Understanding and Amending Our Soil
The role of the gardener is in being a soil builder. The soil is the foundation of the garden. Soil tilth or health determines the health of the plants. If you have healthy soil, you’ll have healthy plants, barring an extreme weather event. Of the seven Basic Gardening Principles, properly implementing this principle will bring you the most success in the garden.
The Texas Panhandle region consists of a wide range of soil types from caliche, to clay to sandy soils of varying grades. Our soil is alkaline (7 to 8.5 on the pH scale). The pH scale ranges from 0 to 14, 7 being neutral. Soil with the range of 0 to 6.9 are said to be acidic, alkaline soils range from 7.1 to 14). The ideal pH range is 6.5 – 6.8. Clay and caliche soil is often compacted, leaving us with poor air and water drainage. Sandy soil has too much drainage for most plants, lacking clay particles and organic matter to retain water and nutrients. Soil salinity is becoming an increasing problem due to excessive use of nitrogen fertilizers and irrigation. Our soils are naturally deficient in organic matter.
To determine your soil type and condition, have your soil tested. It is important to know what you are working with before you begin. County extension offices make available soil sample bags and instructions, or you may choose to use another soil lab (Texas Plant and Soil Lab, www.txplant-soillab.com, 956-383-0739), which also tests for organic content, in addition to the usual tests.
Two Remedies for Our Soil Conditions
There are two ways to garden in the Texas Panhandle region and you may decide to do one or both.
- Garden using natives and plants adapted to your soil. These are the plants to choose for a truly low maintenance, low water-use, and ecologically friendly garden.
- Amend the soil for the type of plants you wish to grow. Choose your favored medium and high water-use plants that meet our areas plant profile, with this exception of amended soil.
The first Basic Gardening Principle, Plan and Design, helps you to decide what kind of garden desires, design, style, and theory are in line with your personal gardening statement. You’ve outlined your plans and at least drawn a rough sketch of your landscape having drawn in structures, paths, turf areas, and beds. You have marked the areas according to high, medium and low water-use; you’ve divided your landscape into hydro-zones.
Before digging to amend soil or create new beds, consult with utility companies for the location of underground utilities to avoid severing them. Allow several days time for the utility companies to get back to you about the line locations.
Amending your soil for the type of plants is the critical factor in achieving a healthy, lower maintenance, lower water-use, and ecologically friendly garden. The extent to which you amend the soil depends on the type of plants you intend to grow. Adding humus (organic matter) to the soil will lower the soil pH, but it will not make our alkaline soil acidic. You will not change your basic soil composition (texture) of clay, sand or caliche, but you will improve it by adding organic matter.
As a general rule, plants that require high water-use are higher feeders and need the most compost/organic matter in the soil, 6 – 12 inches depending on existing soil quality. Medium water-use plants require a medium amount; 4 – 8 inches of compost/organic matter depending on existing soil quality, and low water-use plants require 2 - 6 inches, depending on soil quality. Caliches and sandy soils will require the higher amounts, depending on the extent of caliche and sand as a total component of the soil mix.
A mixture of composted plant and animal matter provides the widest range of nutrients and microbial life to the soil. Limit your use of composted manure to around three inches per year, and insure this is well blended into the top 8-12 inches of soil.
Amending for Native and Adaptables
For a truly low maintenance, low water-use, ecologically friendly garden, choose native and adaptable plants. Native plants and adaptables (plants that are native to other areas of the world with similar soil and climate conditions) will work in your soil, as it is. But they’ll look like what native plants look like unaided by the gardeners hand. In most cases, we desire a better look for our garden.
Minimal amending (up to 3 inches) for organic content and drainage is all that’s required to make them perform as worthy garden specimens. Many natives will thrive well with little additional amending for organic content in clay soil. Do not over amend with organic matter. Low water-use plants require good to sharp drainage. Some amending with inorganic materials may be needed for sharp drainage. Some dry land plants cannot live in a rich soil and will die.
Match your plants to their specific soil requirements, i.e. plants that require sandy conditions in sandy soil, plants that require clay soil in clay soil. A number of plants will live in caliche soil—few require it.
Amending for Medium and High Water-Use Plants
Most people are more familiar with medium and high water use plants, those that are more at home in the Midwest, East Coast, South, Pacific Northwest or England. Simply, it is because many gardeners in our region emigrated from those areas and that is what has been shipped to our nurseries and home improvement centers, up until recently. Not that there is anything wrong with them, for those areas. Some are old-fashioned plants, at least old favorites. Many are constantly touted in national magazines and garden TV programs. Only in rare moments of delight are we treated to the glories of plants that create a sense of place for our regional gardens.
It is only within the last decade that Southwest, adaptables and native plants have been introduced into the nursery trade, and slowly, I might add. It is still difficult to find the wide selection we should have.
High water-use plants are higher feeders and need the most compost/organic matter in the soil, 6 – 12 inches depending on existing soil quality. Medium water use plants require a medium amount, 4 – 8 inches of compost/organic matter depending on existing soil quality. High and medium water-use plants generally require average drainage. Adding the organic matter to soil will accomplish better drainage in heavy clay soil as well. However, organic matter needs to be replenished. It is helpful to add a new style inorganic amendment to help retain water and nutrients. The inorganic amendment should not need replenishment.
A mixture of composted plant and animal matter provides the widest range of nutrients and microbial life to the soil. Limit your use of composted manure to around three inches per year, and insure this is well blended into the top 8-12 inches of soil.
It is more difficult to easily grow high and medium water-use plants in caliche soil. Caliche soil is very poor and takes a great deal of amending to grow the traditional English garden plants. If you have caliche soil, consider gardening in raised beds up to 12 inches deep, filled with good quality topsoil and organic matter.
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