organizations toward protecting Endangered Species, including those local natives imperiled but yet unlisted.
The Native Plant Project currently holds general meetings eight times per year. Members are advised of meetings, field trips and other activities through The Sabal, which conveys information on the native plants habitats, and the environment of the lower Rio Grande Valley. The Native Plant Project periodically updates and issues lists of endangered species of the Lower Rio Grande Valley and checklists of the woody plants.
The choice of a native ground cover, vine or cactus, like any other plant, should be dictated by landscaping need and the desired effect. Given the limits of purpose and site, finding a native plant which will handsomely fulfill every requirement is no problem. Once the choice is made, there remain only a few plant location and planting tips to be observed.
First, get your plants from a reputable, reliable nurseryman. DO NOT transplant from the wild, not only is this rarely successful, it diminishes our threatened natural plant and animal habitat. A healthy, vigorous looking small plant is much preferred over the large one, and smaller specimens suffer less transplant shock. With smaller plants, chances of survival and rapid growth are very high, they are cheaper, and within a year their size equals those which were initially 2 to 3 times larger.
Second, most native plants do well on most Valley soils. Poorly drained areas should be avoided or mounded for drainage and the vine or cacti planted on top of the mound. Also many of our native plants will grow on a site where a large portion of the soil near the root area is covered by blacktop or paving. Make sure the plants have plenty of growing space.
The best times to plant in the Lower Rio Grande Valley are late autumn (to allow for root establishment and dormancy before any freeze) and mid-February after danger of freezing has passed. Planting during the hotter months can be done but requires much more water, care and maintenance and is equally more stressful on the plant and you than planting during the cooler late-autumn through early-spring months.
A hole should be dug sufficiently deep and wide enough to hold the full root system. In very poor soils, it should be wider and deeper.
The depth of the top of the root system should NOT be lower than the top of the hole. It usually kills the plant when it is planted too deep. Remove the plant from the container. If roots are so numerous they are encircling the soil ball, cut the root ball with a sharp knife vertically to encourage the roots to grow outward. After setting the plant in the hole, soil should be added gradually, firming it at the base of the root ball before adding more. The goal is to bring the roots in close contact with the soil to eliminate air pockets.
The soil around the plants must be watered thoroughly after they are set in place. The frequency of watering depends on the type of soil and the amount of rainfall. Even native plants will require frequent watering during our hot summers.
The best advice for caring for a cactus is to mostly leave it alone. Most cultivated cacti die because they are overwatered. Cacti are adapted to conserve water, and they can survive very long periods of time without being watered. They are physiologically unable to handle frequent watering and, if overwatered, they will die of a fungal or bacterial rot. A good rule of thumb for cacti grown indoors is to only water them when it is raining outside. Cacti grown outdoors will survive without ever being watered.
Most of our small native cacti, contrary to what one would expect, will not do well if planted in full sun. These cacti occur naturally in the understory of the brush, in the partial shade provided by trees or shrubs. An ideal outdoors setting for these cacti is under a mesquite or huisache tree. An alternative is to plant them on the east side of a building where they will receive only morning sun. Most of our cacti will suffer if subjected to entire days of full sun.
Cactus should be grown only in a very well drained soil or potting mixture. If grown outdoors, they should be planted in a location in which the soil does not remain moist. Be sure that the location does not pond water after rains. If the cactus is to be cultivated in a container, use a very loose potting mix that will drain readily. A good mix contains a lot of sand. Placing a layer of small gravel in the bottom of the container will ensure adequate drainage and aeration. Do not dig up some soil from your yard and put that into the pot in which you are to grow your cactus. Use fertilizer very sparingly. For a small cactus in a container, a pinch of high phosphorous fertilizer once or twice a year will encourage blooming. A small amount of fertilizer can be applied around cactus grown outdoors, but only once or twice a year. Any fertilizer recommended for tomatoes, or for blooming plants, is suitable.
There is a suitable native vine or ground cover for every situation. When you've made a good match between site and plant, caring for vines and ground covers is easy.
Vines can be used to provide color and camouflage on vertical surfaces. They don't have to take up much ground space in your garden. Because they will climb, thought should be given to what will support them. Most vines will not damage masonry walls, though they will leave stains when removed. Unfortunately, vines can damage shingled roofs and wood-clad walls by trapping moisture against them and therefore should be trimmed below the eaves of most structures. A trellis provides an excellent way to place and keep a vine where you want it.
While most vines like to bloom in the sun, they also like to keep their feet in the shade. You can give your vine "cold feet" by mulching heavily after planting. Some people use a few big, flat rocks at the base of a vine for an attractive and durable mulch.
Native vines respond well to watering and fertilization. Water when the soil is dry to the touch and fertilize in the spring with a balanced fertilizer (i.e. 20N, 20P, 20K). Regular pruning to remove the terminal buds for the first few months after planting will encourage branch formation from the base of the plant. After establishment, simply prune to maintain your desired shape and size.
Regular pruning to remove the terminal buds for the first few months after planting will encourage branch formation from the base of the plant. After establishment, simply prune to maintain your desired shape and size.
Ground Covers should be selected with first consideration given to the amount of direct sunlight the location receives each day. Some ground covers, such as buffalograss, love full sun while others need the shade that trees and
shrubs naturally provide. Others, like frog-fruit, can and will grow anywhere.
