By: Lorenzo Rossi and Michael G. Cook – Texas A&M AgriLife Extension Service
It is an exciting time for Texas wine, as the bustling industry is producing reds full of character, crisp and clean whites, and uniquely complex blends that are gaining international recognition. With its diverse 1,300 soil series, rainfall ranging from <10 to 60 inches a year, and over 8 AVAs (with three in progress), the Lone Star State challenges winemakers to think outside the box. From Tempranillo to Tannat, Mourvèdre, and Sagrantino, Texas wines are winning over critics and wine lovers alike. But what makes these wines so special? While climate, grape variety, and winemaking techniques all play a role, the secret to great wine is also in the soil.
A Personal Journey from Florida to Texas Wine Country
My path into viticulture has been shaped by years of hands-on experience in both soil and fruit crop research. Before moving to Texas, I spent much of my career studying citrus production and root biology in Florida. In my time there I worked closely with commercial growers facing the realities of sandy soils, extreme weather, and persistent disease pressures. I saw how poor soil management could weaken an entire grove and how targeted soil improvements could significantly boost soil quality and tree productivity.
Now, in my new role at Texas A&M University, I am shifting my focus to viticulture, where soil remains a key factor in producing high-quality crops. Growing grapes in Texas presents more curve balls to the mix than Florida: from the Florida-like climate and soils of South Texas and the Gulf Coast to the fractured limestone in the Hill Country, to the arid and high elevation of the High Plains where red clay and caliche lays under a layer of sand. Each region requires a different approach to soil management, and my background in soil research can help me understand how growers can make the most of their land. My goal is to aid Texas grape growers who want to refine their soil management practices enhancing vine physiology, improving fruit quality, to ultimately produce better wines.
Why Soil Matters in Winemaking
The ideal vineyard soils strike a balance: loamy to sandy-loam textures promote proper drainage while retaining enough moisture for consistent water and nutrient uptake. A soil pH between 5.5 and 7.5 optimizes nutrient absorption, and calcium-rich substrates like fractured limestone improve root penetration. High-quality soils also contain 2–3% organic matter, which supports diverse microbial communities that enhance nutrient cycling and naturally improve disease resistance.
To measure soil quality, vineyard growers should conduct regular soil testing, including pH, nutrient levels (such as nitrogen, phosphorus, and potassium), organic matter content, and soil texture. Tools like a soil probe or auger can be used to collect samples from various vineyard locations. Testing for soil compaction and microbial activity can also provide valuable insights into the soil characteristics. Additionally, monitoring drainage, water retention, and aeration can help identify any issues that may affect vine growth.
When grapes are grown in soils with limiting conditions, the grower must implement a range of best management practices to improve a soil characteristic while maximizing yield and quality over the vineyard’s lifespan. These may include amending soil with organic matter and adjusting pH levels to enhance nutrient availability. When soils are well-optimized, the quality potential of the grapes increase, potentially leading to the production of richer and more complex wines.
Texas’ Unique Wine Regions
Texas vineyards span multiple American Viticultural Areas (AVAs) and regions, each with unique soil characteristics that shape the wines they produce. Understanding these soil differences allows growers to fine-tune their management practices and maximize vine health and fruit quality.
Texas High Plains AVA: The Texas High Plains is responsible for nearly 70% of the state’s grape production. Sitting at an elevation of 3,000 to 4,000 feet, this region has sandy loam soils with red clay subsoil rich in calcium carbonate. These well-drained soils allow growers to manage vigor through irrigation. The manipulation of irrigation in these soils can also be used to alter fruit chemistry flavor and berry size, leading to greater concentration of compounds in fruit. Cover crops and organic composts can help retain moisture and improve soil biodiversity, which may provide additional benefits to grape quality. Wines from this region are known for their structure and depth, including medium bodied to full reds like Tempranillo and Cabernet Sauvignon.
Texoma AVA: Located along the Texas-Oklahoma border, the Texoma AVA holds historical significance as the home of T.V. Munson, the horticulturist who helped save European vineyards from the phylloxera epidemic in the 19th century. The soils here range from reddish clay loam to black “gumbo” clay and fertile sandy loam, offering diverse opportunities for vineyard management. Techniques like soil aeration, addition of organic matter such as compost, and controlled irrigation help maximize grape quality. White wines, like Viognier, Blanc du Bois, and the newly planted Picpoul blanc do especially well here.
