“Rock Gardens”

Surface boulder_COS_LAH_7750In the year we’ve lived in our new house, the first on the block, we’ve gained a number of neighbors. Now that the growing season is officially underway, these new yards are being landscaped. And I’m reminded all over again of why, back in 2000, I signed up to become a master gardener.

You see, when we first moved here, I quickly noticed that the major landscaping theme was composed of lawns, junipers, and rocks. Lots of rocks. I became a master gardener volunteer to help people grow more attractive and interesting landscapes. But in spite of all that advice, apparently nothing has changed in the last 23 years.

With a few notable exceptions, our neighborhood is beginning to look like it belongs in Phoenix, not Colorado. Yes, there are plenty of lovely green lawns, in the front yards as well as the back. (I suspect that in many cases, the only traffic they’ll get is when they’re mowed.) However, the majority of the landscapes are comprised of a few shrubs surrounded by vast expanses of rock mulch.

With today’s focus on xeriscaping (often confused with zero-scaping), I can understand why people would “plant” rocks. They don’t require watering. (Neither does cement—at least the HOA won’t let us pave our yards.) I believe these homeowners expect their inanimate landscapes to be low maintenance as well. And yes, rocks do not need to be mowed. However….

Rock mulch_COS_LAH_7745Right now these rock “gardens” look neat and weed-free. This is because they’re new. Wait until the next gully-washer (or the kid next door) starts rearranging things. The red rocks will be in with the gray rocks, the smooth rocks will mix with the sharp rocks, and all of them will be on the sidewalks and in the street. Are the homeowners going to go out and separate the colors again? (And yes, our downpours are quite capable of moving rocks. I’ve seen it happen.)

Rock mulch_COS_LAH_7744But how about weeds? Our HOA stipulates the use of landscape fabric under all mulches. (We did not do this. Shhh… don’t tell.) This is intended to keep the weed seeds under the mulch from germinating. However, those are not the seeds that cause problems; without sunlight, they’ll continue to stay happily dormant. It’s the seeds that blow in on top of the mulch that germinate and grow. And when you go to yank those plants out, their roots will be enmeshed with the fabric underneath, making them nearly impossible to pull. Sure, you can spray weed killer on them, and they’ll die. Now you have dead weeds decorating your rocks. They still need to be pulled.

Rocks have other drawbacks as well. They reflect heat back at the plants, making an inhospitable microclimate that will fry tender leaves. They’ll never break down to enrich the soil, and believe me, the subsurface soil the builders left behind needs all the help it can get. They don’t encourage earthworms. And there’s no way those owners are going to move the rocks and cut holes in the fabric so they can plant pretty annuals and perennials. Can you tell I’m not a fan?

Dry creek bed_COS_LAH_7736I need to mention that not all rock mulches are bad. Dry creek beds demand rocks. Riprap provides effective erosion control on steep slopes. Pea gravel and other similar-sized mulches make a lovely seedbed for many xeric annuals and perennials.  However, the universal use of landscape fabric tell me that there won’t be flowers reseeding here.

Not all the rocks in the neighborhood are in the form of mulches. Larger, decorative boulders are also popular. In this case, rocks are lovely. We probably spent as much on boulders as we did on shrubs. They anchor the landscape in winter, when the plants are dormant, and provide an attractive backdrop to manzanitas and other mountain species. However, there are some things to keep in mind when using boulders if you want them to look like they belong.

Probably the most important is to bury them, perhaps halfway or even more. I know, you just spent a wad to get a really big rock, and now you’re going to hide half of it in the ground? Yup, that exactly right. Go look at a mountain. Are the rocks sticking up, totally exposed? No, they’re not. You want you rocks to look as if they’ve always been there, and the best way to do that is to copy Mother Nature. If you don’t believe me, compare these photos and decide for yourself:

There’s a house down the street where they placed their boulders on top of their grass. I guess they like it that way, but I think it looks rather odd. And think about mowing that lawn—they’re going to have to go around the rocks, then come back and use a string-trimmer. What a hassle!

I guess the biggest advantage of rocks is that you can’t kill them. When hail pummels the leaves, when a sudden cold snap drops even the hardiest of shrubs, when rabbits mow down the newly planted petunias, the rocks continue to look the same, season after season… or do they?

Would you believe that last winter, some of my rocks died?


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