Q. Can you use lava rock
as a groundcover around any shrubs? I am thinking particularly of Japanese
boxwood.
as a groundcover around any shrubs? I am thinking particularly of Japanese
boxwood.
A. Lava rock was used
extensively in Las Vegas landscapes as a surface covering before desert
landscaping became popular. Desert landscaping uses specialty rock mulch of
different colors and sizes and its use has pushed lava rock out of this niche.
Lava rock has some interesting qualities, different from the rock we have
available to us today. It can be a good alternative to rock mulch we have
available to us today.
extensively in Las Vegas landscapes as a surface covering before desert
landscaping became popular. Desert landscaping uses specialty rock mulch of
different colors and sizes and its use has pushed lava rock out of this niche.
Lava rock has some interesting qualities, different from the rock we have
available to us today. It can be a good alternative to rock mulch we have
available to us today.
Lava rock, or any rock mulch for that matter, would not
be a good choice around Japanese boxwood. Japanese boxwood grows better in
soils amended with compost and the soil covered in organic wood mulch, not rock
mulch or lava rock.
be a good choice around Japanese boxwood. Japanese boxwood grows better in
soils amended with compost and the soil covered in organic wood mulch, not rock
mulch or lava rock.
Using rock mulch or not depends on the plants. I am
frequently asked which plants can tolerate rock mulch and which ones cannot.
That’s difficult to explain unless you know where the plant originated. Plants
that originate from desert climates can generally handle rock mulch better than
those which don’t. Sometimes that information is difficult to find.
frequently asked which plants can tolerate rock mulch and which ones cannot.
That’s difficult to explain unless you know where the plant originated. Plants
that originate from desert climates can generally handle rock mulch better than
those which don’t. Sometimes that information is difficult to find.
Boxwoods come from non-desert environments. They don’t
come from the “deserts of Japan”. They come from wetter and cooler climates than
ours. This suggests to avoid placing them in West and South exposures, but amend
the soil at the time of planting with compost and cover the soil with something
that decays such as wood chip mulch, which adds organics back to the soil.
come from the “deserts of Japan”. They come from wetter and cooler climates than
ours. This suggests to avoid placing them in West and South exposures, but amend
the soil at the time of planting with compost and cover the soil with something
that decays such as wood chip mulch, which adds organics back to the soil.
Lava rock falls into the category of a rock mulch. It
does break down over time adding minerals to the soil but adds no “organics”. The
same problem occurs with other rock mulches. Over a few years, the compost
added during planting is gone, replaced by the minerals without organics. These
soils may be rich in minerals but lack the physical properties needed for good
drainage, root growth and the chemistry required for nondesert plants to
thrive.
does break down over time adding minerals to the soil but adds no “organics”. The
same problem occurs with other rock mulches. Over a few years, the compost
added during planting is gone, replaced by the minerals without organics. These
soils may be rich in minerals but lack the physical properties needed for good
drainage, root growth and the chemistry required for nondesert plants to
thrive.