Plant species and soil type are two primary factors gardeners must consider when deciding which plant to grow. If you are considering growing Gaura, you should know that this plant thrives best in well-drained sandy soils. So, what if your garden has clay soil—can you still grow Gaura plants?
Gaura plants can grow in clay soil because their taproots penetrate compacted clay soil better than fibrous roots. However, clay has poor permeability, and its compactness can prevent Gaura from thriving. Amending clay soil with organic materials like compost will improve clay soil for Gaura growth.
If this response sounds complex, the rest of the article will break it down for you into simple gardening language. We’ll resolve the double puzzle of “why clay soil is not the best for growing Gaura” and “why Gaura will still grow in clay soil.” Let’s get straight to the task!
Why Clay Soil Is Not the Best Soil for Growing Gaura
If you research the information on the growth conditions for Gaura plants, you will discover that this plant grows well in well-drained sandy soils.
There are two core reasons why Gaura, and many other plants, grow well in sandy soil:
- Well-drained sandy soil has large pore spaces that allow water to drain quickly. Good drainage makes it perfect for Gaura because it prevents water logging and the consequent root rot. Besides, Gaura is a drought-resistant plant and does not need too much watering.
- Sandy soils provide a larger volume of soil for rooting depth. A deeper rooting depth means greater access to moisture and soil nutrients.
These qualities of sandy soil allude to the two core reasons why clay soil is not the best type of soil for growing Gaura:
Clay Soil Has Low Permeability
Soil permeability describes the ease with which moisture and air move through it. Soils with high permeability have larger pore spaces between soil particles. As such, they allow proper air passage and good moisture drainage through the soil.
On the other hand, low permeability soils have small pore spaces. As a result, they drain water slowly and are prone to water logging.
Clay soil is categorized among soil types with low permeability. These soils have less than 0.6 inches (1.5 cm) of water drainage in one hour. In comparison, sand has a high permeability of 6–20 inches (15–51 cm) of water drainage through the soil in an hour (source).
Referring to water requirements for Gaura, the plant grows well if the soil is well-drained and not soggy. Clay soil is poorly drained and favors water-logging, making it unfavorable for Gaura plant growth.
Clay Soil Acts as a Physical Constraint to Rooting Depth
Clay soil is prone to compaction and the formation of hard layers. For this reason, it is a physical constraint to root penetration in the soil (source).
Mature Gaura has deep roots that exploit a larger soil volume for moisture and nutrient absorption. Having deep roots is the main reason Gaura are known to thrive in poor soils and drought conditions.
As you can guess, the hardness and compactness of clay soil will not promote the best growth for Gaura plants. Even with this, however, it’s not completely impossible to grow Gaura plants in clay soil. Let’s discuss why.
Why Gaura Plants Can Still Grow in Clay Soil
Although it will thrive best in sandy soil, Gaura is tolerant to loam and clay soils and will still grow in these soil types. There are two reasons for this:
Gaura Plants Are Perennials With Taproots
The ability of plant roots to penetrate compacted clay soils largely depends on their diameter. Plants with wider taproots, such as Gaura, can penetrate layers of clay soil better than those with hairy roots.
Also, perennial plants tend to have better chances of penetrating tight clay soil than annuals. It’s because perennials stay in the ground longer than annuals and have more time to explore and adapt to the root environment around them.
Gaura is both a perennial and taproot plant. For this reason, it has better chances of navigating the clay soil they are planted in and finding a way of thriving in it.
Clay Permeability Can Be Improved With Soil Amendment
Clay soil is low in organic matter, making it compacted and hard for plant roots to penetrate. Besides, natural clay has tiny, flat particles that easily stick to each other, making air and moisture passage difficult.
It is not uncommon for gardeners to think adding sandy soil to clay soil will improve its permeability. But this is far from the truth; adding sand to clay creates a mixture whose texture is close to concrete (source).
Instead, you can improve clay soil permeability through soil amendment. Soil amendment implies adding material to soil to improve its physical properties, including permeability and porosity. Do not confuse soil amendment with mulching:
- Soil amendment is meant to improve soil properties. On the other hand, mulching is added to reduce moisture loss from the soil, prevent runoff, and control weed growth.
- Soil amendment implies thoroughly mixing organic or inorganic material with the soil. Mulch is left on the surface of the soil (source).
Clay soil is best amended with organic material. Those most recommended include:
- Yard clippings
- Wood chips
- Sphagnum peat
Inorganic materials include perlite, sand, pea gravel, vermiculite, and tire pieces.
When amending clay soil for planting Gaura, we recommend organic soil amendment materials. They are slow-release and will not overwhelm your Gaura with an overdose of nutrients. Remember that Gaura growth can be negatively affected by overly rich soil.
Gaura plants are a lovely addition to your garden landscape. You should consider them as a summer flowering plant that will not disappoint. If you have clay soil in your garden, it’s still possible to grow Gaura as long as you provide it with the right growing conditions.
You can trust the strong Gaura taproots to penetrate the hard and compact clay soil. Better still, you can use organic materials like lawn clippings, manure, and compost to amend clay soil for better Gaura growth.