Monday Oct 02, 2023

Tom Karwin, On Gardening | Front-of-wall options – The Mercury News

Care for your garden

Composting organic waste from the garden and kitchen is surely a good practice, but it involves more labor than I could provide. My garden’s nutrient level seems sufficient, resulting in part from the slow decomposition of many yards of wood chips imported over the years as mulch.

Having come to that conclusion, I removed the large three-bin composting structure behind my garage, freeing the area for a new raised bed. This bed is 7 feet deep, 18 feet wide, against the garage’s rear wall, which is about 15 feet high.

This space connects to an existing bed of Mexican succulent plants along the side of the garage, so for thematic continuity the new bed will be focused on Mexican/South American plants.

The new bed is large enough to accommodate many plants, but the initial challenge is for the design to include enough height to take advantage of the garage wall. Coincidentally, one of my garden coaching clients has a similar opportunity to showcase a tall specimen plant in front of a windowless wall of their residence. I will explore the possibilities in a future column.

The San Pedro cactus blossoms in the fall. (Lars — Wikimedia Commons)
The San Pedro cactus can develop an impressive cluster.(Forest & Kim Starr — Contributed)

An initial thought for a tall plant in my new planting bed has been a cluster of three San Pedro cacti (Echinopsis pachanoi, also called Trichocereus pachanoi). This plant, native to several South American areas, is popular for its ornamental value and its height, growing 10-to-20 feet tall. This plant came to mind because a landscaper friend offered three specimens, which were surplus to her work.

This option combines great height, attractive appearance, thematically on target, and free!

Then, another friend brought the news that the Santa Cruz City Council had very recently revised its two-year old policy to decriminalize psychedelic plants and fungi by making an exception of plants that naturally contain mescaline, known for its hallucinogenic effects. This action effectively recriminalizes such plants, including the San Pedro cactus and peyote cactus (Lophophora williamsii).

There are many plants and fungi with psychoactive properties. Visit Wikipedia for a list if you are interested. The City Council acted to recriminalize mescaline-containing plants because, according to the resolution, decriminalizing plants including peyote “can be disruptive to the nation-wide strategy driven by Native American people to protect, conserve, and ensure the spiritual and ecological sustainability of peyote.”

I don’t understand the disruption problem, and I don’t have a problem with the policy, but it might have allowed ornamental uses of at least the San Pedro cactus.

There are many good choices for a specimen plant in front of a blank wall. If you have good experiences or ideas for such a showcase selection, send them for inclusion in this study.

Advance your gardening knowledge

The Pacific Horticultural Society’ YouTube Channel has an intriguing growing collection of video presentations of particular interest to California gardeners. This collection includes the mini-documentary series, Landscapes of Change, “documenting stories of climate resilience in horticulture, landscape design, restoration, and applications of research. New models that impact green infrastructure and industry, explore real and human challenges, and the amazing professionals who are driving innovation.”

This series begins with the “The Portreo Hill Eco-Patch,” the story of a unique group of people in one neighborhood in a big city, who all gathered around one very special idea. Episode 1 of this story premieres at 4 p.m. Oct. 14.

To view Landscape of Change and other Pacific Horticulture offerings, visit and search for Pacific Horticulture.

Enrich your gardening days

Given the enormous and growing number of garden-worthy plants, many gardeners rely upon the plants with which they are already familiar, and that are readily available from garden centers and big box stores. Some gardeners, however, are attracted to different plants, which might be described in two categories: new and rare.

The new category includes recently introduced cultivars, which are either selected varieties of plant species or hybrids of two or more compatible species. Plant nurseries eagerly present each season’s new introductions of roses, daylilies, irises, and other popular genera. These offerings often have good physical attributes and appealing blossom colors, both of which are desired by plant collectors.

The rare category includes species that are unusual or uncommon in garden settings. Typical garden plants are angiosperms, which produce flowers and seeds. These plants include 13,000 known genera and 300,000 known species. That’s a large universe that includes a small number of familiar garden plants and a very large number of plants that most gardeners have not encountered.

All unfamiliar plants are not always desirable in the garden. The rare category can be divided into garden-worthy and “not garden-worthy.” The rejects include plants unsuitable for a given garden environment and some that are simply not attractive. These are clearly subjective criteria related to specific gardens and gardeners, but they are nevertheless important.

This leisurely wander through the plant kingdom brings us to a strategy for discovering rare plants that could succeed in your garden and that you would find interesting, suitable and (hopefully) attractive companions to your garden.

This not an easy task. Most gardeners rely on serendipity, discovering rare plants by visiting other gardens, scanning garden magazines and websites, or interacting with other gardeners.

A more organized strategy for finding rare plants for your garden could begin by reviewing someone else’s list of rare plants. Many such lists are available in the San Francisco Botanical Garden’s Helen Crocker Russell Library of Horticulture, describe as “northern California’s most comprehensive horticultural library … with 27,000 volumes and 250 current plant and garden periodicals.”

Visit, click on “Search Collection” and search for “rare plants.” These steps will result in an impressive 85 hits on books on the topic, representing various slices of the botanical world. These hits are likely to include some that relate to your interests.

You could travel to San Francisco for a visit to this library (see or search to determine availability of the book or books you’ve selected.

Prediction: this process could present plants that are not as rare as you expect, or strongly appealing plants that you can’t find. Or it could lead to new plants that provide bragging rights and enrich your gardening days.

Tom Karwin is past president of Friends of the UC Santa Cruz Arboretum, Monterey Bay Area Cactus & Succulent Society, and Monterey Bay Iris Society, and a Lifetime UC Master Gardener. He is now a board member and garden coach for the Santa Cruz Hostel Society.

Tom Karwin, On Gardening | Front-of-wall options

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