Texas Hill Country, Fredericksburg in the Texas Hill Country, and Bell Mountain AVAs: Perhaps the region most often associated with Texas wine, the Hill Country AVAs, feature limestone-rich soils that are usually quite shallow, which can add a distinctive minerality to these wines. Scattered alluvial deposits of deeper loams along the Pedernales flood plain offer improved soil conditions. The high pH of these soils affects how vines take in nutrients; this makes proper soil management essential. This region is famous for Mediterranean-style grapes like Tempranillo, Sangiovese, and Mourvèdre, which thrive in the well-drained yet nutrient-challenged soils. By adding organic amendments and using chelated fertilizers growers can boost fertility and water retention.
Escondido Valley AVA: A small but promising AVA in West Texas, Escondido Valley has deep sandy loam soils with excellent drainage. The warm days and cool nights allow grapes like Cabernet Sauvignon and Merlot to ripen slowly, resulting in wines with balanced acidity and layered flavors. Here, growers can focus on moisture retention techniques like cover cropping and organic mulching to maintain soil quality in the arid climate.
Texas Davis Mountains AVA: Nestled in a rugged, high-altitude landscape, the Davis Mountains AVA boasts volcanic-derived soils with rich mineral content. These well-drained soils, combined with cooler nighttime temperatures, create an ideal environment for growing Syrah and other Rhône varieties. Organic matter enrichment, careful water management, and biodiversity conservation help vineyards thrive in this unique terroir.
Mesilla Valley AVA: Stretching into New Mexico, the Mesilla Valley AVA is one of Texas’ driest and warmest grape-growing regions. Its sandy and silty soils are highly permeable, requiring precise irrigation to prevent excessive water loss. However, these conditions are perfect for growing heat-loving grapes like Zinfandel, Syrah, and Tempranillo. The grapes, soil, and climate work together to create wines with rich flavors and smooth textures.
Gulf Coast and Lower Brazos Valley wine regions: The Gulf Coast, stretching from Houston to the Mexican border, has a warm, humid sub-tropical climate that is known for producing grape varieties like Blanc du Bois, Black Spanish (Lenoir), and, more recently, Blanc du Soleil. Because of high rainfall (and high fertility of some soils), vines have extreme vigor here. With salinity potentially being an issue along the coastline itself. The sandy loam and alluvial soils provide good drainage but require added organic matter to maintain fertility. Because of the high humidity, proper canopy management and soil aeration are essential to prevent disease and ensure high-quality fruit.
Enhancing Soil Quality for Better Wine
Regardless of location, improving soil composition can be a game-changer for Texas viticulture. Some key strategies include increasing organic matter through compost, mulches, and cover crops. Compost can come from pomace and local cattle or poultry farms (when properly composted). Compost helps enhance soil structure. Texas soils generally have very low organic matter, ranging from 0-1%, but the target range for organic matter is 2-3%. However, excessive additions can cause issues, so it’s important to apply compost in moderation. Mulches are another option, though they are less commonly used due to costs and labor demands.
Cover crops can be an effective strategy for improv ing soil composition. In Texas, growers can apply seed in the row middles in September or October and terminate them in May or June. Several cover crop options are available, including clover, triticale, blue gramma, oats, wheat, annual rye, ryegrass, turnip, daikon radish, mustard, and chicory. These cover crops could enhance soil structure, increase microbial diversity, and improve water retention.
The Soil-Wine Connection
A vineyard’s soil is the foundation for our vines, acting as a water and nutrient bank. Good quality soils that provide the necessary resources for the vines can promote more resilient growth, helping the vines endure Texas’ climate challenges. This can lead to more consistent yields and improved fruit quality over time. Additionally, well-managed soils may help reduce the need for certain chemical inputs, contributing to a more sustainable and environmentally friendly approach for Texas wine production. While soil characteristics play an important role in overall vine vigor, they can also support the vine’s ability to respond to both biotic and abiotic stresses, potentially making them better equipped to cope with certain diseases.
As I continue my journey in Texas viticulture, I am excited to work alongside local growers to improve soil characteristics and elevate the quality of Texas wines. Just as I learned in Florida’s citrus industry, soil can play an important role in the overall vine physiology. With the right soil care, Texas wines will continue to flourish and gain the recognition they deserve.
Feel free to reach out to me at l.rossi@tamu.edu for collaboration or discussions.