Does your yard have a hard-to-mow slope? Or, if you have a postage-stamp lawn, have you wondered about eliminating that tiny patch of grass? Or, would you just like to add a fun landscape feature that would be a conversation piece?
There's a single solution to each of these questions, and the solution is mostly maintenance-free, time- and budget-friendly: create a rock garden.
"Rock gardening is a style of gardening inspired by what you might see on the top of a mountain where you have a silty rocky landscape and very distinctive small and compact plants," says Joseph Tychonievich, a lifelong gardener and plant lover whom Organic Gardening magazine recently named one of "six young horticulturists who are helping to shape how America gardens." "When you translate that into a garden, you are growing rock garden style plants, which are usually very small and compact with often really beautiful floral displays, and combining them with a well-draining soil and often stones or rocks to complement the beauty of the plants," says Tychonievich.
Rock gardens are great for many situations, emphasizes Tychonievich, whose book "Rock Gardening: Reimagining a Classic Style" is on publisher Timber Press's best-seller list. "One of the great things, especially for the millennial generation or young homeowners, is that rock gardens work well in small spaces." He defines small spaces as a little yard, a patio or an apartment balcony. "They are also great if you have a steep hilly landscape where it would be difficult to grow typical garden plants. That's a natural area for a rock garden because rock garden plants do great on those hilly conditions in stony lean soils." You can also do a rock garden on flat surfaces or in shade and, in what might be a surprise for some, rock gardens are better suited for an herb garden than rich garden soil," Tychonievich says.
Rock gardens are also environmentally friendly. "With stones and a gravel mulch you can make a very beautiful landscape that you are not going to have to mow and that would be very water-wise," adds Tychonievich. Anyone planning to put in a rock garden should remember that rock garden plants, which come in a variety of shapes and textures and often produce brilliantly colored flowers, thrive in dry conditions. That's why they don’t need the irrigation and heavy fertilizer applications that a lawn or mixed ornamental flower border would require.
Rock garden basics
The size rocks you would use in a rock garden depend on the scale of the garden you're creating and your budget. "I've seen a container rock garden that was made from just a few stones found in a parking lot," says Tychonievich. "If you're doing a big installation, you may need to purchase them." However, he adds, "You don't need a ton of stones and you can even do a rock garden without big rocks. Depending on your budget, you can decide on how much you want to invest or what kinds rocks and stones you can find."
Whatever look you create, the most important thing to remember is to create drainage for the plants. This will occur naturally on a slope, but on a flat area you will need to create a raised bed. "Normally when we create a garden we are thinking of adding lots of compost to make the soil very rich and moisture retentive," Tychonievich says. "For rock garden soil, you usually add sand or gravel to the soil mix to allow the water to drain away."
A typical soil mix for sunny rock gardens is between 1/3 to 1/2 native soil and the rest a mix of sand and gravel, Tychonievich says. "If your native soil is naturally sandy, you could use more native soil. if it is a heavy clay, you'd want to use less." Another option, he points out, is to simply put a layer of pure sand and gravel — 3 or 4 inches at least — over your native soil. That would allow the rock garden plants to send their roots down to the wetter native soil below, but would prevent their crowns from sitting in wet conditions. Shade rock gardens don't need to be as well drained. For them, Tychonievich advises using native soil amended with compost or leaf mold unless the soil is a very wet clay.
If you're not familiar with rock garden plants, here are Tychonievich's top five choices for sun and shade rock gardens and his descriptions of each plant.
1. Sunny rock gardens
Hens and chicks (sempervivum). A classic rock garden plant. They are very diverse, beautiful and collectible, though not particularly rare, and you get lots of them. They are a good starter plant because they are practically un-killable. Kids love them. One of my favorites.
Iris reticulata hybrids. These are actually bulbs. You can grow them in typical garden soil, but they tend to not do well there and dwindle away after a few years. In the well-drained conditions of a rock garden, they really thrive, bulk up and provide a really great hit of color early in the season.
Arenaria. There are a bunch of different species. They make a very distinct sort of mat of foliage only a few inches tall that creates a very beautiful structural form in the garden. They become really cool plants as they mature.
Zinnia grandiflora. This is a species native to the Western U.S. that is winter hardy to Zone 5. It’s only 3 to 4 inches tall and spreads out to form a mat maybe a foot across. The plants produce lots of blooms of yellow zinnia-type flowers but on a small scale. It’s very carefree and easy to grow, blooms all summer and will come back every year.
