How To Fix Cracked Garden Beds After A Scorching Hot Summer

If your garden has received plenty of rain or you’ve watered faithfully during a drought, but plants are still struggling, your soil may be the problem. Some types of soil and environmental conditions repel water, leaving plant roots and cells depleted of moisture. Let’s take a deeper look at why your soil looks cracked and dusty and what you can do to rehydrate the soil and improve the situation.

Understanding the Causes of Cracked and Dusty Soil

Soil that repels or will not absorb and hold water is called hydrophobic soil. The condition can occur after long periods of drought or a wildfire, when soil particles become coated with waxy substances as organic matter decomposes.

The composition of the soil is a key factor in how well it absorbs water. Areas affected by wildfires or those with sandy soil are more prone to hydrophobia than loam or clay. Another example is common potting soil that contains peat moss. Peat moss retains water, but once it dries out, it is very difficult to rehydrate. That’s why water will flow quickly out of a container’s drainage hole but leave a plant’s root system dry.

Assessing Your Soil Condition

If the wilted condition of your plants after watering hasn’t given you a heads-up, you can easily test the hydrophobicity of the soil. Place a drop of water directly on the soil in your garden or container plant. Set the timer on your phone and watch how long it takes the water to be absorbed. If the water is still sitting on the surface after one minute, the soil is hydrophobic. Other signs include:

• Cracks in the soil.
• A handful of soil feels dry and dusty and does not form a ball when squeezed.
• Water runs off quickly without being absorbed into the soil.
• The soil pulls away from the sides of a container-grown plant.

To assess soil moisture more accurately, you can purchase soil moisture meters that measure the water content in the soil. These meters often use electrical conductivity or tensiometer tubes that measure the suction exerted by the soil on the water, which indicates the soil moisture available to plants.

Immediate Solutions for Rehydrating Soil

While not a long-term solution, a wetting agent can be mixed into hydrophobic soil to break down waxy substances that repel water. Commercial products may be labeled as water retainers or penetrants. The effectiveness can vary depending on the type of soil and the level of hydrophobicity. Follow the label directions for application.

Studies are underway on the use of agar-agar or gelatin (unflavored) to enhance the water-holding capacity of soil. These powdered hydrogels can be mixed into the soil to act like sponges, absorbing and retaining water.

Most commercial wetting agents contain surfactants similar to those in dishwashing liquids and laundry detergents. Surfactants are molecules with hydrophilic (water-loving) and hydrophobic (water-repelling) ends, which interact with water and soil particles, aiding water infiltration and distribution in soil. A DIY method to rehydrate soil is to add several drops of liquid dishwashing soap to a full watering can and slowly apply it to the soil. Use a mild, non-antibacterial, and preferably biodegradable dish soap. The soap helps break the soil’s surface tension and allows water to be absorbed.

Whether you use a commercial or DIY wetting agent to adjust the absorbency of soil, you must follow up with proper watering techniques to ensure the water penetrates deeply. Apply irrigation slowly, water in early morning when temperatures are lower, and water in longer sessions rather than daily short bursts.

Long-term Strategies for Soil Improvement

Improve the structure of the soil by working in organic matter to improve moisture retention by enhancing the soil structure. Organic matter, such as well-rotted manure or compost, will help restart the microbial activity needed to break down the waxy substances that prevent water absorption and retention. Add the compost and dig it into the soil.

Once you have amended the soil, add mulch to the soil surface to help slow down moisture evaporation. Organic mulch (wood chips, grass clippings, compost, pine straw) is better than inorganic mulch (stone, gravel, rubber) because, as it absorbs moisture and begins to break down, it adds more microorganisms to the soil.

To help the soil that supports turfgrasses absorb water more easily, remove thatch and aerate lawns using a manual or powered aerator to create small holes. Aerate when the grass is actively growing, typically in the spring or fall for cool-season grasses.

Enhancing Soil Biology

In addition to working compost into the soil, you can amend and improve the health of your soil by regularly introducing microorganisms. Mix up some compost tea or use fish emulsion once a week to water non-edible plants. Remember, microbes need water to thrive, so maintain adequate moisture by monitoring soil moisture and watering deeply as needed.

Special Considerations for Potted Plants

Potted plants dry out quickly, and soil can easily become hydrophobic if left dry for too long. It will crack, pull away from the sides of the container, and refuse to absorb water.

To rescue a plant quickly, place the container in a larger tub of water, making sure the soil’s surface is fully submerged. You will see bubbles of air being released as the water saturates the soil. Let it soak for 10 to 15 minutes or until the bubbles stop. Remove the pot and let the water drain away. Top the soil with a new layer of potting soil or compost to restore the soil volume until you can repot the plant with fresh potting soil.

Preventive Measures

To help prevent hydrophobic soil, regularly add organic matter to your garden beds. Monitor the soil moisture level during both dry and rainy seasons and maintain a consistent watering routine adjusted seasonally. Regularly taking soil samples and having them tested will also help you maintain nutrient-rich soil.