Tom Karwin, On Gardening | Thankful for plants of the Mediterranean – Santa Cruz Sentinel

Take care of your garden

This week’s edition for the current planting season focuses on the Mediterranean, which includes 17 European, African and Asian countries around the Mediterranean, as well as the Madeira Archipelago and the Canary Islands, which are close to the Atlantic.

Gardeners in Monterey Bay prefer plants that are native to a Mediterranean climate characterized by mild to cool, rainy winters and warm to hot, dry summers. This climate is named for the Mediterranean region, but that designation can be distracting as similar climates occur on the coast of California, the south coast of South Africa, the west coast of central Chile, and the southwestern areas of Australia.

A better and more meaningful name for this climate is “summer dry”.

Each of these summer-dry regions has characteristic native plants, so that the thematic garden design could dedicate an area within the landscape to the plants of one of these regions. This plan invites you to present the plants of a selected region and benefit from their common cultural requirements. UC Santa Cruz’s Arboretum & Botanic Garden ( and UC Berkeley Botanical Garden ( are examples of this approach in public gardens.

Public botanical gardens often organize their outdoor areas according to geographic areas such as the summer arid areas. Some botanical gardens have an environment for, and an interest in, Asian gardens that combine distinctive plants and a distinctive landscape style. The Huntington Botanical Gardens ( include both Japanese and Chinese gardens.

The total land area of ​​the Mediterranean has not been given in the literature I have seen, probably because it does not coincide with well-documented political boundaries. The various summer-arid climates make up a small (perhaps 5%) part of the total arable land in the world, that is, land suitable for growing crops. That makes them especially for gardeners.

The dry summer climate in the Mediterranean region shows significant differences due to differences in altitude and other factors. Some gardeners have also described three sub-types of this climate: cool, warm, and hot summers.

Given this variation, it is unlikely that a Mediterranean region of a garden, whether small or large, will group companion plants, that is, those that will grow together in nature. While it would be possible to develop such a garden, it is enough to group plants that are native to the area to illustrate the category and take into account their common cultural needs.

The most famous plants of the Mediterranean area are lavender (Lavendula), figs (Ficus carica) and olives (Olea europaea). There are many other, lesser-known genera that are native to this botanically rich region.

The following plants, chosen at random from my garden, are a small extract from the diverse horticulture of the Mediterranean region. Hopefully they will suggest the character and interest of the area’s gardeners in including a selection of the area’s plants in their own gardens.

European gray sedge (Carex divulsa). This evergreen, lumpy, grassy plant enjoys partial shade, tolerates swampy soils, and once established is quite drought resistant. It grows to 2 × 2 feet or more, spreads slowly, and makes an attractive addition to many other plants. It has been mistaken for Native California and marketed as the Berkeley Sedge, but it is a common European species.

Rose Rose (Cistus spp.). Native to Spain and Portugal, this plant hybridizes naturally, has been popular with gardeners since 1860 and is available in 19 species and numerous varieties. Popular varieties are the Silver Pink Rock Rose (C. argenteus ‘Silver Pink’), the White Rock Rose (C. ladanifer ‘Blanche’) and the Crimson-Spot Rock Rose (C. ladanifer maculatus). These are short-lived plants that produce flowers in June and July, sow abundantly and easily reproduce by cuttings. Withdrawing after flowering will help maintain a bushy shape.

Corsican Hellebore (Helleborus argutifolius). This is a sturdy plant with pale green, cup-shaped flowers in late winter to early spring and attractive leathery foliage. It grows 4 feet high and 3 feet wide, making it taller than most Hellebores, which are typically only 18 inches tall. Cut back after flowering, it forms attractive new shoots in autumn. This species is known for sowing numerous new plants each season.

Madeira Island Geranium (Geranium maderense). This largest of the geranium species is a 3-foot by 3-foot bineenial that displays attractive foliage between flowering years. When it blooms, it displays a staggering mass of 1 inch wide, lavender-pink, dark-centered flowers that grow up to 1.5 meters tall. There is also a white-flowered form (G. m. ‘Alba’).

Large Bearded Iris (Iris’ That’s all people). The iris family includes several versions of bearded iris (grouped by height), variations of Iris germanica, a natural hybrid of I. pallida and I. variegata. This plant was first identified in 1753 and has been crossed into over 60,000 varieties with an extraordinary range of colors, color combinations, and flower shapes. Iris lovers are challenged to keep up with the latest introductions. One of my favorites is ‘That’s All Folks,’ which crossed in Santa Cruz and won many awards, including the high-ranking Dykes medal.

Colorful lavender (Lavandula x allardii ‘Meerlo’). As mentioned earlier, lavender has long been associated with the Mediterranean and valued for its appearance, scent and moth deterrent. Some popular species are English lavender (L. angustifolia, which is native to Spain, France, Italy, Croatia), French lavender (L. dentata), and Spanish lavender (L. stoechas). There are several English lavender plants in my garden, but I particularly like L. x allardii ‘Meerlo’, a selection made from the cross of L dentata x L. latifila.

Giant white squill (Urginea maritima / Drimia maritima). This plant is a real performer. It produces wide, 18-inch leaves from November through summer. The leaves then fade, and from summer through fall the plant forms a four-foot peduncle with an inflorescence of a large number (who counts?) Star-shaped white flowers that attract birds and bees. In this process, the large onion (up to 12 feet wide) divides dichotomously, enlarges to two onions, and eventually forms a large lump.

Expand your gardening knowledge

Upcoming webinars:

The Cactus & Succulent Society of America will present the “Yuccas” webinar on Saturday at 10 am. Yuccas are generally large evergreen plants native to hot and arid areas of Mexico and the Caribbean. They are popular for dramatic elements in the landscape and large displays of white or whitish flowers. Brian Kemble, curator at Ruth Bancroft Garden in Walnut Creek and a prolific writer and speaker on succulents, will share his knowledge of yuccas growing in habitats. To register for this free event, visit

The Garden Conservancy will present the webinar “Beyond Wild: Gardens and Landscapes” on December 2nd at 11:00 am. Garden designer Raymond Jungles will describe his most impactful design projects, which will also be featured in his new book with the same title. To enroll, visit, click Virtual Programs, then click Fall 2021 Literary Series. For the upcoming Garden Conservancy webinars, click on “Virtual Programs for Winter / Spring 2021”.

The UC Botanical Garden in Berkeley has announced its webinar program for December. Early offers include the “Virtual December Butterfly Walk – Beyond the Bay Area” (11am, December 5th) and “Winter Conifers Virtual Tour” (3pm, December 7th). For information on these free events and other virtual programs, visit, click Programs, then click Programs & Workshops.

Enrich your garden days

Consider developing your own collection of Mediterranean plants. There are both familiar and delightfully diverse plants to brighten up your garden.

Enjoy your garden!

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 (Certified 1999-2009). Today he is a board member and garden coach of the Santa Cruz Hostel Society. To view photos from his garden daily, To search an archive of previous On Gardening columns, visit Contact him with comments or questions at [email protected]

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