How does your garden grow?
Soil amendments needed to grow plants successfully in sandy soil
May 23, 2014
by Julie Moritz/Victoria County Master Gardener
Edited by Charla Borchers Leon/Victoria County Master Gardener
PHOTOS BY JULIE MORITZ/VICTORIA COUNTY MASTER GARDENER
This native pink prairie gentian, commonly called pink star or meadow pink, will self-sow and develop into large colonies of pink stars. It exists along with various wild coreopsis, flax, paint brush and swamp thistle flowers that thrive in the dry, sandy soils of the Texas Gulf Coast.
Oleanders thrive in direct sun and amended sandy soil. They have been planted on the 5-acre slice of coastal prairie as a privacy hedge between the road and home site. While they do have a utilitarian purpose, they also provide height and color to the coastal landscape.
Just beginning to flower, this free-standing bear grass yucca is a mostly long, sword-like leafy plant that produces elongated flower spikes rising from the center as its leaves mature. It can provide sensational white blooms for an otherwise natural, green setting in sandy soil.
The aloe nobilis, also known as gold tooth aloe, is a rosette-forming succulent that suckers profusely and flowers in red-orange on a stalk. This plant happily thrives in a sunny corner bed with amended, sandy soil.
My husband and I live on sandy soil. The desire to retire close to bay fishing waters put us on 5 acres of undeveloped property in Calhoun County 2 miles inland. The land looked fine to us with natural live oaks, yaupons, lots of motts (patches of brush on the prairie) and wildflowers. According to the United States Department of Agriculture General Soil Map of Texas, we are on the Gulf Coast Saline Prairie. One of our Houston friends dubbed it "the wilderness."
Characteristics of sand
Water and nutrients stored in soil are the main source of supplement for plants. Sand is a soil that is coarse in texture, light in color and can be strongly alkaline. This means it drains well, does not hold nutrients well and has a very high pH. Our pH is 8.8, far above the neutral 7.0 level that keeps plant nutrients available. Also, this drains-easily characteristic can translate to "dries out." It is clear that soil amendments are needed to garden in it.
Our main goal with our turf was to keep the sand down where it belongs in the ground, not blowing all over the place. The existing Bermuda grass was not enough. We selected St. Augustine to sod around our boat barn; Bermuda grass seed was added for the large areas.
Soil preparation was the addition of at least 2 inches of nutrient-rich top soil. After the initial watering to start the growth, maintenance has been twice yearly fertilization and mowing. We keep the Bermuda grass high at 3 inches since we do not water. Our selections have proven to work for us. The St. Augustine does fine in the barn's shade. The Bermuda grass drought and salt tolerance make it a good choice.
With 5 acres of "yard" we don't mind weeds. They add green. However, nutsedge and sand burr are the exception. They love sand. We have found that applying an herbicide specifically intended for nutsedge, according to the directions, works. We follow the application with a sweep of the affected area to clean up the burrs. We attach an old blanket to the back of our four-wheeler and drag it over the infested area to gather burrs.
Our landscaping consists mainly of existing trees and motts. I cleared from the underneath to encourage height and used fertilizer spikes to feed. During the drought, we watered the drip line to help them along.
We did plant a privacy hedge of oleanders between the road and the house. These have grown very well in the amended sandy soil. Maintenance is drip-line watering as needed and spring fertilizing, mulching and trimming as needed.
It should be no surprise that tough, drought-tolerant blooming plants are the best sources for flowers in our landscape.
Our two front "flower" beds are primarily cacti, succulents and bear grass yucca. Again the soil was amended with nutrient-rich potting soil before any planting began. We used white rocks in the beds as they are suggested to keep the weeds to a minimum. Weeding and occasional watering during drought conditions was our goal for easy maintenance.
I added a side bed of the Texas Superstar Cape plumbago this spring with amended soil. I have high hopes for this toughly tested plant that can survive in almost any Texas setting.
Wildflowers are my favorite. I made an effort to plant some Texas bluebonnets in unamended soil several years ago. I gathered dried seeds from pods that had burst open and scarified the seeds before shallow planting them in the sand. I watered for about a week and then turned that job over to Mother Nature.
First year, no bluebonnets. I still had hope that the following year something would appear. Nothing. Now, three years later, I saw two anemic Texas bluebonnets about 300 yards away from my planting.
This spring, I planted a packet of hardy flower seed in amended soil. I thought this should work. Overnight, an ant bed appeared. They thought they were delicious. So now, I'm content with the various wildflowers that grow naturally in my landscape. I have learned not to mess with Mother Nature.
In conclusion, the key to gardening in sandy soil is amendment. Then, regular maintenance is mandatory; fertilizer is necessary as the sand does not hold nutrients as well as finer textured soils do. Also, watering is required if plants are not drought tolerant.
We moved to "the wilderness" for peace, quiet and space. By limiting our gardening in sandy soil to the turf, one privacy hedge and a few landscape beds, we are content. And isn't that what gardening is all about?
The Gardeners' Dirt is written by members of the Victoria County Master Gardener Association, an educational outreach of Texas AgriLife Extension - Victoria County. Mail your questions in care of the Advocate, P.O. Box 1518, Victoria, TX 77901; or firstname.lastname@example.org, or comment on this column.
SUCCESSFULL GARDENING IN SANDY SOIL
• Soil amendment is key.
• Regular maintenance is mandatory.
• Fertilizer is necessary.
• Watering is required if plants are not drought-tolerant.
Sand (course textured soils)
• Better internal drainage
• Less ability to hold and store water and nutrients
• Requires more frequent watering
Clay soils (fine textured soils)
• Poor internal drainage (water stands longer)
• Holds water and nutrients longer
• Requires less frequent watering
Loam (mix of sand, silt and/or clay)
• Typically has adequate internal drainage
• Typically has good water and nutrient holding capacity
• Ideal for gardening and landscape