Tom Karwin, On Gardening | The matrix planting model

Scarlet Coyote Mint (Monardella macrantha). This is the only Monardella with red flowers, found in the Santa Lucia Range of Monterey County. Other species of the genus have white to lavender flowers. These low, mat-forming plants are difficult to establish in gardens but give much pleasure should they thrive. Las Pilitas Nursery reports: "Hummingbirds risk their lives delivering pollen to this flower." Photo taken at the Regional Parks Botanic Garden near Berkeley. (Courtesy John Rusk via Wikimedia Commons) — Scarlet Coyote Mint (Monardella macrantha). This is the only Monardella with red flowers, found in the Santa Lucia Range of Monterey County. Other species of the genus have white to lavender flowers. These low, mat-forming plants are difficult to establish in gardens but give much pleasure should they thrive. Las Pilitas Nursery reports: “Hummingbirds risk their lives delivering pollen to this flower.” Photo taken at the Regional Parks Botanic Garden near Berkeley. (Courtesy John Rusk via Wikimedia Commons)

By Tom Karwin | [email protected] | Santa Cruz Sentinel

PUBLISHED: May 23, 2024 at 1:21 PM PST

Scarlet Coyote Mint (Monardella macrantha). This is the only Monardella with red flowers, found in the Santa Lucia Range of Monterey County. Other species of the genus have white to lavender flowers. These low, mat-forming plants are difficult to establish in gardens but give much pleasure should they thrive. Las Pilitas Nursery reports: "Hummingbirds risk their lives delivering pollen to this flower." Photo taken at the Regional Parks Botanic Garden near Berkeley. (Courtesy John Rusk via Wikimedia Commons)

Coyote Mint (Monardella villosa). A spreading subshrub with fragrant mint-scented foliage and delicate lavender flowers. Summer’s blooms are attractive to bees and butterflies. It is drought tolerant, but bloom and foliage quality improve with some summer irrigation. Light pruning helps maintain a neat appearance. Photo taken at Almaden Quicksilver County Park in San Jose. (Courtesy Eugene Zelenko via Wikimedia Commons)

Narrowleaf Milkweed (Asclepias fascicularis). This perennial grows 3 feet tall and is dormant in winter. It is the most important host plant for monarch butterflies in California, attracting them and hosting their caterpillars. It blooms from summer to fall, with lavender or pinkish-white flowers with interesting button shapes. The pods split open to spill seeds with silky hairs that can carry the seeds through the air. Uses of a pesticide on or around the plant will be fatal to the caterpillars. (Courtesy Bjorn S. via Wikimedia COmmons)

Canyon Prince Wild Rye (Leymus condensatus 'Canyon Prince'). This medium-size grass has striking blue-green foliage that adds interest and color contrast to the landscape. It grows 2-3 feet tall, and up to 5 feet tall with regular watering. Erect flower stalks rise 12 feet above the foliage in late summer and are topped with clusters of spikes of wheat-colored flowers. Cut back every few years for the best appearance. It spreads by short rhizomes and can colonize large areas. Its growth can be restricted by removing or blocking the rhizomes. Photo taken at Rancho Santa Ana Botanic Garden in Claremont. (Courtesy Stickpen via Wikimedia Commons)

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Our recent column introduced matrix planting, a naturalistic approach to designing a garden bed, or a full garden. To review that column, “matrix planting ideas,” visit www.santacruzsentinel.com and search for Karwin.

That column referred to an inexpensive digital book, “A Brief Guide to Matrix Garden Design,” downloadable from www.monarchgard.com/gardenguides.html. This book provides brief principles and graphic demonstrations of matrix planting for a 10-foot-by-10-foot garden bed design. It provides useful basic information for planning and lists plants for a matrix garden.

Matrix planting involves three layers of plants: groundcovers, smaller and larger seasonal perennials. It does not include annual plants but could include architectural perennials (shrubs, and trees), if that works in your garden.

Piet Oudolf, who has popularized this approach to naturalistic garden design, does not include trees and shrubs in his plans. (See advancing your knowledge below for more about Oudolf).

While a matrix planting could be based on a wide variety of plants, emphasizing plants native to the garden’s specific region yields benefits: Successful cultivation, support of the local wildlife, ready availability, and design integrity.

Accordingly, we have identified plants native to the Monterey Bay area that could be included in a matrix planting, as outlined in the digital book cited above. We have selected plants with visual appeal from our perspective, and acknowledge that gardeners could prefer other selections.

