Rock Garden Design Ideas Guide

How to plan a rock garden

Rock gardens fit extremely well into water-wise landscapes, compliment paver patio and driveway installations, and also serve as stunning focal points. However, if the goal is for a rock garden to look like a natural landscape, it must be well-designed.

While these special gardens require extra thought and planning, rock gardening is considered a bit more satisfying. Gardeners are able to become more intimately acquainted with each plant because they’re usually smaller and more spaced out than in other garden types. Rock gardens are also fantastic solutions for sloped yards and small, unusually-shaped areas where mowing a lawn would be too difficult. With this in mind, here are things to keep in mind when planning a rock garden.

Rock Garden Designs

Rock Garden

Some homeowners opt for rock gardening because their home’s existing landscape space requires it. Others, create rock garden designs based on personal preference.

It’s a good idea to take a look at rock gardens that are about the same size as yours in order to get a feel for scale, types and quantities of rocks and how rocks and plants are placed.

On the West Coast, these are the most common rock garden designs:

  • Alpine rock gardens: These should look like windswept landscapes you’d find on a mountain. You’ll see rugged boulders with flowering plants in between and maybe a sparse tree or two that also looks a little battered by the wind. Typical alpine plants won’t thrive in coastal Southern California, but there are plenty of suitable alternatives.
  • Desert rock gardens: Think of your last drive through the desert where there probably were succulents, cacti, little to no ground cover and maybe some wildflowers sprinkled throughout.
  • Woodlands rock gardens: These rock gardens are found under big trees and populated with plants that thrive in shade.
  • Japanese zen rock gardens: Minimalist in look, Japanese zen gardens tend to use rock focal points, gravel and a few plants sprinkled in. The intent is to use these gardens as places of meditation and quiet reflection.
  • Anything goes rock gardens: Many gardeners these days opt simply for natural-looking rock formations and plug crevices and empty spaces with a mixture of succulents and other small plants they simply find pretty.

The type you choose largely depends on the location but all need good drainage. Desert rock gardens are perfect for flat spaces, woodlands obviously thrive under large trees while alpine rock gardens are great options for slopes. If your heart is set on an alpine style, by all means think about how you can turn a flat space into a small mound.

Rock Placement Matters

Rock Garden

The largest rocks should be placed first and buried about 1/3 beneath the ground in order to look natural. Another way to mimic a rock garden you might see in nature is to keep the types of rock used to one or two. Incorporating rocks of varying shapes and sizes will look inherently messy, new and unlike anything one might see in the wild.

See if you can make the rocks peek up from the ground in a formation that makes one assume the garden is the tip of an underground rock formation. A good rule of thumb for larger rocks is to make them look like they’re connected underground, with crevices separated by dirt, gravel or plants.

Rocks that are porous will achieve a weathered look (as if they’ve been in place for a while… desired for rock gardens) faster than rocks with smooth surfaces will because water, moss and lichens can’t penetrate.

Be sure to allow for gaps in soil that are wide and deep enough for plants to grow. Small succulents have tiny root systems so can fit into some troubled spots provided drainage and sunlight are good.

Check the Soil Before Buying Plants

Dry Garden, Palos Verdes

If your area already has rocks in place, it may be wise to test the soil to see which plants will grow well in its pH level. Otherwise, if your plants of choice need a different pH, you may need to rake out the existing soil and replace with another or work to change the soil’s pH before planting.

The easiest thing to do is base plant selection on soil and sun conditions. Top the soil with a mulch to prevent weeds and water run-off especially in sloped rock gardens.

Best Plants for Rock Gardens

Del Mar Heights - Let Color Bring Life To Your Home

When considering plants for a rock garden, again, pay attention to scale. Small rock gardens require compact plants and dwarf trees. And while it’s ideal to have plants that will cascade over the rocks, you don’t want them so big they hide rocks either. Good rock garden plants should also be drought-resistant.

If landscaping an existing rock garden, observe its drainage. Areas, where moisture tends to pool, can handle plants with higher water needs, a technique used in xeriscaping.

Gingko House, Harrison, NY

If leaning toward an alpine garden, be sure to place plants right next to the rocks. This is how they grow in the wild in order to take advantage of rain water that drips off of the rocks.

Small plants like sedums and echeverias (both succulents) can happily grow even in the smallest of crevices. Blooming ice plants make good ground covers for rock gardens as does sea pink armeria with its little pink flowers. Woolly thyme is a creeper and another good option (albeit a slow-grower) for a cascading effect.

Medium plants can include aeoniums and euphorbias as well as pretty coneflower plants and lavenders.

Large plants open up a wide variety of native plants like buckwheats and sages.

When it comes to trees, look at dwarf conifers and Japanese maples. For seasonal color, consider adding bulbs like daffodils, iris, crocus, and alliums.

Rock Container Gardens

Some of the same principles apply to rock gardens in containers, another popular way to add interest to an outdoor living space. They look particularly great in rock troughs.

Your Turn…

Do you have a rock garden in your backyard?