How To Use Gravel To Help Your Landscaping Projects With Drainage

Are you becoming concerned about water pooling around your property? Are you noticing puddles of rainwater in your garden, around the edges of the driveway or patio, or — worse — at the perimeter of the home's foundation? If so, your landscape needs improved drainage solutions to manage the water. If you allow poor drainage to go unchecked, you'll invite a number of issues to your home and garden. Most crucially, rainwater build-up can cause cracks in the foundation of the house. In the garden, pooling water can kill your plants by waterlogging their root systems. Fortunately, there's a ubiquitous and inexpensive element that can help you solve many of the drainage-related headaches in your landscape: gravel.

Gravel is a highly effective drainage medium because the voids between the stones allow water to flow down as it's pulled by gravity. This characteristic makes gravel an excellent tool for draining rainwater from locations where it would otherwise collect in the landscape. For example, you can use gravel as a surface material in driveways, patios, and walkways. This technique helps prevent overflow in your yard, as any rainwater that falls on these surfaces will effectively trickle down and get absorbed by the soil below. In garden beds, gravel helps water flow away from the roots of your plants. In French drains, gravel enables water to enter a perforated pipe and escape to a drainage point while keeping out debris that could clog the pipe. We explore all of these gravel drainage uses in greater detail below.

When used on landscaping elements like driveways, patios, walkways, and in garden beds, gravel lets rainwater seep through gradually, at which point it gets absorbed by the soil beneath. Compare this with a solid, impermeable surface, like concrete — if you have a concrete driveway, walkway, or patio, any rainwater will flow down its surface quickly and pool around its perimeter. This runoff can dump large quantities of water on your lawn and next to adjacent structures. Even if the water flows off the property, it will cause erosion by washing away soil from the adjacent areas, and carry contaminants — like your lawn fertilizer — down to nearby watersheds. By soaking up the rainwater, gravel prevents this erosion-causing runoff, waterway contamination, and pooling. Gravel used in these applications is usually large in size, with stones that measure ½- to 1-inch. This size prevents the gravel from becoming compacted and prevents water absorption.

Gravel also keeps water from saturating soil in the garden during periods of excessive rain. If you place gravel on the surface of the beds, the permeable layer will allow water to trickle down to the ground at a slower rate that's easier for the soil to absorb well. Conversely, you can lay a gravel base at the bottom of garden beds. This way, any rainwater trapped in the soil will have an escape route — one that helps it drain away from the plants' roots. These seemingly simple mechanisms let your garden plants get all the moisture they need without becoming waterlogged and suffering from the ensuing (and often fatal) consequences, like root rot.

Gravel is an indispensable component in French drains. These subsurface drainage systems collect rainwater in areas where it accumulates heavily and channels it away to an acceptable drainage location. For example, if the landscape surrounding your home lends itself well to pooling rainwater, a French drain can just be the tool you need to keep the area dry.

In simple terms, French drains comprise a trench, a layer of gravel, and a perforated pipe inside. Invented in the mid-19th century, French drains were meant to help farmers divert rainwater away from livestock pens. In those early days, they generally comprised gravel shoveled into a ditch, and the perforated pipes were introduced later to improve their efficiency.

French drains work by absorbing groundwater from the landscape and keeping it from reaching a vulnerable structure, like a foundation. As water saturates soil, it undergoes a great deal of hydrostatic pressure. This pressure causes the soil to travel sideways and downward through the ground. As it reaches the French drain, the water moves through the gravel and fills the trench. If the pipe at the bottom of the trench is installed holes-down, it will start picking up the water right away. If the pipes' holes face upward, the water will have to fill the trench to the top of the pipe before it's carried away. Once the water enters the pipe, it flows away from the vulnerable structure the drain is protecting, helped by gravity and often a sump pump.