Giving In to Frond Desires

Beguiling to botanists, captivating to collectors and gratifying to gardeners, ferns are among the most popular garden plants.

These ancient plants, on earth for more than 300 million years, are prized for their foliage, technically called fronds. There are thousands of types of ferns, ranging in height from a few inches to 50 feet.

Fronds can be tough and leathery, like staghorn ferns, or delicate and wispy, like maidenhair ferns. They can be found over much of the world but are more often associated with tropical rain forests or dense woods.

“I think they’re beautiful,” said Herb Wilkinson, a fern collector and volunteer who tends the fern collection at Sherman Gardens in Corona del Mar.

He dubbed his Huntington Beach house Casa Verde because of the 100 ferns growing in containers and in a greenhouse.

Wilkinson prefers Davallia (one well-known variety is squirrel-foot fern, used as a ground cover or in hanging baskets) and Polypodium (a classification for ferns that grow by spreading rhizomes and can be used as ground covers or in hanging baskets).

Ferns are basically classified as tree, native or exotic. Tree ferns, such as Australian and New Zealand, produce large fronds on top of treelike stems. They are often found in Southern California landscapes with a tropical motif.

Ferns native to the Pacific Northwest and Northern California can also be used in local landscapes as long as they have shade, fast-draining soil with a good amount of humus and are protected from frost or hot, dry winds.

Exotic ferns from tropical parts of the world are also appreciated for their decorative use in hanging baskets, on slabs (like staghorn ferns), indoors or in greenhouses.

Barbara Joe Hoshizaki, botanist, retired college professor and author of “Fern Growers Manual” (Knopf, 1975), has traveled around the world, studying ferns in their native habitats in North and South America, the Pacific Islands, Southeast Asia, Australia, New Zealand and Africa. She collected numerous specimens, and in her garden in Los Angeles grows close to 1,000 ferns, both in the ground and in containers.

She admits to a fascination with their life cycles as well as an appreciation of their diverse foliage, green hues and overall appearance.

“As a botanist, I’m attracted to ferns because they have two separate lives,” she said. “I’m fascinated with their life cycle, their varied textures, sizes and differences in growth habits.”

Unlike most members of the plant kingdom, ferns do not produce seeds or flowers. They reproduce through spores on the fronds’ underside and they alternate generations.

“A little part of a fern’s life cycle includes the formation of a one-quarter-inch little plant, separate from the adult, and living on the underside of the frond,” she said.

For novice fern growers, Hoshizaki recommends starting with easy-to-grow Australian tree ferns.

More challenging is the effort required to grow ferns indoors. For those determined to add them to their indoor decor, she recommends Boston ferns.

“People eventually neglect them, and they go downhill,” she said. “The problems come from not providing enough humidity, especially in cooler weather when heaters are turned on.”

Like any plant, ferns thrive when their natural growing conditions are replicated in a garden or container.

“They need well-draining soil, and it’s important to amend the planting soil with organic material and sand or sponge rock,” Hoshizaki said. “It’s better to put a $1 plant in a $5 hole than vice versa.”

Ferns need moisture but not soggy conditions. They also benefit from regular fertilizing. Hoshizaki advises doing so every three weeks during spring, summer and mid-fall with a balanced liquid fertilizer or fish emulsion applied to the root zone.

Part of the fern’s life cycle includes the death of fronds. These brown, brittle reminders of past growth can look out of place in a well-tended landscape. But Hoshizaki advises cutting off the dead or injured fronds only in the warm months and leaving them on during fall and winter.

“Pruning off the dead fronds can stimulate the plant to new growth that could be nipped by frost,” she explains.

Most ferns are frost-sensitive. If frost occurs, some varieties of ferns may withstand the freeze, depending on its severity and the plant. If the fronds are black and mushy looking, they have succumbed and can be removed. But the root zone may still be alive.

Hoshizaki advises waiting several months to see whether the plant regenerates before removing it from the ground and relegating it to the compost pile.

Another problem that can plague ferns is hungry slugs and snails tempted by the tender fronds. Combat them with nontoxic methods, including picking them off by hand, trapping them in a yeasty brew (such as beer) or applying snail bait around the plants.

When the plants become overgrown for their location, they can be trimmed back or divided during their growing season, with the exception of tree ferns, which can’t be divided. Other varieties can be lifted from the soil, carefully separated into several plants, each with growing points, and replanted or potted. Some ferns used in flower arrangements can be pruned and shaped as the fronds are harvested.

Barbara Joe Hoshizaki will share her knowledge of ferns at a free lecture Nov. 16 from 9:30 a.m. to 11 a.m. at Sherman Gardens, 2647 E. Coast Highway, Corona del Mar.

(BEGIN TEXT OF INFOBOX / INFOGRAPHIC)

Popular Varieties

Botanist Barbara Joe Hoshizaki says ferns are among the most popular garden plants. She says these varieties thrive in Orange County conditions:

Adiantum (maidenhair)

Aglamorpha cornans

Asplenium nidus (bird’s nest)

Cyathea cooperi (Australian tree fern)

Davallia trichomanoides (squirrel’s foot)

Nephrolepis exalta ‘Bostoniensis’ (Boston fern)

Platycerium (staghorn)

Pteris (brake)