GARDENING : Suburban Mass Transit System : Self-Seeding Plants Get a Free Ride in the Backyard

By JULIE BAWDEN DAVIS

March 9, 1996 12 AM PT

SPECIAL TO THE TIMES

Twenty years ago, Hortense Miller bought a gallon can of goldenrod at the nursery, planted it in her sprawling Laguna Beach garden and let it roam.

Today the plant’s striking yellow plumes appear all over her hillside garden.

Every November, lavender asters dot her landscape, thanks to a handful of roots she planted more than 10 years ago.

For Miller, who orchestrated what is considered one of the best private gardens in America, plants such as goldenrod and aster are a necessity.

“I have 2 1/2 acres, and it’s impossible to plant everything myself,” she says. “I’m fond of plants that know how to take care of themselves and multiply.”

Encouraging self-seeding and self-perpetuating plants can be done in any size garden. And there are a lot of benefits. Not only do self-seeding plants minimize labor and maintenance, but they also are an inexpensive way to garden.

“When things self-seed and self-perpetuate, you get a lot of little surprises,” says Bruce Berlin, a horticulturist at S&S; Seed Co., a Carpinteria wholesaler whose seeds are available at Orange County nurseries.

“Part of the enjoyment is going out and looking at all of the babies coming up all on their own,” he says. “It reminds you of the cycle of life.”

Another reward of self-perpetuating plants is that they know where to go, which saves you from researching the best locations.

“I planted some oxalis crassipes, which has pink and white blooms in summer, right outside the dining room window,” Miller says. “It left and went down to below the redwood. It’s remarkable how things move around; they know what they’re doing and always choose the best spot for themselves.”

Unlike overzealous gardeners who often space plants too closely, self-perpetuating plants are “clever about spacing themselves,” Miller says. “They rarely get too close and don’t need thinning.”

Many reseeding plants tend to have seeds that become airborne easily, although heavier seeds find their way around the garden thanks to birds and other animals. Other plants spread by above-ground or below-ground runners, which are spreading roots. Some have bulbs that multiply.

Certain plants spread so readily that horticulture experts warn against them.

“Plants like the Mexican evening primrose and Shasta daisy are so invasive they’ll become weeds and take over everything,” says Laguna Beach landscape architect Jana Ruzicka.

Before you introduce a plant into your garden, make sure it isn’t too pushy.

Plant flowers that reseed now, and they’ll go through a full life cycle and create a new line of plants by summer, Berlin says.

Although there are no guarantees that your plants will self-perpetuate, there are things you can do to encourage offspring.

Don’t use hybrids in the garden, because many won’t reseed, Ruzicka says.

Before the plants bloom, encourage a lot of seeds by feeding the plants with a fertilizer high in phosphorus and potassium, Berlin says. Then water well until they are in full bloom, at which point you should cut back on watering.

“Limiting water causes plants to stress out,” Berlin says. “Stressed plants tend to produce more seed as a survival instinct.”

Once flowers are spent, it’s important not to deadhead. Let the seed mature and fall. Fortunately, many plants have attractive seed pods.

To check if seed is ready to fall, shake a stem, Berlin says. If the seed is easily dislodged, it is ripe.

Once the seed falls, it must hit fertile soil. “Seeds will wash away from cement-like soil,” Berlin says. Regularly cultivate and amend your soil to make it a loose, welcome host for fallen seed.

Miller shreds plant cuttings and applies them in the form of mulch. Homemade and store compost are also good amendments.

Periodically fertilizing with an organic fertilizer, such as cottonseed meal or blood meal, is also a good idea, Ruzicka says.

Unfortunately, all the planning and amending in the world won’t guarantee that your plants will self-perpetuate.

“It’s nothing you can calculate,” Ruzick says. “If a plant begins growing in cracks at the base of a wall or in a drainage hole, that’s something that can only happen by itself. Many people want to control their gardens, but the truth is very humbling. Gardens have a life of their own.”

Just ask Miller how independent and single-minded plants can be. On a two-story high bank behind her house, she planted ice plant.

“Today, not a bit of the ice plant is left,” she says. “Instead, the hill is covered with climbing aloe, asparagus fern, maidenhair fern and creeping fig.

“It’s very pretty, but I have no idea how it all got there,” she says. “The way things move is marvelous.”

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Self-Perpetuating Plants

Many plants reseed and self-spread. Following is a sampling of such plants. Those with an asterisk should be used with caution, as they can become invasive.

* RESEEDERS

African daisy (Dimorphotheca aurantiaca)

Alyssum

Baby blue eyes (Nemophila menziesii)

Bluebells (Phacelia campanularia)

Borago (Borago officinalis)

Butterfly bush (Buddleia)

California poppy (Eschscholzia californica)

California sagebrush (Artemesia californica)

Clumping gazania (Gazania splendens)

Coreopsis (Coreopsis lanceolata)

Cosmos (Cosmos bipinnatus)