Blue oat grass

Helictotrichon sempervirens (Blue Oat Grass) sitting area by stone retaining wall in California garden with Lavender, and Caryopteris.

Blue oat grass with lavender

Grown well, blue oat grass (Helictotrichon sempervirens) is big on drama, its narrow, blue-green leaves forming a perfectly rounded dome when not crowded by other plants and older leaves providing a subtle infusion of tawny gold.  In early summer flowerheads arise on tall stalks two feet above the foliage, turning a matching golden color in late summer or fall.

A clump-forming ornamental bunchgrass, up to two feet tall and three feet wide at maturity, blue oat grass likes full sun near the coast, but seems to prefer part shade or afternoon shade inland. This grass must have good to excellent drainage, good air circulation, and not too much water in summer.  Even in winter, heavy rainfall may result in root rot if the plant is not kept free of excess dead leaves and other debris around the base.

Helictotrichon sempervirens (Blue Oat Grass) Gray foliage grass in California garden with Fremontodendron (Flannel Bush).

Young plants of blue oat grass with fremontia

This is a grass I do not cut back in fall or in spring, in large part because it looks good year round with a little maintenance.  This cool-season grass is evergreen to semi-evergreen where winters are mild.  It would, unnecessarily, look quite sad if cut back the two-thirds recommended for cool-season grasses in colder climates. Warm-season grasses (e.g., Leymus condensatus, Bouteloua gracilis), on the other hand, can be cut almost to the ground in early spring, look acceptable in butchered dormancy, and come back quickly in mid- to late spring or early summer.

In lieu of cutting back blue oat grass, I rake out old leaves with a steel rake two or three times a year.  This is a good reason for spacing these plants at least three feet apart (another reason is that wide spacing displays the full glory of their shape and size).  I lay a tarp around the plant to catch most of the old leaves that are raked out, but even then some of the very fine leaves are scattered about the garden. It’s a messy job, but easy to do, and the plant will thank you for it.

It’s important to know whether the grass you have is a cool-season or warm-season plant. Trimming cool-season grasses too harshly at any time of year may harm them irreparably. Cool-season grasses such as blue oat grass perform best where summers are not too hot and winters are not too cold.  If you garden in a hot southern or inland climate, afternoon shade is pretty much required.

Helictotrichon sempervirens is native to southwestern Europe, but thrives in any similar summer-dry climate if its simple needs are met.  Like many tough-leaved grasses, it seems to be reliably unpalatable to deer.

Arbutus

Arbutus unedo 'Elfin King' (Strawberry Tree) with fruit.

Arbutus unedo ‘Elfin King’ with fruit.

With evergreen, leathery, dark green leaves, showy clusters of tiny white spring flowers, small red berries in fall, and red-brown peeling bark, Arbutus menziesii is a signature tree of western North America.  Native to coastal evergreen forests from southern British Columbia to California, the western slopes of the Sierra Nevada, and the eastern slopes of the Coast Ranges, this tree has long been considered too difficult for most cultivated landscapes.  Commonly known as Pacific madrone, A. menziesii is available in small containers mostly from specialty nurseries and at native plant sales.

For best results, Arbutus menziesii should be set out in its permanent spot when the seedling is a foot or so tall.  Excellent drainage is essential.  Young trees seem to prefer the filtered shade of evergreen trees, but may not establish in full shade. They thrive in full sun along the coast and inland at higher elevations.  Water only to establish and do not fertilize.  Water and fertilizer will promote growth but make this plant more susceptible to disease.  Usually slow-growing to anywhere from fifteen to fifty feet tall, trees may reach over 100 feet at great age.

Arbutus unedo (Strawberry Tree) by gravel pathway with ornamental grasses in David Fross waterwise sustainable garden

Arbutus unedo (strawberry tree) by gravel pathway with ornamental grasses

Arbutus unedo, strawberry tree, is native to the Mediterranean Basin and parts of western Europe.  With evergreen, leathery, dark green leaves, drooping clusters of small rosy white flowers, largish red fruits, and peeling reddish brown bark, strawberry tree is similar in many ways to Pacific madrone but much more tolerant of garden conditions. It grows in sun or shade and most soils and accepts some summer irrigation as long as drainage is adequate.  Where content, it can reach fifteen to thirty feet tall and almost as wide.

Cultivated varieties of Arbutus unedo are common in the nursery trade. ‘Elfin King’ is a compact shrub with denser branching and somewhat slower growth than the species. ‘Compacta’ is said to be similar, reaching six to ten feet tall and wide at maturity.

Arbutus ‘Marina’ is a fairly large tree (forty feet tall and thirty feet wide at maturity) that looks enticingly small in fifteen-gallon containers.  You will see it planted five feet from a building wall in new landscapes.  In such situations you can be sure it will outgrow its allotted space and over time will require quite brutal pruning or removal.