Our plant list includes forbs (flowering plants other than grasses) and graminoids (true grasses, sedges, and rushes). Both categories are native to the Monterey Bay area.

Included are flower colors and bloom seasons for each forb, for reference in planning color combinations and coordinating seasons for extended blooming. The general approach to matrix garden design includes clusters of three grasses or forbs, placed informally, with the largest in the center of the bed, plus groundcover plants covering the spaces between clusters.

For filling a 10-foot-by-10-foot garden bed, the gardener would need groundcover plants (depending on the sizes of groundcovers and other plants), plus about 10 three-plant clusters of selected plants. This dense planting requires acquiring and installing many plants, which when mature will crowd out weeds. Costs and efforts could be minimized by purchasing plugs or small plants.

Today’s photo gallery includes samples from four categories of plants. The photos have been downloaded from Wikimedia Commons (a valuable resource) and the captions are edited versions of information from Calscape.org.

For more detailed information on these plants, visit calscape.org and search for the plant’s common or botanical name. The site’s database provides multiple photos of most plants, plus lists of nurseries that offer the plants.

Grasses and Forbs up to 1 foot (groundcover options)

• Blue Grama (Bouteloua gracilis), groundcover plant in “A Brief Guide to Matrix Garden Design.”

• Scarlet Coyote Mint (Monardella macrantha) – red flowers, summer and fall.

• Silver Carpet Aster (Corethrogyne filaginifolia ‘Silver Carpet’) – lavender, pink flowers; summer, fall, winter.

• Foothill Sedge (Carex tumulicola), a groundcover plant option.

Grasses

• Purple Three Awn (Aristida purpurea).

• California oatgrass (Danthonia californica).

• Canyon Prince Wild Rye (Elymus condensatus ‘Canyon Prince’).

• Red Fescue (Festuca rubra).

• Purple Needlegrass (Stipa Pulchra), which is California’s state grass.

Perennials about 3 feet high

• Narrowleaf Milkweed (Asclepias fascicularis) – lavender, pink, white flowers; summer, fall.

• Sticky Cinquefoil (Drymocallis glandulosa) – white or yellow flowers; spring, summer, fall.

• Golden Yarrow (Eriophyllum confertiflorum) – yellow flowers; winter, spring, summer.

• Coyote Mint (Monardella villosa) – pink, lavender flowers; summer.

• California Cudweed (Pseudognaphalium californicum) – Cream, White, Green flowers; winter, spring, summer.

Perennials 4 to 6 feet high

• American Vervain, Blue Vervain (Verbena hastata) – blue, purple flowers; summer.

• Canyon Sunflower (Venegasia carpesioides) – yellow flowers; winter, spring.

• Prince’s Plume (Stanleya pinnata) – yellow flowers; spring summer, fall.

• Western Goldenrod (Solidago lepida) – yellow flowers; spring summer, fall.

• Kellogg’s yampah (Perideridia kelloggii) – white, cream flowers; summer.

• Hooker’s Evening Primrose (Oenothera elata ssp. hookeri) – yellow flowers; summer, fall.

• Bolander’s Goldenaster (Heterotheca sessiliflora ssp. bolanderi) – yellow flowers; summer.

Advancing your knowledge

A 40-minute documentary, “The Art of the Garden,” describes the work of Dutch garden designer Piet Oudolf. Forty years ago, he rebelled against the use of annuals in favor of perennials and led the New Perennial Movement, which is the basis of the current matrix planning concept. This documentary can be viewed online at tinyurl.com/y8ke6hwr.

More about Piet Oudolf is available on Wikipedia (en.wikipedia.org/wiki/Piet_Oudolf). This web page includes links to his design projects, including the most visited project: the High Line Garden in New York City.

Consider matrix planting and enjoy your garden!

Tom Karwin is a past president of Friends of the UC Santa Cruz Arboretum and the Monterey Bay Iris Society, a past president and Lifetime Member of the Monterey Bay Area Cactus & Succulent Society, and a Lifetime UC Master Gardener (Certified 1999-2009). He is now a board member of the Santa Cruz Hostel Society, and active with the Pacific Horticultural Society. To view photos from his garden, https://www.facebook.com/ongardeningcom-566511763375123/ . For garden coaching info and an archive of On Gardening columns, visit ongardening.com for earlier columns or visit www.santacruzsentinel.com/ and search for “Karwin” for more recent columns. Email comments or questions to [email protected].