The uses of gravel in American gardens typically conjure up images of drainage swales, the fringes on the sides of the road and a cheap alternative to an asphalt driveway.
A long trend in European gardens uses gravel in a much more decorative style. Terraces, pathways and patios all use loose rock, mostly because it was an inexpensive, readily available surface.
Then there are the true gravel gardens. Gardens designed to be mulched completely in gravel. The texture of the rock plays well in Asian- and Mediterranean-influenced designs.
The look is not necessarily right for every bed in the landscape, but can create a special look when used with sedums, dwarf conifers and other water-wise plants.
A fully mulched area of gravel, planted with water-wise plants is the classic “gravel garden.”
These gardens are placed in areas that need little maintenance and have low water needs.
Beth Chatto, a British garden designer, has popularized the term “gravel garden” with her public display garden (www.bethchatto.co.uk).
In a miserable corner of her garden, a former parking area was magically transformed into a garden of drought-tolerant plants, mulched in gravel and reliant on only rainfall.
Gravel gardens allow a wide range of tough ornamental plants to be grown. Plants are placed so that gravel can be raked up to their crowns without covering them, creating mulch that provides a well-drained surface against the undersides of dry-loving plants.
Mulch with at least 3 inches of gravel. Any less and soil will show through and look more a mess than mulch. A good-sized rock for mulch is -inch, with clean-rounded edges. A side benefit of gravel is that typically slugs won’t cross gravel, and cats will not use a gravel-mulched flower bed as a litter box.
The plantings in a gravel garden rely on the bone structure of drought-tolerant evergreens and tough shrubs and perennials such as lavender, rock rose (Cistus sp.) and rosemary.
Bulbs create a wash of color in the spring from alliums to species tulips, and the sharp drainage gravel keeps bulbs from rotting in heavy soil and wet winters.
Drought-resistant ornamental grasses play throughout the year, from fresh new growth in spring to rich seed heads in the fall. Plants can be spaced loosely so that gravel shows through and becomes an accent.
Gravel isn’t just one specific type of rock – it describes a material that comes in different sizes and shapes.
Gravel can be crushed, chipped, tumbled or rounded and is generally considered 1/8 of an inch to 11/2 inches in size.
Choose the type of gravel for the purpose it’s needed for:
Crushed: Better for areas with foot traffic because it doesn’t roll underfoot.
Rounded rock: Has a more finished look that does well for mulching planting areas.
Choose the rock for color aesthetic and design use, or to create micro climates. White rock as mulch around the base of lavender plants stops the typical wet winter browning that happens where the plant stays wet against soil.
To calculate how much rock you need, 1 cubic yard of gravel will cover about 300 square feet 1 inch deep. Total the number of square feet to cover, divide by 300, and multiply by the desired depth in inches. This will give the number of cubic yards you’ll need.
Gravel eventually starts to sink into the soil and may need to be replenished. Typically in older gardens, the base will start to thin out in heavy traffic areas.
To keep the surface tidy, a loose fan rake will remove leaves and level gravel. A tamping of the gravel surface occasionally will also help keep levels firm.
A leaf blower works for dried leaves and debris when the blower is directed to skim the surface. Weeding is most intensive in the first few years of establishment while the plants are filling in.
Never let weeds get away from you and creep into the gravel mulch or they will become harder to pull.
After a few years of weed-pulling diligence, it will just be a matter of removing self-seeded ornamentals and the few weeds that blow in.
Try these drought-tolerant plants for your gravel garden:
SHRUBS & EVERGREEN PERENNIALS
California lilac (Ceanothus sp.)
Rock rose (Cistus sp.)
Sage (Salvia sp.)
Evening primrose (Oenothera)
Globe thistle (Echinops)
Ice plant (Delosperma cooperi)
Sea holly (Eryngium)
Sea kale (Crambe maritima)
Blue oat grass (Helictotrichon s.)
Mexican feather grass (Nassella tenuissima)