Xeriscaping with Rock Gardens

A history of rock gardens and their plants offers ideas for all home gardens.

Hymenoxys acaulis
Item # 59001 		Hymenoxys acaulis
Sundancer Daisy

each $5.99
3 to 6 plants $5.79
7 or more $5.59
Origanum libanoticum
Item # 73050 		Origanum libanoticum
Cascading Ornamental Oregano

each $7.99
3 to 6 plants $7.79
7 or more $7.59
Achillea serbica
Item # 10070 		Achillea serbica
Serbian Yarrow

each $7.99
3 to 6 plants $7.79
7 or more $7.59
Salvia daghestanica
Item # 84713 		Salvia daghestanica
Dwarf Silver-Leaf Sage

each $5.49
3 to 6 plants $5.29
7 or more $4.99
Anacyclus depressus
Item # 17210 		Anacyclus depressus
Mt. Atlas Mat Daisy

each $7.99
3 to 6 plants $7.79
7 or more $7.59
Echinocereus triglochidiatus
Item # 46980 		Echinocereus triglochidiatus
Claret Cup Hedgehog

each $5.99
3 to 6 plants $5.79
7 or more $5.59
Delosperma Sampler
Item # C0041 		Delosperma Sampler

Sampler $121.76
Rock Garden Design & Construction
Item # 99678 		Rock Garden Design & Construction

each $29.95
Rock Garden Plants
Item # 99679 		Rock Garden Plants: A Color Encyclopedia

each $59.95

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History

Around the 11th century, Zen priests began experimenting with rock gardens in China and Japan; however, their emphasis was on unusual rock forms rather than on plants. Seven hundred years later, when an upsurge in plant exploration began, rock gardens in Europe and in America began taking a different form. During the mid-1800s, travelers inspired by alpine elevations tried growing miniature alpine displays in their own gardens.

Today

Countless rock gardens still replicate higher elevation ecosystems but many also contain plants from more temperate and even desert climates. But the element that’s shared by all rock gardens is the diminutive stature of most of the plants-and stones, of course.

A few lucky gardeners have natural rock outcroppings on their properties, which can become the foundation for rock gardens. For most of us, it’s necessary to create a rock formation, but making it look natural is the tricky part. When you’re just starting out, visit rock gardens and read books about rock gardening. The best ideas, though, come from examining natural outcroppings in your own geographical area.

While scouting around, also take note of plants that already exist in the formations, including any deciduous trees, conifers or shrubs. Observe how they grow naturally in rocky crevices. If you’re using natural rocky areas on your own property, determine what plants can be kept then supplement with small plants that can be tucked into crevices and planted in adjacent pockets of soil. You’ll have a rock garden in short order. Many helpful hints on stone placement and other aspects of rock gardening can be found on the North American Rock Gardening Society web page at www.nargs.org.

Constructing a Rock Garden

You’ll probably need to move or bring in soil to create some contours. When rock placement starts, the hardest thing to do is to bury at least a third to half of each stone. Since they either cost a lot or were hard to gather, the first inclination is to let all of the stone show. However, if you do this rocky area may not appear natural.

Rocks

Rocks need to be securely situated to allow you to step on the larger ones without having them shift or pop out of the soil. Be sure not to mix many different types of rocks. A hodgepodge of rocks looks very unnatural and distracts the eye.

Specimen rocks can be featured here and there, but should not overwhelm the design.

Soil

Good soil is the key to a successful rock garden. As a general rule of thumb, the wetter your climate the faster draining the soil mix should be. In arid climates we recommend a blended mix of 4 parts clay, clay loam or loam, 1 part high quality compost, 3 parts course sand and or crushed gravel, and 2-4 lbs of Yum Yum Mix per cu. yd. of soil.

Add more sand and gravel and less soil in wetter climates. Check with the NARGS website for their recommendations on rock garden soil mixes.

Plants

Now we’re ready for the fun part – selecting the plants. Pleasing aesthetics and landscape design principles really come into play with the rock garden.

Most of the plants used in your rock garden should be fairly small. Remember all the work you did creating the rock formation. You don’t want to have it totally obscured with a dense jungle of plants.

Plants typically don’t crop up as single specimens. Individual varieties usually occur in drifts or will be found scattered about in close proximity based on how they propagate. Seeds fall down so a drift may be found going down the slope.

Tallish Plants

There should be some variations in plant height. Some of the smaller varieties of Penstemons are good choices for the vertical element. The flower spikes add some height while the mat forming foliage fits nicely among rock crevices. Penstemon linaroides v. coloradoensis (Colorado Narrowleaf Beardtongue) with its lavender flowers is a superb specimen for the rock garden. Its intensely blue evergreen foliage is an added benefit for winter interest.

Penstemon viren (Blue Mist Beardtongue), with its dainty lavender and blue flower spikes, is another variety that fits nicely in the rock garden when planted in drifts. Several varieties of Penstemon pinifolius (Pineleaf Beardtongue) are good candidates. They typically have reddish orange blooms but some varieties are yellow to mango colored. As they mature they form into small evergreen shrublets.

Low-growing plants

Penstemon procumbens ‘Claude Barr’ (Mat Penstemon) which is diminutive- one inch in height-but covered with small deep blue flowers in early spring.

A touch of white can be incorporated with Achillea serbica (Serbian Yarrow), a rugged plant with gray mats of narrow evergreen leaves.

Anacyclus depressus (Mt. Atlas Daisy) originates in the mountains of the Mediterranean. Its white flowers have a red underside that is visible in the early mornings before the blossoms unfold.

Origanum libanoticum (Cascading Ornamental Oregano) with its green hop-like bracks and protruding pink flowers is ideal for a rocky perch where the trailing flower stems show to best advantage.

Texture and Color

A combination of foliage color, including blues, grays and greens adds a lot of interest to a garden and plants that have evergreen leaves are a special bonus.

Select plants that have a variety of delicate foliage but use some with bolder, more definitive shape to the leaves.

Plan some large drifts of a single color so the garden does not appear to have polka dots.

Sunny and hot areas

Consider using cold-hardy cacti and succulents mixed with other heat-loving herbaceous perennials. The effect can be most stunning. Some suggestions are:

Hymenoxys acaulis (Sundancer Daisy) is a summer-long bloomer that makes a wonderful centerpiece.

A good companion cactus is Echinocereus. And the quintessential rock garden plant is Delosperma (Iceplant) which blooms profusely for most of the summer and loves to spread in-between and over the rocks.

Rock gardening has evolved from a practice where hard-to-grow mountain specimens were placed into created stone pockets in a far off garden. Nowadays, rock gardens can be artistically arranged around stone formations with plants that have never seen a mountain slope. And often they are the center attraction. The main goal for any rock garden is to have a delightful combination of stone and plants that is a delight for the eye.