How to Design a Rock Garden: Landscaping With Rocks and Boulders
Plants and Rocks Are a Natural Combination
When the landscape gives you boulders and stones, create a garden that rocks!
Our property was sculpted by the Ice Age: The retreating glaciers left sheer granite outcroppings with huge chunks of exposed ledge, and the surrounding woodlands are dotted with rocks and boulders of all shapes and sizes.
While many gardeners view rocks and stones as obstacles—heavy rocks are hard to move and hard on tools, and the big boulders just won't budge—we looked for ways to integrate the rocky terrain into our landscape design with several different types of rock gardens, including dry and sunny, shade, woodland and even water gardens. The lead photo shows just one example: this little rock garden was built at the base of a granite ledge and creates a transition between the woodlands and the lawn.
Though most rock gardens feature combinations of smaller plants and hardy succulents packed in a rocky setting, there are many different sizes, varieties and styles of rock gardens. Some utilize the natural slopes and surroundings as the basis for rock gardens, either to tame the hillside grade, control water runoff or to convert an eyesore into an attractive planting. Other gardeners create berms and haul in rocks to create interesting spots for plants to grow.
How to Design a Rock Garden
We've got lots of rocks: Many of the larger boulders and the exposed ledge in our landscape are incorporated into the design of the planting beds and garden paths since it is as easier to plant around the rocky obstacles than it is to move them out of the way. Digging holes for plants and building outdoor projects uncovered even more buried rocks and stones, and we often need to use a crowbar to lever the larger rocks out of the planting holes. Or if the rock is too large to move, we are forced to move the planting hole to a slightly different spot.
Nearly every rock and stone finds a new home with a purpose in the landscape: the largest stones become focal points in the planting beds. Mid-sized rocks are stacked into low retaining walls against the hillside or placed as edging to define the borders of paths and planting beds. The smallest rocks and stones are used for filling the gaps, and for "chinking" behind the larger rocks to hold them securely in place. Flat rocks are prized as capstones for stonewalls and as stepping-stones. We've even carried interesting shaped rocks that we found in the woods into the rock gardens to add to the visual appeal and continue the rocky theme of our backyard landscape.
Our small garden pond in this photo is another example of working with (and around) the rocks in the landscape: the granite outcroppings form a natural crevice for a small stream and waterfall that cascades into the pond below. Digging the pond under and around the boulders was a challenge, but the results are worth the effort.
How to Build a Rock Garden
When creating a rock garden, selecting the proper location is one of the primary factors in determining the size of the planting bed and the types of plants that will thrive in the micro-environment. This evergreen rock garden is another transition element between the lawn area and the woodland gardens in the background. The garden bed is sited just beyond our decks and because it is part of the primary view of our backyard, the rock garden is designed to provide visual interest all year round.
The colors and textures of the conifers contrast with the lichen-covered rocks, creating an attractive combination. We hauled a few rocks from the woods and placed them strategically in the bed to highlight the plantings and to visually separate the large bed into smaller areas for greater impact. A border of rocks completes the bed.
Rock Garden Hostas
Just beyond the Evergreen Rock Garden is one of our Woodland Rock, featuring a combination of hosta plantings tucked in the crevices between several large boulders and ledge outcroppings.
This shady rock garden weaves a tapestry of colors and textures between the natural rock sculptures and the softer foliage of the plant materials. A pea stone path with slate stepping-stones reinforces the rock garden theme.
Staging Rocks in the Landscape
Combining the plants and rocks helps to anchor them visually in place. We carefully select the size and shape of the rocks, using a combination of upright rocks, rounded rocks and rocks with hard edges to create pictures that change throughout the year with the different seasons.
The rock placement attempts to mimic nature, with the rocks and plantings scattered in random groupings, yet each is carefully positioned (and often moved several times) to create a natural appearance.
A rock sitting on top of the ground looks out of place. To further anchor the rocks visually into the garden, bury portions of the rock down into the soil. Burying a portion of the rock into the ground not only stabilizes it, but you can also control the exact positioning of the stone. In some case, we bury 1/3 to 1/2 of the rock into the ground.
Stack Them Up!
Stacking rocks into a low stone wall creates more planting options. Cut into the slope, these layered stones are simply dry-stack on top of each other to create a low retaining wall and terrace as a backdrop for these hostas. Dry-stacking means that no mortar is used to secure the stones in place.
We selected several flat and rectangular shaped stones for this wall. The first layer of stones are dug into the soil and leveled to provide a secure foundation. The next layers of stone are arranged on top of the first layer and positioned so each stone spans the gap between the rocks directly below. Similar to building a brick wall, this makes for a stronger and more stable stone wall. And it makes for a great backdrop for the hosta, lily-of-the-valley and the little toad house.
A Destination in the Garden
The meandering paths offer different views of the rocks and plantings as you wander through our woodland gardens. It's also important to provide a place to sit and relax, and this stone bench is the perfect spot. Split from a chunk of exposed ledge, this piece of stone was a lucky find. And it is very heavy—we used a small tractor to drag the stone down from the hillside.
Though our stone bench is literally as hard as rock, it is also surprisingly comfortable to sit for a spell and it fits well into the rock garden theme. It is also very low maintenance. If you are not as fortunate to have a quarry of ledge in your backyard, check with your local gardening center for either a similar piece of stone or perhaps a pre-formed stone bench.
Our Fieldstone Fire Pit
Another destination spot in our backyard is the fire pit, made from what else but fieldstone. We collected more rocks from around the property, dug a shallow pit and then layered the edges with a few rows of stacked fieldstones.
The area around the fire pit was cleared of any brush and covered with a layer of pea stone. The gravel base ties nicely into pea stone pathways leading up to the fire pit, and protects the ground from any wayward embers.
Ledge Rock Gardening
Guarded by Gargoyles
Pulling back a bit from the lead photo and to put the sheer size of the ledge rock into perspective, the photo above shows an expanded view of the same small dry and sunny rock garden.
Stacked fieldstone collected from around the property forms the beds of the rock garden, creating a transition between the wilds of the woodlands and the lawn area.
Taken in early spring, the photos do not really give justice to this little area of the dry and sunny rock garden. The gargoyle is surrounded by a low-growing cactus that is actually native to Connecticut, though it has not yet rebounded from the long, cold and snowy winter.
But the Cactus Does Bloom in the Summer!
This little cactus is right at home in our Connecticut rock garden. It must be a happy little plant, since it blooms every year in a burst of bright yellow flowers. Each bloom lasts just one day and after it fades away, a little cactus pear fruit develops. According to a botanist friend, this variety of the prickly pear cactus is actually native to Connecticut.
Do You Have A Rock Garden?
Do You Have A Rock Garden?
How to Build a Rock Garden - A short video showing the step-by-step process for building a small rock garden along with several design tips.
After Waiting for Thousands of Years, these Rocks are Spotlighted in the Garden
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2013 Anthony Altorenna