Between a Rock and a Hard Place

Left to their own devices, plants seek out just the right place to set down roots. Sometimes the homes they find are small ones. It’s not uncommon to see plants growing from cracks in pavement and stone walls or from between steppingstones.

When plants grow in crevices, they add a touch of charm to the garden, says Fullerton landscape architect and contractor Kathryn Rue of the Group Inc.

“Planting in crevices softens the hardscape and gives the garden a more natural appearance. Sometimes it even creates a magical effect.”

Planting in crevices also hides flaws, such as unsightly cracks, and offers more variety, says Rue, who specializes in residential garden renovations. She often tucks crevice plantings into a landscape design.

“The great thing about crevice plants is that you don’t need to do a lot of them to make a statement,” she says. “I recently planted a pansy in a crevice at the base of a pathway light, and the plant really set off the light.”

Crevice plants give hardscape a much more interesting look, agrees Norm Yoder, who co-owns Friday House Gardens, at Country Roads Antiques in the Orange Plaza: “Planting in crevices gives an otherwise boring hardscape area a natural, abandoned look that can be very appealing.”

Squeezing In Variety

Weeds grow in cracks naturally, but a gardener need not be at the whim of nature. It is possible to replace weeds with small, desirable plants. You can also seed plants such as alyssum, viola, lobelia, chamomile and California poppy in crevices. If you’re lucky, they’ll re-seed themselves.

Drought-tolerant plants tend to thrive in cracks and crevices. Many are native to California or other fairly dry Mediterranean climates. Alpine-type plants native to high elevations also make good crevice plants--that’s how such plants grow naturally.

Plants suited for rock gardens, such as erodiums, also do well in crevices, says Robin Parer, owner of Geraniaceae Nursery, a mail-order company in Kentfield, Calif., that carries a large variety of erodiums.

Like weeds, many plants that thrive in cracks, once established, do well with little care, Yoder says: “They tend to be shallow-rooted and don’t need a lot of root space.”

Some crevice plants will even stand up to light foot traffic and can serve as living carpets--or perhaps throw rugs.

“Although there are no plants that can take heavy foot traffic, there are a few--like creeping thyme, pennyroyal, Corsican mint, baby’s tears and Campanula porschyana--that can be planted in an area such as between steppingstones,” says Yoder, who creates garden paths by setting down bricks and filling the grout lines with soil and plants.

“When you walk on the steppingstones and brush or step on aromatic plants like thyme and pennyroyal, it releases a scent,” he says.

If you don’t have many cracks in your landscape, or your cracks are too small, there’s a solution, says Rue, who has created crevices in the yards of clients. She suggests selectively cutting out spaces in concrete by hitting the area with a rotahammer, a small jackhammer. If the concrete is a little broken, you may be able to break it further with a hammer and chisel.

With brickwork or stonework, it’s usually best to remove entire pieces or plant in between, rather than in cracks.

To plant in a wall, use existing crevices or get professional advice from a landscape contractor before creating larger spaces.

Tips to Grow On

In crevice planting, seeding is preferable when possible, because it allows a plant to develop its own roots. Many plants that do well in crevices don’t come in seed form, though, so keep these tips in mind:

* Inspect the area before planting to determine root room. Rue suggests inserting chopsticks into the crack to see how far they will go. It’s important to water the area and watch how well it drains.

* If drainage is poor, excavate the site and replace as much soil as possible with planter mix or azalea mix, depending on what you’re planting. The soil should be heavy enough to hold moisture and not wash away, but not so heavy that no water will penetrate.

* Choose the smallest plants possible. Four-inch plants generally are too large for crevices. Look for pony-packs, color-packs or 2-inch pots.

* When planting, make sure that the roots have good contact with soil and be as careful as possible to minimize root damage.

* If planting during the summer, protect the plants from sun for three or four days while the roots start to assimilate. A vitamin B1 application may be helpful against root shock, as is applying a plant anti-transpirant before planting. That product, found in nurseries, prevents plants from losing water through their leaves.

* Expect some dieback after planting small seedlings. Some crevices in concrete and stone may be too warm for plant roots. Although dieback is disappointing at first, take heart. The plants will adapt and come back stronger for it. In the long run, the plants will have adjusted to the small space.

For information on erodiums, contact Geraniaceae Nursery at (415) 461-4168 or on the Internet at https://www.freeyellow.com/members/geraniaceae or e-mail at geraniacpacbell.net. A catalog is $4.

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Plant Possibilities

A surprisingly wide variety of small plants thrive in crevices. Following is an alphabetical sampling of plants that can be tucked into small spaces and will add depth and dimension to a garden. They were suggested by Fullerton landscape architect Kathryn Rue and Friday House Gardens co-owner Norm Yoder:

Alyssum

Baby’s tears

Basket-of-Gold (Aurinia saxatilis)

Blue fescue

Blue star creeper (Laurentia fluviatilis)

California poppy

Campanula poscharskyana

Carpet bugle (Ajuga pyramidalis ‘Metallica Crispa’)

Chamomile

Coconut thyme (Thymus pulegioides ‘Coccineus’)

Corsican mint

Creeping thyme (Thymus praecox arcticus, T. serpyllum, T. drucei)

Dichondra

Dwarf pennyroyal

Elfin thyme (Thymus serpyllum ‘Elfin’)

Erodium (Erodium cheilanthifolium/E. chrysanthum)

Hen and chickens (Sempervivum tectorum)

Herniaria glabra

Ice plant

Irish/Scotch moss (Sagina subulata)

Lavender thyme (Thymus thracicus)

Lemon verbena

Miscanthus adiago

Mexican evening primrose

Moneywort (Lysimachia nummularia)

Moss pink (Phlox subulata)

Nicotiana

Oxalis

Pink Chintz thyme (Thymus serpyllum ‘Pink Chintz’)

Santa Barbara daisy

Sea thrift (Armeria juniperifolia)

Snow-in-summer (Cerastium tomentosum)

Speedwell (Veronica repens)

Stonecrop (Sedum)

Sunrose (Helianthemum nummularium)

Valerian

Viola (V. odorata, V. sororia, V. priceana)