‘Marina’ is often promoted as a garden-tolerant equivalent of Arbutus menziesii, and it is somewhat more accepting of typical garden conditions – a bit of summer water, less than perfect drainage, and clay soils.  But it won’t take as much abuse as commonly assumed, especially excess irrigation or poorly drained soil.  It is also best planted in a spot that can feature rather than fight the shedding of bark, fruits, and large leaves, which, as with most strawberry trees, is pretty much continuous.

Toyon

Toyon (Heteromeles), California native evergreen shrub, with Verbena by entry to side garden Sibley drought tolerant front yard garden, Richmond California

Toyon (Heteromeles arbutifolia)

If you have space in your garden for a large shrub or small multi-trunked tree that will live for decades, is attractive year-round, and provides food and shelter for wildlife, you can hardly beat California’s native toyon (Heteromeles arbutifolia) for its resilience, habitat value, and natural beauty.

Toyon is native to much of California and survives drought, though occasional deep watering may be needed in the driest times and will bring fresh new growth with quick results.  Toyon needs good drainage and thrives in full sun to part shade but tolerates full shade.

Heteromeles arbutifolia (Toyon, Christmas Berry) berries

Toyon winter berries

This ten- to fifteen-foot tall by eight- to ten-foot wide evergreen shrub makes a fine screen or specimen plant, handsome at all times of year. The clusters of tiny white summer flowers are attractive to butterflies, and birds love the bright red wintertime berries.  Deer will browse the new leaves and may strip leaves up as high as they can reach.

Toyon is commonly damaged by fungal leaf diseases, often as a result of poor air circulation.  Plants sprout vigorously after cutting back, which produces dense new foliage that is gratifying to the gardener but ultimately may subject the plant to foliar disease.  New plants should be spaced at least 8 to 10 feet apart, not crowded by other plants, and never sheared as a hedge or cut back hard without vigilant follow-up to ensure that new growth is not too dense for good air circulation.

Give toyons plenty of space, prune lightly to shape, plant on mounds or slopes for good drainage and you will have one of the most rewarding evergreen shrubs that California has to offer.

Armeria

California native plant garden with Armeria maritima and Pacific Coast hybrid Irises groundcover lawn substitute.

California native plant garden with Armeria maritima edging a walkway

Sea pink or sea thrift (Armeria maritima) was once more commonly found on “drought-tolerant” plant lists than it is today.  Gardeners who were led to plant it no doubt discovered that it just doesn’t thrive without summer water or afternoon shade except right along the coast.

Sea pink is nonetheless perfect for small gardens or small garden areas where a little summer water can be spared.  Its densely hummocky cushions of evergreen grassy leaves are six inches tall and spread to about a foot wide.  Pink or sometimes white flowers cover the plant from late spring to early summer.

Armeria maritima (Thrift, Sea Pink)

Armeria maritima

Native to coastal areas of northern Europe and the Mediterranean, sea pink is also found in western North and South America.  It prefers good drainage and grows well in sandy or rocky soils as well as in clay.  Use it in rock gardens, in fast-draining containers, or between paving stones in close-up areas where you want a colorful accent.  It is best in part shade inland, full sun along the coast.  The subspecies californica is native to central and north coastal California and is present but uncommon along the south coast.

California buckeye

Aesculus californica, California buckeye tree in winter with bare branches at East Bay Regional Parks Botanic Garden, Berkeley.

Aesculus californica, in winter, at East Bay Regional Parks Botanic Garden, Berkeley.

California buckeye (Aesculus californica) puts on a bold and fascinating seasonal show.

In late winter bright apple-green new leaves burst forth at branch ends and rapidly unfold, quite suddenly claiming the stage among the darker greens of evergreen oaks, bays, and pines.  In spring to early summer showy spikelike clusters of lightly fragrant creamy white flowers are held gracefully upright above the leaves.  The large polished-brown seeds peeking through leathery, pear-shaped pods are highly decorative on silvery gray branches in fall.

Flower head of Aesculus californica - California buckeye tree

Aesculus californica flowers

Native to much of California on dry slopes, in canyons, and along waterways, California buckeye needs no summer irrigation once established, though trees will respond to heat and drought by dropping leaves.  It’s hard to be fully prepared for the large palmate leaves to turn pale yellow, droop sadly on the tree, and drop in what seems to be high summer.  Occasional deep soakings may help keep leaves on the tree a little longer in coastal areas.

California buckeye grows 15 to 35 feet tall and spreads more widely.  Form is best in sun, where trees develop into a living sculpture of multiple or low-branching trunks, symmetrically outstretched branches, and a delicate tracery of small branchlets.  Trees thrive in part shade but may be awkwardly shaped and rangy. Good drainage is appreciated.  Deer will browse the leaves.

