Good Timing for Good Gardening

If you have an oak tree or an apple tree, this column is for you. If you have neither, read on nevertheless for seasonal ideas that generalize to other gardening processes.

The first concept of value is that timing is an essential strategy for successful gardening. Our plants operate on a natural cycle that waits for no gardener.

Apple Trees

Right now (the end of June) is the year’s last opportunity to maximize the yield of your apple trees. This time-sensitive task involves thinning your apples to allow each of the remaining apples to develop its greatest size and sweetness.

You can begin thinning apples a short time after the blossom drop when small apples appear, up to when the apples are no larger than table tennis balls. Once they grow beyond that size, thinning is not as effective.

Apple trees will thin themselves: the “June drop” is Nature’s way to produce larger fruits and avoid broken branches.

Commercial growers use chemicals for thinning, but hand thinning is practical for small home orchards. The largest young apples are the “king apples,” from the earliest blossoms. Use pruners or small clippers to remove the smaller fruits to so that the remaining fruits are about six inches apart. Let them drop then rake them for disposal. This might seem brutal but the harvest will be gratifying.

Oak Trees

During the July–November period, California Oakworms (Phryganidia californica) attack our Coast Live Oaks (Quercus agrifolia). The infestations vary in severity, but in a bad year the caterpillar-like larva of the Oakworm can defoliate a tree severely and provide a nasty display for the homeowner as well.

Some experts say Oakworm attacks are natural occurrences that rarely cause permanent damage to otherwise healthy oak trees. During last Saturday’s Garden Faire, however, I spoke with James Neve of Tree Solutions, who says homeowners need not suffer the presence of these insects and their droppings (frass), and their trees need not suffer defoliation. He recommends watching for the presence of oakworms in mid-July by placing a white paper plate under the tree’s branches and checking for frass. If the pests show up, consider whether spraying or injecting a biological control would be indicated.

Tree Solutions sprays with “Bt.” (Bacillus thuringiensis) or Pyrethrum (derived from Chrysanthemum flowers) or injects with Abamectin (derived from a soil bacterium). The University of California’s Integrated Pest Management program recommends these sprays and also a commercial product, Spinosad. A regular reader of this column reports good results with Spinosad. Most garden centers have these controls and spray equipment for do-it-yourselfers.

Other timely tasks: deadhead your roses, propagate your favorite woody plants from softwood cuttings, and above all, hydrate your plants during these hot and dry days.


For good, reliable information about the California Oakworm, visit the University of California’s Agriculture and Natural Resources website by clicking here.

For the commercial website of Tree Solutions (serving the Monterey Bay area), click here. (This is a free plug for a good business.)

Enjoy your garden.

Rock Gardening

In the garden, one thing always seems to lead to another.

I began by thinning one plant that had begun to crowd a bed in my garden. The plant is the Rain Lily (Zephyranthes candida), a low-growing bulb in the Amaryllis family, native to South America. It has grassy foliage, evergreen in the Monterey Bay area, and six-petal blossoms, white with a pink wash. (Pink blossoms are more common in the genus.)

After a few seasons in the ground, the Rain Lily generates many small bulbs and spreads happily. My original one-gallon clump expanded to fill nearly half of a semi-circular bed about thirty-feet in diameter.

I gathered hundreds of bulbs to share on June 23rd through the Garden Exchange at The Garden Faire (

That project created open space in that prominent front yard bed, and the opportunity to rethink its design. A rock garden seemed an obvious choice: the bed is already mounded and has a few largish boulders.

My preliminary inquiries into rock garden design revealed that this bed doesn’t qualify as a rock garden, but is instead a “rockery.” A rock garden has particular soil, rocks, and plants; a rockery is simply any planting bed with decorative rocks.

Serious rock gardeners study instances in which plants grow in a rocky environment. This occurs typically in a mountainous region, which will have high elevation, rocky ledges on sloping sites, rock outcroppings on more level land, and crevices, which are narrow, soil-filled spaces between rocks. The soil in such regions typically will be poor in nutrients and fast to drain. The climate usually will be windy and marked by much sun exposure.

The plants in a natural rock garden will have evolved to survive in those relatively hard conditions. The classic rock garden plants are called “alpines,” meaning plants that grow in The Alps, one of the great mountain range systems of Europe. These plants could be herbaceous or woody, and grow up to about one foot high.

