There are shrub ferns and tree ferns and epiphytic, or tree-dwelling, ferns. Ferns may be used as drought-tolerant, quick-spreading ground covers when shady planters need to be filled in. There are ferns custom-made for hanging baskets, and ferns that look their best as potted plants. There is even an aquatic fern that resembles a four-leaf clover and another that makes its own fertilizer.
Nearly all ferns are capable of withstanding periods of environmental stress because they have rhizomes. A rhizome is a thick horizontal stem, growing underground or on the soil surface, with roots on its bottom and leaves or fronds on its top. If all its leaves and roots should die suddenly, a rhizome will start new leaf and root growth almost immediately. Iris and agapanthus are two common ornamental plants with rhizomes.
In addition to rhizomes, many ferns have either leathery or hairy fronds – characteristics that may provide insulation from the heat, if not drought tolerance.
Ferns are recognized by their new fronds, or croziers, which resemble tiny fiddle necks. On the underside of mature fern fronds are brown bumps, each of which contains thousands of spores – the fern’s reproductive structures.
Tree ferns probably are the most distinctive members of this group. Their trunks actually are vertical rhizomes, which must be kept moist for the plants to flourish. Growing to a height of 50 feet in their Australian habitat, they do not reach more than 15 or 20 feet in Los Angeles. The Tasmanian tree fern (Dicksonia antaractica) is hardy enough to survive snow storms in its native land.
The holly leaf fern (Cyrtomium falcatum) exhibits dense, shrub-like growth to a height and width of 3 feet. It tolerates more exposure to both direct sun and winter cold than most ferns. The lady fern (Athyrium filix- feminia) grows nearly as tall, spreads out as a ground cover but is more sensitive to the elements. Another spreading fern, of smaller stature but greater durability, is the leather fern (Rumohra adiantiformis).
Perhaps the most common ground cover fern is Nephrolepis cordifolia, the sword fern, which has stiff, upright fronds. It is related closely to the Boston fern, an indoor plant with arching fronds that should be placed in the most humid part of the house and given a constant diet of liquid nitrogen.
One of the most fascinating sights at the Huntington Gardens in San Marino is a gigantic stag-horn fern growing on the trunk of a several-hundred- year-old California live oak. Native to the tropics, staghorn ferns (Platycerium spp.) can be adapted to most Los Angeles gardens, as they easily survive freezing temperatures. These ferns – called staghorns because of their deeply lobed, antler-shaped fronds – are epiphytes, or tree-dwellers and, with some baling wire, may be attached to almost any tree trunk in your garden. Just make sure they get plenty of shade, regular misting and liquid fertilizer.
Another epiphyte of note is the bird’s nest fern (Asplenium nidus), which typically is grown as a potted plant. It is one of only a few ferns with whole, uncut leaves. It makes a dramatic statement in an entryway with its shiny, pale green fronds that can grow to 4 feet in length. The mother fern (Asplenium bulbiferum), like its cousin, has memorable coloration – yellow- green, black-veined fronds – and personality. It produces baby ferns, called bulbils, on its fronds that easily can be detached and grown into new plants.
There are two commonly grown water ferns: Marsilea and Azolla. Marsilea grows on the edge of water ponds and looks like the perfect four-leaf clover.
Azolla, a minute plant that spreads out like a mat, makes its own nitrogen through symbiosis with microscopic algae. Azolla turns red on and off during the year. Its growth is dense and it can take over a water garden. Before it gets out of control, scoop up the excess and spread it over your garden as nitrogen-rich mulch.
And don’t forget giant chain fern (Woodwardia fibriata), a California native.
By the way: Asparagus ferns are not ferns at all. They are in the same genus as the edible asparagus and are members of the lily family.
Ferns make an attractive understory to low-growing palms and cycads. Cycads, such as the so-called sago palm, actually are neither palms nor ferns, but a group unto themselves, “missing links” related to primitive conifers.
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Thin peaches and nectarines so that remaining fruit are separated by 3 inches on the branch; otherwise, fruit will not size properly and branches may
break from excessive weight.