Succulent plants live by their own rules. To really understand their preferences, I had to throw out what I know about traditional gardening. Now that these plants are finding their way to every corner of America, those who have fallen in love with their beauty and easy care will have to rethink the rules as well.
If you study cactus and succulents in the wild, as I do here in the California desert, observation reveals many things. These plants tend to occur on well-drained rocky, south-facing slopes. They perch in nooks and crannies where there is little to no soil. The roots survive in crevices that reach deep into the cliff where rock has trapped moisture year-round.
Walk through the desert and you’ll find plants springing out from beneath rocks and boulders. Here the ground is sandy gravel and porous, so the plants send their roots beneath the rock where it’s cool and moist. Sure, they root out into the open to catch scant rainfall, but rain moves so quickly through the ground that it’s difficult to capture. The rain will soak the ground beneath the rocks where it remains long after skies have cleared, so roots have more time to take it up.
Soil beneath rocks is also more stable. In the desert, sudden rainfall causes enormous erosion, carrying sand far and wide. Plants that depend on this soil for stability will be washed out unless they find anchorage beneath a rock or boulder.
The natural model is also why I like to use at least one decorative stone when I plant young succulents in pots. It’s hard to apply water without its velocity picking up particles as it hits the potting soil. This causes the soil levels to drop on the watered side and the traveling particles build up on the other side.
Soil movement is more prevalent in pots containing very young succulents and cacti. I find a beautifully complementary “watering” rock to go into the pot. When I water, I pour it onto the rock, and from there the water flows naturally into the surrounding soil. There is no high-velocity flow, so there is no erosion, and I can be sure there is plenty of moisture beneath the stone.
Watering inevitably brings the white perlite and woody matter in the potting soil to the surface, where it floats. This is reduced by using a fine gravel mulch layer on top, which mimics the layers of soil laid down in the desert from rain events. When you water your rock, it flows down into the gravel so the root zone remains undisturbed.
You might be surprised to discover your succulents tend to send out pups on the far side of the stone. Over time, many succulents flesh out the ground around the stone to create a truly eye-catching adult.
Ever since I began using watering rocks, I’ve become a rock hound, collecting colors, shapes and sizes that work with my plants. Every hike, trip to the beach or visit to my favorite stone yard yields great finds. Don’t overlook specialty minerals that can turn a $2 succulent into a big-bucks specimen in just the right pot.