Another category of rock garden plants includes small rock (“saxatile”) plants, which grow in rocky sites at lower elevations. These plants are easier than alpines to grow in most residential gardens because the gardener doesn’t need to recreate the uncommon conditions of a mountainous environment.

A popular feature for rock gardens is the scree bed, an area of loose rocks and stones that might occur at the bottom of a slope, perhaps deposited there by a landslide. A larger rock garden might have a sand bed, an acid heath bed, an “alpine meadow, or a boggy area beside a pond or stream.

A rock garden could succeed in a small setting as well, making this interesting naturalistic design concept adaptable for placement in gardens of all sizes.


A small rock garden could be created in a container. An appropriate container would be a hypertufa trough, which you can build yourself. Here are instructions from Fine Gardening magazine.

If you have larger project in mind, take the time to research the basic concepts, to be sure you are on the right track and won’t end up with a rockery instead of a rock garden. There are good books on the subject. Here are three that are available on

Rock Garden Design and Construction, by North American Rock Garden Society (2003)

The Serious Gardener: Rock Gardens (New York Botanical Gardens), by Ann Halpin and Robert Bartomonei (1997)

The Rock Garden Plant Primer: Easy, Small Plants for Containers, Patios, and the Open Garden, by C. Gray-Wilson (2009)

Anatomy of the Garden

Many gardens begin as level rectangles, with a residence more or less in the middle. It doesn’t have to be that way.

If your garden has natural changes of elevation or an irregularly shaped boundary, or both, you could have an interesting context for your garden design.

Dramatic departures from the level of course could be more challenging than inspiring. Workers on steeply sloped vineyards in Germany’s Rhine Valley hold on long ropes to keep from tumbling into the water.

Likewise, an oddly shaped plot could be more trouble than help. Municipal regulations generally prohibit building on small parcels of very unusual form, but such a parcel could accommodate a community garden.

If your garden amounts to a level rectangle, and consequently lacks interest, consider your options for creating elevation changes.

Below-grade elevation change possibilities include a swimming pool, a naturalistic pond, a bog garden (more shallow than a pond) and a rain garden (which collects rainwater and lets it seep into the ground). A swimming pool is mostly a recreational resource, but the other three offer interesting gardening possibilities.

For very large parcels, another below-grade option is the ha-ha. This is a ditch between a garden and a natural area, intended to keep domestic or wild livestock from straying into the garden. The ha-ha typically runs across the line from the residence to the natural area in the distance.

Above-grade elevation changes include raised beds, berms, terraces and sculpted landscapes.

Raised beds are usually rectangular, rising only a few inches above grade, primarily to improve drainage. They could be simple low mounds or might have low walls of wood or other materials. A raised bed also could be about table height, to raise the planting surface for the gardener’s convenience. Such beds are sometimes made for accessible gardening by gardeners with physical limitations.

Raised Beds - Corten

Berms are like large raised beds. They generally are eighteen to twenty-four inches high, curved for a natural look, four or five times as long as wide, and with sloping sides. They could provide higher quality soil (imported), superior drainage, or just visual interest.

For a short article on creating and using berms in the landscape, click here.

Terraces are similar to steps, and, like steps, provide one or more level areas to ease the transition from one elevation to another. They also have aesthetic value when well designed, and can improve the visibility of ornamental plants.

To view an unusual example of a terraced landscape (a rice field in China), click here.

Sculpted landscapes, above- or below-grade, are typically large-scale imaginative earthen constructions intended primarily for visual interest.

A fine example of a sculpted landscape can be seen at the WiIlliam J. Clinton Presidential Center (click here).

These possible elements of the landscape are not difficult or very expensive to accomplish, and could transform a flat rectangular garden into an interesting landscape. They also offer a fine opportunity for creativity in garden design, complementing the core activities of plant selection and placement.

Enjoy your garden!

Click to Enlarge

These clustered raised beds are made of Corten steel for long-term use.


Touring Exceptional Gardens

Recently, I wrote about the Garden Conservancy’s Open Days Program, which provides tours of exceptional private gardens. Since then, I visited two clusters of four private gardens south of the San Francisco Bay area.