Delospermas (ice plant). This is a great, hardy mat-forming succulent just a couple of inches tall that produces really beautiful flowers. There are a lot of great selections right now. Firespinner has beautiful magenta and orange flowers. This is one of those plants that if they don’t have good drainage they tend to rot out and die. But if you give them a well-drained sandy-gravel soil in the rock garden they will respond with succulent foliage and a beautiful floral display throughout the season.
2. Shady rock gardens
Miniature hostas. These are just as easy to grow as large hostas, but they look really great combined with rocks in a rock garden. They appreciate a little more drainage than the large hostas.
Ramonda. This is a genus of plants related to African violets. The flowers look very similar to African violets, but are winter-hardy perennials that bloom in the spring. They don’t like direct sun, so they are a good choice for a shade rock garden. They are also fun plants to grow because they are a resurrection plant. If they get dry, they curl up into a little ball and look like they are dead. But, as soon as they get water they open right back up again into their full leaves. This characteristic makes them a fun thing to grow, especially for kids. They aren't that common and can't take direct sun. In the right, conditions they are easy to grow.
Cyclamen hederifolium. This hardy little bulb is called the ivy leaf cyclamen. It looks like the tender florist cyclamen but is a very hardy perennial. It is in active growth in the fall, winter and spring and goes dormant in the summer. If you combine it with plants like hostas, it will be dormant when other perennials are growing in the summer and when those plants go dormant it will come up and flower. So, it’s a nice contrast for winter interest and color in the shade rock garden. The foliage comes in different sizes and shapes and with spectacular mottling. Beautiful pink or white flowers appear in the fall or winter.
Saxifrages. This is one of the classic groups of rock garden plants for shade. It is a diverse and wonderful group of plants that feature weird rosettes of silvery gray foliage. Most don’t do well in the Deep South. One section that does, though, is the mossy group. The interesting foliage is evergreen and, like all saxifrages, the plants produce attractive flowers.
Alpine columbine. Can do sun or shade. Regular columbines are really large, but there are some nice small ones, like Aquilegia scopulorum, that look like a regular columbine shrunk down to maybe four or five inches tall. These beautiful and cute little perennials are native to the Rocky Mountains.
3. Container rock gardens
If you live in an apartment or condo where your only gardening space is a balcony, you can still have a rock garden by creating one in a container. These are called rock garden troughs and are a popular way to do rock gardens, says Tychonievich.
"Because the plants are so small and compact, putting them in a container is a really beautiful way to display them," he continues. "You can fit a lot of interesting and different plants into a really small area. This gives them a fun and interesting look."
Container rock gardening is not only for people who lack an outdoor growing area. "A lot of rock gardeners put some of their most special and favorite plants in containers so they can really enjoy and display them," Tychonievich says.
4. Edible rock gardens
One of the things that Tychonievich says younger people always ask him is if they can grow food in rock gardens. His answer is a resounding yes.
"You can't grow many vegetables in a rock garden, but lots of herbs will thrive there," he says. "Thyme, sage and rosemary are plants that are well suited to rock garden type conditions. They will actually be hardier, live longer and have stronger flavor in a rock garden because in drier conditions they will produce more of the oils that give them flavor."
Intermixing herbs them with other plants is a fun way to make a rock garden both ornamental and edible at the same time, he says. Other herbs that also work well in a rock garden include oregano and lavenders. Tychonievich recommends the lavender variety "Lady" because it tends to stay smaller than most lavenders, which can get too large for a rock garden, and creeping varieties of rosemary.
5. Year-round look
Finally, Tychonievich says not to be misled that thinking a rock garden will look cold and drab in the winter.
Beauty is where you find it and, while he finds the stones themselves to be beautiful in winter, he says there’s a way to give a rock garden an extra appealing cold-season look. "There’s a lot miniature conifers and evergreens that do great for winter interest, and then a lot of the early spring or late winter blooming bulbs like the blooming irises thrive in rock garden conditions."
All photos taken from "Rock Gardening: Reimagining a Classic Style" © Copyright 2016 by Joseph Tychonievich. All rights reserved. Published by Timber Press, Portland, Oregon. Used by permission of the publisher.