When we want to create useable space in our Northern California gardens, we often think of flat hardscape. This usually refers to level patios paved with stone, or brick, or concrete; or perhaps flat lawns for physical activity and play. The term ‘outdoor room’ has been used more and more often in the last several years when describing useable space in the garden. And it really is a good description. Creating a defined space outdoors that is accessible, attractive and can be used for one or many purposes equals home improvement. And it helps you to take advantage of living in the San Francisco Bay Area, where we can spend so much time outdoors. Hardscape patios and soft green lawns will likely always be part of the garden. But we’d like to make a case for gravel as a paving option with a lot of upsides.
One is environmental. Permeability is the rate at which water can flow through a material. While mortared stone, brick or concrete are impermeable, gravel, properly installed and maintained, can collect 50% of rainwater or more- so it is sinking into your land, not running off into storm drains or sewers. As Northern California is often in a state of drought, more permeability which allows water to soak back into the ground and prevent runoff is crucial. This is a small change you can make that positively affects our environment- and not every home improvement can make that claim.
Another is cost. Per square foot, other types of hardscape can cost 4 to 5 times as much as gravel. When we install gravel for a patio or path, we’re excavating down several inches, installing an edging to retain the gravel (a resin-based bendable board, metal, wood, or stone), installing a layer of base rock which is compacted for sturdiness, and finishing with 2-3” of gravel. Even with all these steps, gravel is significantly less expensive than a reinforced concrete slab, brick or stone patio. This logic also applies with driveways. Long expanses of hardscape for driveways can mean low permeability on your property, and with paving materials like a concrete slab or asphalt, significant cost.
The aesthetics, however, are often the main reason our clients choose gravel. There are many gravel options. You have choices in the color of materials, size of stones, and whether it is rounded or crushed. And perhaps the best attribute is the sound gravel makes when we walk across it. That crunch underfoot can define an edge or alert the user that they are entering a new space. It can even bring up nostalgic feelings of childhood trips to a lakeshore, a walk on one of our awesome California hiking trails, or a summer at camp. For those of you interested in container gardening or building a raised bed garden, surrounding your vegetables with gravel creates a permeable, low maintenance environment that is rustic and beautiful. It may not be hardscape in a traditional sense, but you can still push a wheelbarrow over it.
There are maintenance requirements with gravel that should be considered – gravel can move over time and may need to be replenished a few years after installation, and permeability is reduced over time as the material packs down. But it’s certainly worth considering for the Bay Area home; as a replacement of asphalt driveways, hardscape or lawns, or as a paving material for new paths or patios. Maybe you can’t hose it off like other types of hardscape . . . but ask any Japanese Tea Garden expert- raking a gravel pad, path or driveway is a physical activity that can be a calming in itself!