Some gardens were the product of devoted gardeners who were pleased to dialog with the visitors about their gardens and specific plants and other features. These homeowners clearly enjoyed hands-on gardening.

Other gardens were the products of the designer, the installation contractor and the maintenance crew. The homeowners were more clients and admirers and satisfied with owning a showcase.

Here are some highlights of these tours.

  • A narrow, south-facing side yard with espaliered fruit trees next to the house and raised beds along the fence. Efficient and productive use of a space that is often wasted.
  • Espaliered Apple TreesA cluster of sixteen raised beds of Corten steel, each about five by ten feet, with four-foot aisles. Major commitment to growing edibles and ornamentals.
  • An outdoor dining room with seating for twenty-four, on a brick patio under an arbor of pollarded plane trees (Platanus × acerifolia). Nice
  • Dining Room for 24 Guests, Brick PatioA twenty-foot tall weeping Atlas Cedar (Cedrus atlantica ‘Glauca ‘Pendula’) next to a koi pond. (I must remove the five-foot specimen that eventually will outgrow its space in my garden.)
  • Weeping Atlas CedarA sharply sloped area at the back of the property with a twenty by forty foot children’s play yard on stilts, a zip line and a newly planted vineyard. Good use of a difficult part of the landscape.

Many visitors focused on individual plants, particularly those in current fashion, e.g., Rosa ‘Sally Holmes’ and R. ‘Spice so Nice’ growing on a fence, several Oakleaf Hydrangeas (Hydrangea quericifolia), a large Matilija poppy (Romney coulteri), and a great number of ornamental grasses.

The benefits of touring private gardens also include seeing combinations and swaths of selected plants, examining the design of ornamental borders and studying the overall layout of the landscape, including hardscape features and garden art. There is much to learn from other people’s gardens.

For info on future Open Days, visit

Exceptional Gardens

Avid gardeners have a small number of valuable champions. Among them are public botanical gardens and arboreta, and private residential gardens of exceptional quality.

The Garden Conservancy is an organization that works to make exceptional residential gardens accessible to the public. This non-profit organization was established in 1989 by Frank Cabot, a distinguished American gardener who passed away late last year.

The Conservancy conducts two primary programs, as follows:

The Garden Preservation Program

Here, the Conservancy identifies exceptional gardens and works to help them survive and prosper. It has extended its assistance to some ninety gardens, to date, supporting their transition from private to non-profit ownership and management. The Conservancy has continuing relationship with sixteen gardens in the United States, of which two are in northern California.

One of these is the Ruth Bancroft Garden in Walnut Creek, which is in fact the first garden of the Conservancy’s Preservation Program. This is a forty-year-old, three-acre garden of succulents, the long-term project of Ruth Bancroft (b. 1908) who continues her interest in the garden. The garden is managed by a non-profit organization, which maintains a regular schedule of days for public visits. For more information, visit the website

The other Preservation Program in California is the Gardens of Alcatraz, in San Francisco Bay. The prisoners and staff of the federal prison on Alcatraz Island developed the gardens originally; they are maintained today by a partnership that includes the Garden Conservancy, the Golden Gate National Parks Conservancy and the National Park Service. Admission to the gardens is free of charge, but visits involve a private ferry that does charge for its services. For information:

These two gardens are interesting and memorable destinations for daytrips by Monterey Bay area gardeners.

The Open Days Program

The Garden Conservancy also facilitates access to many additional private gardens, which are selected by the Conservancy for inclusion in its Open Days program. This program offers self-guided tours to private gardens during the spring, summer and fall months. The organization groups gardens in clusters within a given area, for the convenience of visitors. Visitors are welcome at any time within the announced schedule; the admission fee is $5 per garden. The Conservancy offers the Open Days Directory, a national publication that lists Open Days and participating gardens with garden descriptions, open hours, and directions.

This weekend, for example, includes Open Days on Saturday, June 2 for a cluster of four gardens in the San Francisco Peninsula area (Atherton, Palo Alto, Portola Valley), and on Sunday, June 3 for a cluster of gardens in the Telegraph Hill area of San Francisco.

For information on the Garden Conservancy’s programs, visit

More: Return to this page after June 2, 2012 for notes from the Open Days gardens of the SF peninsula.