Aesculus californica-California Buckeye in fall fruit

Aesculus californica fruit

In years of normal rainfall, the heavy seeds sprout and establish themselves pretty much where they fall, unless they roll downhill or are carried away by water.  They can be moved before the large whitish root finds its way into the soil.  Plant with the root covered by soil and the seed at least partially exposed.  Keep soil lightly moist until new growth is decisively underway.  Water for the first year or two, especially if winters are dry.

Achilleas

Achillea 'Moonshine' (Yarrow) Yellow flowering in perennial border

Achillea ‘Moonshine’

Achillea millefolium is a variable perennial, with one kind or another found throughout temperate regions of North America, Europe, Asia.

California has several native kinds of A. millefolium, but the most widely available and commonly planted achilleas, such as the canary yellow ‘Moonshine’ or golden yellow ‘Coronation Gold’, are named hybrids or selections of other species or of plants originating elsewhere.  You may have to seek out the lovely long-lived white- to pink-flowered native achilleas at native plant sales or nurseries that specialize in California natives.

Achillea millefolium 'Island Pink' (Yarrow) in meadow garden

Achillea millefolium ‘Island Pink’, a selected form from the Channel Islands off the coast of California

Achilleas have lacy, finely divided, aromatic, green to gray-green leaves and small daisy-like flowers in compact flat-topped clusters.  Grown in full sun, plants form dense mats six inches to a foot or so tall with masses of flowers on stalks a foot to three feet tall, showy for months in late spring through summer. Blooming can be prolonged into fall by removing spent flowers before they go to seed.

Easy, vigorous, and adaptable, achilleas spread by underground rhizomes, less so by seed, and may be considered invasive in orderly gardens.  Dig deeply, divide, and replant if clumps begin to spread beyond where you want them to grow.  Plants are better behaved with restricted summer watering, though occasional water will improve their appearance in inland areas.

Achilleas make a fine accent or harmonizer and are especially effective in meadow gardens with mounding or spiky grasses or mixed with other perennials. Named cultivars of Achillea millefolium come in a wide range of colors that change subtly with age. Mid-season flowers feature a pleasing combination of varying shades of white, pink, salmon, lilac, orange, crimson, or purplish red, turning buff-colored and then tawny brown as seeds mature.

Flowers are irresistible to butterflies and attractive in both fresh and dried arrangements.  Birds feed on the foliage in winter.  Seemingly undeterred by the rather strong fragrance of the leaves, deer often browse the flowers.

Irises

Pacific Coast Iris 'Copper' flowering in garden with Euphorbia dulcus 'Chameleon'

Pacific Coast iris ‘Copper’ flowering in garden with Euphorbia dulcis ‘Chameleon’

Plants that are dormant or not actively growing during the hottest months are well adapted to summer-dry climates, including many California natives.  Irises, both native and not, are a beautiful choice.

Pacific Coast Iris douglasiana (Douglas Iris) hybrid; California native plant in flower

Iris douglasiana hybrid

Douglas iris (Iris douglasiana) forms an upright clump of sword-shaped or grasslike green leaves, mounding and spreading with age by underground rhizomes.  Flowers are blue-violet, deep purple, or occasionally white, often two or three on each upright stem in late winter to mid-spring.  Native to coastal California and Oregon, this Pacific Coast iris happily tolerates summer dryness in sun near the coast or inland in part shade.  Most leaves will die back in summer but return with fall rains.  Deer ignore this plant and its many named varieties.

One of the most garden-tolerant and easily grown named Pacific Coast irises is ‘Canyon Snow’, with bright white flowers with golden yellow markings at the base of each petal.  Wide-spreading clumps of glossy green leaves are covered with flowers on foot-tall stems in early spring.  Plant in late fall, when new growth starts, usually after the first rains.  Good to excellent drainage is essential; best massed on hillsides or planted on earth mounds or in raised beds.

Pacific Coast iris 'Canyon Snow' and Erigeron

Pacific Coast iris ‘Canyon Snow’ with Erigeron

Bearded irises are another great choice for summer-dry climates, though they are not native to California.  They do benefit from dividing occasionally, at least every four or five years, but they thrive with little or no supplemental watering, even during droughts.  They may not bloom as heavily without winter rains, but they return with vigor when the drought subsides.

Bearded irises are particularly long lived. A small group of old-fashioned yellow-flowered plants have persisted in my garden since I arrived, thirty-five years ago, without dividing and with no supplemental water.  Another bearded iris, with deep purple flowers, I found here the same year, distributed randomly all over the property.  I have gathered them together in one eye-popping display, dividing occasionally but otherwise providing no water and no care.