River rocks are an attractive addition to the landscape — as long as they are appropriately sized and serve a functional purpose.
By Brad Wier and Dana Nichols
“I’m considering removing all the grass and replacing it with rock. But SAWS doesn’t offer a coupon for river rock. Why can’t I just put in gravel and be done with it?”
It’s a question we get a lot in SAWS Conservation. The simplest answer is that aggregates like pea gravel and river rock are already so widely used as a watersaver that they require no special incentive or coupons. But even though stone requires no water, there are a few cautions to keep in mind about using it as a default ground cover:
1) It tends to absorb and reflect heat, which can be a stress to both plants and people.
2) It doesn’t retain moisture as efficiently as mulch.
3) It accumulates dust, leaves, refuse and weeds -- so it's not as maintenance-free you might assume.
4) Smaller aggregates like pea gravel and crushed granite tend to wash off in rain, clogging city storm sewers.
A proper xeriscape always strives to include an even balance of grass or groundcovers, landscaping beds and pervious hardscape like rock and patios. So where is the proper place for river rock? As long as it’s at least two inches in diameter so it won't wash away, it’s great for creating texture in the landscape — accents, a base for walkways and edging for landscape beds.
It also has a functional use: providing drainage when needed, like in side yards around AC condensers and in dry streambeds.
Don’t be discouraged if you prefer the smooth look of stone. But leave some room for hardy trees, shrubs and perennials to add beauty, birds and butterflies to your landscape. Remember to put rock in its place — just not every place.