Rock mulch without a weed barrier?

Asked June 21, 2015, 9:04 PM EDT

We moved into a house a couple years ago that has planters with light-colored to white rock over landscape fabric. I have never had experience with landscape fabric or mulch before. I planted new landscape plants in the back planter last year and found moving rock, cutting holes in the fabric, planting plants, and re-covering with the rock to be quite labor intensive. We still get weeds and grass rooting into the weed/landscape fabric. We have other planters with rock that I want to add grasses, perennials, irises, bulbs, and ground cover to. It seems like a lot of holes will need to be cut in the fabric, so what is the point of having the fabric?

How is it possible to plant these kinds of plants with the fabric and rocks? Can we take the landscape fabric out and keep the rock? We don't want the expense of having the rock hauled away, but it is really difficult to do any kind of gardening with this fabric and rock mulch. Any suggestions?

Larimer County Colorado

4 Responses

Hi Jana,

The *best* thing to do for plants is to remove all rock and weed barrier and plant into the native soil and use an organic (wood) mulch near the plants. Research has found exactly what you're struggling with--that weeds tend to grow in the soil that settles in the rocks and the weed barrier is only effective for a short period of time. Further, the pores in the weed barrier can clog (from silt and soil) and actually prevent water from penetrating into the root system of plants. In addition, rock mulch can be very hot for some plants, leading to increased stress.

We (Extension) generally don't recommend using rock mulch (unless it's pea gravel for more succulent/xeric plants). And yes, while it's incredibly expensive to move, if plant health is your top priority, you would remove the fabric and the rocks and only use wood mulch following planting. The great thing about wood mulch is that you can continually replace it as it decomposes...a 2-4" thick layer throughout the landscape is recommended, though keep it 6" away from the base of plants.

Here is additional information on mulch from CSU Extension:

Thank you, Alison. Removing the rock entirely makes sense to me. We do have xeric and native plants and our new landscape plan calls for them as well. Our plan is to create a wildscape to attract birds. At least in most of the new area we only have to contend with sod removal. Hopefully, the rock removal won't be too cost prohibitive--otherwise we will just have to work with it.

The photo above shows wood mulch over the rock. Here are photos with the rock only.

Hi Jana,

I think with any landscaping project it's something you do over a period of time. Moving rock and really making the landscape "your own" could take several years. I would start small and focus on certain areas this summer...then make a plan for next summer, ultimately either removing all the rock or finding plants that prefer hot, dry conditions.

The fir is beautiful....I would simply add more wood mulch beneath it.