Because ground covers are designed to spread by their roots or by stolons, heavy mulch will discourage their spreading, the ground cover's most desirable behavior. A small amount of light mulch is tolerable. It is absolutely essential to start with a weed free planting area. Weeds will continue to be your ground cover's worst enemy. Establishing native ground cover will require some natural weed control-just plan for a little pulling time.
Ground covers by nature don't require much maintenance. Most can be cut back a few times a year with a lawnmower set so that it just trims the plants. Fertilization with a nitrogen-rich fertilizer in the spring and fall will encourage growth.
Plant communities in the Lower Rio Grande Valley (LRGV) are part of the South Texas (or Rio Grande) Plains which constitute most of the Texas half of the Tamaulipan Biotic Province. The entire Lower Rio Grande Valley lies on the Gulf Coastal Plain which extends across the LRGV and Rio Grande to the Sierra Madre Oriental and its surrounding area. The western part of the LRGV (Falcon Woodland) is also the easternmost part of the shrub-dominated Chihuahuan Desert. Plains and brushland plants reach the LRGV from the north, and more eastern plants line the Rio Grande. Several plants have disconnected Trans-Pecos and LRGV distributions. Coastal plants reach the LRGV from north and south. Subtropical plants also lend their unique character to the LRGV's subtropical appearance.
Water availability, soil type, and temperatures are the predominant non-human determinants of the LRGV's unusually varied and unique vegetation communities and habitats. Five major plant areas include barrier island, coastal, riparian woodland, shrub lands (chaparrals), and sand plain grassland. Each of these five general areas consists of many diverse associations and habitats. The LRGV lacks perennial streams and few historic springs survive.
The four-county LRGV is enclosed by the Gulf of Mexico on the east, waterless Sand Plain containing La Sal Viejo and La Sal Del Ray on the north, and an arbitrary (county) line on the west between Falcon Reservoir (in the Chihuahuan Desert) and the Sand Plain. The Bordas Scarp in Starr County is the major component of relief. The Rio Grande (Rio Bravo) separates the Texan and Tamaulipan portions of the LRGV. The nonpolitical southern boundary is another waterless area between the Rio Grande and the Rio San Fernando. The area of Rio Grande Delta consists of the flood plain broadening eastward, including Cameron, Willacy, and southern Hidalgo Counties and a similar area in Tamaulipas.
The tree-life and water distribution somewhat characterize these five areas. The barrier islands lack trees and the few scattered shrubs never exceed one meter in height. The coastal communities have a few stunted Texas Ebony or Honey Mesquite trees on halophytic, shrub covered lomas. Freezes permitting, characteristic Black Mangrove shrubs grow near the coastal brackish waters or marshes. The riparian woodlands and palm jungles cover open or dense shrub layers which line the Rio Grande and its resacas. The dry shrublands consist of short trees and shrubs with taller trees around depressions or potholes. The Sand Plain and its bordering habitat lack trees except for isolated groupings surrounded by a sea of grass. Many shrubs in western and northern LRGV can shed leaves during drought stress and regrow them after rain.
Because of the little variation in temperature across the LRGV, our trees, shrubs and plants can be grown under a wide range of conditions with only minor modification of site and care. Riverbank-adapted plants require more water than will other natives. Where necessary, this handbook includes such site modifications in hope of improving success when using one of the LRGV native plants in your landscape.
Ajilvsgi, Geyata. 1991. Wildflowers of Texas, Shearer Publishing: Fredericksburg, TX.
Everitt, J. H. and D. L. Drawe. 1993. Trees, Shrubs & Cacti of South Texas. Texas Tech Univ. Press: Lubbock.
Everitt, J. H., D. L. Drawe and R. I. Lonard. 1999. Field Guide to the Broad-Leaved Herbaceous Plants of South Texas. Texas Tech University Press: Lubbock.
Native Plant Project. 1994. Native Trees of the Lower Rio Grande Valley. Texas. Landscape Uses and Identification. Native Plant Project, Edinburg.
Native Plant Project. 1996. Native Shrubs of the Lower Rio Grande Valley. Texas. Landscape Uses and Identification. Native Plant Project, Edinburg.
Neck, R. W. 1996. A Field Guide to the Butterflies of Texas. Gulf Publishing Co.: Houston.
Ogden, Scott. 1998. The Moonlit Garden. Taylor Publishing Co.: Dallas.
Pyle, R. M. 1981. The Audubon Society Field Guide to North American Butterflies. Alfred A. Knopf: New York.
Richardson, A. 1995. Plants of the Rio Grande Delta. University of Texas Press: Austin.
Wasowski, Sally, with Andy Wasowski. 1988. Native Texas Plants: Landscaping Region by Region. Texas Monthly Press, Austin.
The Native Plant Project currently holds general meetings eight times per year. Members are advised of meetings, field trips, and other activities through The Sabal, which conveys information on the native plants, habitats, and the environment of the Lower Rio Grande Valley, Texas.The Native Plant Project periodically updates and issues lists of endangered species of the Lower Rio Grande Valley and checklists of its woody plants.
Native Plant Project
P. O. Box 2742
San Juan, TX 78589
The Native Plant Project wishes to thank its Board members for producing this handbook.
Valley Nature Center
301 South Border Avenue
P.O. Box 8125
Weslaco, TX 78596