There is an incredible amount of diversity in plants’ ability to grow and adapt to their environment. While a cactus can grow without water for months, other plants need water every day. However, some types of soil, such as hydrophobic soil, are only suitable for specific plants.
Most plants can’t survive in hydrophobic soil for long periods of time. If a potted plant is surrounded by hydrophobic soil, the best solution to help the plant continue to grow is to rehydrate the soil carefully and remove its hydrophobic quality.
Understanding a plant’s water needs is essential for ensuring it’s able to grow and thrive. Let’s take a deeper look at what hydrophobic soil is, how it becomes hydrophobic, how it impacts your plant’s health, and how to rehydrate the soil.
Why Plants Can’t Grow in Hydrophobic Soil
Hydrophobic soil is best understood as a state of the soil, not a specific type. Hydrophobic soil can occur in any type of dirt. It means that the soil is unable to soak in water or other fluids and, instead, repels them.
Imagine pouring water on a paper towel versus on stone. The paper will absorb the water, while the stone will repel it. Hydrophobic soil acts the same way as stone.
This, of course, seems counterintuitive. When we walk out into a field after a rainy day, we might encounter wet grass and an occasional puddle, but, generally, water doesn’t just sit on the surface. The only time in which soil becomes hydrophobic is when certain wax-like particles build up in the soil for too long.
This wax, coming from plants and other organic matter, is designed to prevent plants from getting overwatered. Most of the time, these waxy particles break down or dissolve, but when they are allowed to build up over time, they stick to the water, preventing it from being absorbed by the soil. As a result, the water will either run off the top or bottom of a plant.
Plants Can’t Live in Hydrophobic Soil
Plants in hydrophobic soil might survive for a while, but, if left uncared for, they will die quickly.
Plants are able to grow through a process called photosynthesis. While humans and animals eat food that contains the calories that power our cells, plants need to produce their own energy. This is what the process of photosynthesis is.
Plants absorb carbon dioxide (CO2) and water (H2O) from the air and ground around them. Then, using sunlight, special cells in the plant break down the carbon dioxide and water in a chemical reaction that results in the creation of oxygen particles and glucose (C6H12O6). The plant then “eats” the glucose and uses its energy to grow, reproduce, and continue the process of photosynthesis.
If any key element is missing, the process of photosynthesis can’t occur. So, if a plant is trapped in hydrophobic soil, it will be able to survive until it has completely dried out all of the water in the soil. After this, it is only a matter of time until the plant becomes unable to perform photosynthesis and dies.
How Soil Becomes Hydrophobic
Soil only becomes hydrophobic when these waxy particles build up, why do they build up in the first place? In a nutshell, these particles are only able to accumulate when the soil is not watered frequently enough.
When plants are able to do their job, they draw nutrients from the soil around them (this is why compost is so good for soil). Some of the nutrients plants “eat” come from the very same wax they produce and release into the soil. However, if a plant does not receive enough water, it won’t able to absorb nutrients and break down these waxy particles. Over time, these waxy particles build up and actually prevent the plant from absorbing the water it needs to survive.
As a result, in extremely hot or low humidity conditions, where water is evaporated from the air and ground, soil rapidly dries out. Even if you water your plants every day, these conditions can make it so that your soil becomes hydrophobic. Of course, not watering your plants can also make the soil hydrophobic.
Luckily, hydrophobic soil is easy to identify. If you were to water your plant, and you see the water instantly roll off the top of the soil or pour right out of the bottom of a potted plant, then the soil is hydrophobic.
Sometimes the reason behind water not being absorbed by the soil is that the plant needs repotting. If you’re not sure if this is the real issue, you can confirm that your soil is hydrophobic by dropping just a few drops of water on the soil. If they don’t get absorbed right away, then you’re dealing with hydrophobic soil.
How to Rehydrate Hydrophobic Soil
To prevent your plant from dying due to hydrophobic soil, the best solution is to rehydrate the soil so that it is no longer hydrophobic. There are many ways to rehydrate the soil, so let’s take a deeper look at five of the best ones.
1. Submerge the Plant in Water
If your plant is potted, the best way to rehydrate the soil is to completely submerge the soil in water. Take the entire pot, with the plant inside, and hold it underwater. Initially, the pot will likely float, but as the water moves into the plant’s soil, the pot will sink. As you submerge the plant, you will see air bubbles coming up from the soil. Hold your plant underwater until the bubbles stop. Then, allow your plant to dry to normal levels and begin watering the plant as normal.
2. Set the Plant in a Tub of Water
If your plant is potted and is light enough to pick up, place the plant in a shallow container of water. The water should not be deep enough to cover the top of the plant’s soil. It should only be slightly above the bottom.
Allow the plant and soil to absorb water from the bottom until the soil is wet. Once the soil is moist, remove the plant and water at regular intervals to keep the soil moist.
3. Water the Plant With a Slow Trickle
If the plant is not potted or is too heavy to be lifted, you can use a slow trickle of water to help rehydrate the soil. The slow trickle gives the water enough time to, albeit slowly, become absorbed by the soil.
Set the water to a rate of two drops per second, and check every hour to see if the soil has remoistened. Though this will likely take a while, the water will eventually be absorbed and the soil will no longer be hydrophobic.
4. Let Rain Rehydrate the Soil
If you are forecasted to receive rain at some point in the near future, simply allow the rain to rehydrate the soil. Rain accomplishes the same “slow trickle” as described above, while also soaking all of the soil surrounding the hydrophobic soil.
While the hydrophobic soil might remain dry for a while, it can’t hold off the sheer amount of water that falls when raining. After the rain, be sure to water the plant frequently to prevent any damage that might have been done.
5. Add Preventative Soil Improvements
While soil improvements are not enough to prevent soil from becoming hydrophobic in its entirety, soil additives can help the soil retain water for longer. This will not rehydrate the soil if it is already hydrophobic but might prevent it in the future.
Hydrophobic soil can be a death sentence to most plants. While plants might be able to survive for a short amount of time in hydrophobic conditions, they can’t last forever.
If you encounter that your plant is surrounded by hydrophobic soil, take immediate steps to rehydrate the soil and allow the plant to recover from a lack of access to water. You can do this by submerging the pot in water for a while.
You could also check out my other article on why soil becomes hydrophobic here: Why Does Soil Become Hydrophobic? 4 Causes and Fixes