hydrophobic soilDroughts, heat waves, and poor watering can result in a dry and water repellent soil, also known as hydrophobic soil. If you have this problem, you will notice that water runs off the surface and form puddles. This soil condition can be a problem for gardeners who end up with improperly hydrated plants.

Any soil type regardless of the composition can become water resistant if allowed to become bone dry. Sandy loam or even soil mixtures rich with organic matter can repel water due to lack of moisture. I’ve come across this problem when starting a garden in a previously uncultivated area. In raised beds or pots that are well drained, soil can also dry out and develop hydrophobia. The good news is that this garden dilemma can be fixed.

How to Reintroduce Moisture in a Hydrophobic Soil?

The best way to deal with hydrophobic soil is to avoid it from happening in the first place. A regular watering schedule is a key to a successful garden. In warmer areas, integrating a well-aged organic compost into the soil and a mulch layer is important for moisture retention. However, when starting a garden, potting a plant, or building a new raised bed, gardeners are not always blessed with perfect conditions. Furthermore, mother nature can also play a huge part.  A drought or heatwave can evaporate moisture faster than a gardener can keep up with.  In any case, check out the following methods to fix a hydrophobic soil.

Soil Wetting Agents

Hydrophobic soilIf your aim is to re-wet soil as quickly as possible, you can use a soil wetting agent (surfactant). A soil wetting agent lowers the surface tension of water so that it can be absorbed into the soil. Some recommend soap as a wetting agent but be careful when using household products as they can contain harmful chemicals. Wetting agents are available in garden sections, but it can also be a DIY project. One thing to keep in mind is that not all wetting agents are suited for organic gardening because they contain petroleum derivatives and alcohol. To stay organic, you can opt for a DIY agar-gar wetting agent. Agar-agar is a gelling product that is made from seaweed and algae. You can find it in health food shops or on Amazon. For an agar-agar wetting agent recipe, check out this blog on How to Beat Hydrophobia.

Building a Healthy Soil

Hydrophobic soilHealthy soil contains organic matter that retains moisture longer even in extreme climates or weather conditions. If you’re dealing with a hydrophobic soil, you can introduce organic matter to help with aeration, water infiltration, and retention. To learn about different types of organic amendments, click on this link. Just keep in mind that poorly decomposed organic matter such as leaf litter can release waxy residue that can build up and make soil water repellant [1].

My Garden Experience

When I encounter dry soil in my in-ground garden, I typically amend homemade compost to the top 3-6” inches. Then I water the area real slow for a very long time. If you have a drip system, run it real slow for 8-24 hours for water to penetrate deep.

hydrophobic soilI also just finished setting up a new raised bed and the garden soil I bought in bulk is extremely dry. When I tested its soil composition, it’s a little sandy. However, there is plenty of organic matter that should balance it.

Unfortunately, it’s been really dry in Southern California, and heat waves have sucked the moisture out of everything. The first time I watered my new raised bed, water overflowed instead of being absorbed.

To avoid overflow during my second attempt, I ran the water on low. I also used a garden fork to loosen the soil and provide space for water to infiltrate. This method worked to some extent, and I will have to continue watering this way for a few days to a couple of weeks.

I’ve personally never used agar-agar as a wetting agent, so I just ordered a bag from Amazon to test this method on my raised bed. I will keep you posted on how my experiment turns out. If you want to read more about how other gardener deal with hydrophobic soil, visit this forum.