Surprising Effects of Soil Saturation

Keeping Outdoor Plants Healthy When There Is Too Much Rain

In 1972, when Albert Hammond and Mike Hazlewood wrote and composed the song, "It Never Rains in Southern California", I’ll bet they never thought for a moment that 50+ years later Southern California would have the wettest, rainiest season in—well, over 100 years. Yet, here we are chanting the classic nursery rhyme “Rain, rain, go away. Come again another day.”

Recently, California has been blessed with record breaking rain and snowpack. Every reservoir, underwater river, and well is full. In fact, nearly all lakes are filled to capacity and that’s before any of the snow has begun to melt.

While this is good news, it can be detrimental to our landscape plants. Excessive saturation poses a threat to weakening hillsides, smothering plants of oxygen—often to the point of killing them.

So we are going to explore the discipline behind saving our landscape in lieu of too much rain water.

I’m incredibly close to retrofitting my 14’ aluminum yacht into a miniature ark (just in case the rains don't subside any time soon). I’ve never seen so much precipitation in my life!

Back when I was a landscape contractor, we serviced everything from city-wide urban trees and greenery to the suburban patio plants of the Mrs. Jones-types of Sourthern California. Not once did we ever get a day off from work on account of excessive rain. When it did rain, it was always in the evening. By the time the sun rose each day, it was dry enough for us to at least do something—even if it was only possible to rake leaves for the first couple of hours.

These days, it’s a different story, with rainy days on-end. It stops for a mere bit before starting up again. In a way, that’s a good thing because it gives the soil a chance to slowly absorb the water. When that happens, it creates open pore space, allowing the soil to accept more water. Then, gravity is able to do its job and push water into the soil profile.

Did You Know?

A tree trunk typically always grows up and down. If a tree trunk is growing at an angle with the slope of the hill, it may mean the soil has shifted and that hill is at danger of giving way. Contact a tree specialist from the International Society of Arboriculture to ensure the hill is stable.

How Does Saturation Affect Soil?

Soil Composition Is Impacted. 

Porosity is contingent on the type of soil you have. When I was in college, one of my favorite class was called, “Soils”. For my senior project, I went to a local mission and took 12-inch soil samples. Each sample was taken 12 inches from the last over a 100-yard plot of land.

We started from an open field between the mission garden and its entrance. The field was home to an abandoned orchard. In many instances, the inconsistency of the minerals (sand, silt, clay, and organic matter) varied significantly from sample-to-sample.

Fast-forward to my professional landscaping days; I found it a chore to match a consistent soil composition across a single property. Albeit difficult, though, it’s not impossible to adjust. It just takes time, so you can’t be in a hurry .

Soil should be well-balanced when it comes to structure, with some sort of space between each soil element (sand/silt/clay/organic matter). Imagine for a moment a jar of marbles of different colors. Each marble represents a different soil particle. The space between each marble plays a significant role in the health of plants, as there needs to be room for roots to stretch out and for oxygen to travel through. When water fills up the pore spaces and doesn’t leave quickly, a series of unimaginable things can happen.

Soil May Become Waterlogged.

When water fills those pore spaces, it suffocates the roots. Each root has hairs that protect it as it grows. If the root hairs are damaged/smothered, the root will actually stop growing and it can take up to 6 weeks before the root hairs resume their role as protector. In the meantime, the plant suffers.

Nitrogen, phosphorous, and potassium aren’t the names of singers in a rock and roll band, they are the three major powerhouse nutrients needed by plants to survive. Plants technically only need 13 nutrients in total but will absorb more that that, given the opportunity. Have you ever thought of where those nutrients hang out before plant roots dine on them?

In simple terms, they attach themselves to the elements that make up soil. Now, imagine water, lots of water, bathing and passing by those minerals. As the water moves through the soil, those minerals are swept away. It's akin to a rushing river wiping out everything its path. Those nutrients are pushed further and further into the soil, past the reach of the roots. This leaching process will strip away the nutrients until there’s nothing left and your plants will suffer and eventually die without intervention.

Wipe those tears away because help is on the way!

Rainwater Awakens Seeds and Distributes Nitrogen.

...but not enough

Rainwater is nice, but after a healthy rain the first thing we notice is how clean and green everything is. Rainwater wakes up dormant seeds (eg: California Poppies) and lawns seem vibrant. But, if you wait just a few short days, you may notice those same lawns will have started to yellowing.

What’s happening?

Lawns are comprised of individual rejuvenating plants. Since rain comes from above, it can pick up elemental properties on its way down. As it moves through the atmosphere, it nabs nitrogen in a couple of different forms. This is great for our plants momentarily, but the nitrogen is brought in such miniscule amounts that it is used up quickly, leaving the plants wanting more. Meanwhile, the moisture may be smothering the lawn.

What about the rest of our landscape? Oh, it’s choking out the other plants too; we just see it in our lawns faster. Remember, the mention of root hairs taking around 6 weeks to grow back? Well, six weeks later, you will likely notice your landscape plants are starting to croak if you don't intervene. 

Fertilizer to the Rescue!

Fertilizer Supplements Important Nutrients.

Feeding your plants each month is essential but it’s imperative after a rain. When a plant is fed on a regular basis, the chances of it slipping into a rain-saturation-induced coma are lower because the fertilizer will be translocated into the plants.

There are Different Types of Fertilizer.

There are so many different ways to get the job done: liquid, water soluble, organic, and granular. Each one of these has their own set of strengths and weaknesses.

How to Deliver Fertilizer to Plants:

The way you deliver the fertilizer is equally important: hose end, broadcast, and in-line fertilizing injection, to name a few.

You’re not looking at cell phone power bars, you’re witnessing the power of directional watering and fertilizing. These chrysanthemums are a result of what happens when plants are fed regularly at the root zone, as opposed to simply getting water via a drip system. All of these plants have been over saturated and swamped by recent rains, but the ones on the right are supercharged!

Looking for a simple way to ensure your fertilizer is being delivered directly to where your plant needs it most? Root Quencher Jr. might just be the solution for you. It's perfect for many varieties of smaller shrubs and plants and enables both water and fertilizers to be delivered from within the soil, ensuring it goes directly to the plants root system.