The Dry Herb Garden

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The varied shapes and textures of society garlic, salvias, artemisias, and German statice intermingle for a pleasing dryland garden scene.
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The spiny blue sea holly pairs with ‘Valerie Finnis’ artemisia in the authors’ hell strip, that tough area between the sidewalk and street.
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Yarrow, flax, and sea holly: beautiful and drought tolerant.
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Coyote mint and yellow penstemon are found in many gardens in the West.

From a window seat on a New York to Los Angeles flight, one can watch the colors of the land change. As you fly across the Great Plains, lush green forests and fields give way to paler shades of green and tawny gold, and finally to muted tones of sage, gray, buff, and beige.

The western landscape, with its extraordinary geographic features, often bakes under a rainless sky. Its plant life, however, is supremely adapted to the mineral-rich but humus-poor soil, dry air, summer heat, and winter cold. Transplanting an East Coast herb garden vision to the West takes water–an increasingly precious commodity, which limits the plants that can be grown well. But many stalwart herbs and ornamental perennials revel in the heat and drought or at least adapt well to these conditions.

Western gardens can draw from a broad palette of plants that reflect the colors of the native landscape–shimmering silver, dusty blue, sage green, russet brown, and sun-bleached yellow. Dryland herbs need not be planted in Death Valley fashion, with yards of gravel between each plant (and a wagon wheel or steer skull for emphasis). An herb garden that receives little or no supplemental irrigation can be a thing of beauty–full and lavish, teeming with texture, color, scent, and variety.

Dryland gardeners have learned to incorporate compatible herbs that echo the beauty of the natural surroundings. Some are native while others originate in lands with similar climates, such as the Mediterranean region, Central Asia, the Middle East, Eastern Europe, South Africa, and the west coast of South America.

The need for water-wise plantings is not limited to the arid lands of the West. An estimated 50 percent of a homeowner’s water goes toward landscape maintenance. Within the past decade, many parts of the country have experienced prolonged droughts and water restrictions.

The goal of a water-wise garden isn’t no-water plantings. All dryland plant­ings need to be watered the first year, but once they are established, many herbs will thrive on only 2 inches of water each month, and some require only half that much. Let us walk you through our garden in Denver, Colorado, and point out some of our favorite dryland herbs and flowers.

First impressions: Hell strips 

One of the most difficult areas to maintain in any garden is that narrow patch of lawn between the sidewalk and the street known in our part of the country as a hell strip. Trapped between a river of asphalt and a stream of concrete, the grass easily bakes to a crisp in hot weather. Most grasses go dormant during extended periods of drought and heat; only by keeping them on the life support of water do they come through. Dead and dying grass is an open invitation for opportunistic weeds to get a foothold. There’s really only one solution: get rid of the turf. If any part of the home garden was meant for water-wise planting, this is it.

The scorching summer sun may be inhospitable to bluegrass, but a wonderful array of herbs can withstand the tough conditions in hell strips. Any number of forms of Dianthus make a splendid show when they blossom in early summer. After we cut back the faded flowers, the gray or green needlelike foliage is handsome until the snow flies. To edge the walk, we’re espe­­cially fond of diminutive ‘Tiny Rubies’, whose bright pink flowers the size of a dime rise about 4 inches above a tight mat of gray-green leaves. Other pinks that thrive and self-seed in this environment include cottage pink (D. plumarius) and maiden pink (D. deltoides).

Artemisia schmidtiana ‘Silver Mound’ performs admirably on this austere regimen and never opens up in the middle as it often does with more water and richer soil. Partridge feather, Greek yarrow, thymes, ice plant (Delosperma sp.), sunroses, dwarf bearded iris, tunic flower (Petrorhagia saxifraga), and Mount Atlas daisy (Anacyclus pyrethrum var. depressus) also stay compact and healthy. Self-sowing annuals take care of themselves. California poppies in pastel tones of pink and cream contrast with the vivid desert bluebell (Phacelia campanularia). It’s an international mélange of plants, made possible precisely because the dry conditions approximate the plants’ homeland conditions. Losses are minimal in winter, even for South African ice plants, because the roots don’t rot in waterlogged soil.

City regulations often dictate that plants in the hell strip other than the trees not exceed a foot in height, but we’ve never had any trouble when we leave the flower stalks of lamb’s-ears, snow daisy, and purple-blue Rocky Mountain penstemon (Penstemon strictus).

Our native prickly poppy (Argemone platyceras) is right at home in the sun-baked hell strip. Prickly poppy is sometimes called cowboy’s fried eggs because of its white petals encircling a yolk-yellow center. In several low-water areas of our garden, it appeared of its own accord, but it’s a welcome addition. The glaucous foliage and tissue-paper-thin petals of the large, pure white blossoms elicit comments from even sophisticated gardeners. More than just a pretty face, prickly poppy has a long tradition in the West among native peoples as a healing plant.

Other western native herbs, such as blue prairie flax (Linum perenne subsp. lewisii), Indian blanket (Gaillardia aristata), hummingbird’s trumpet (Epilobium canum subsp. latifolium), and Missouri evening primrose (Oenothera macrocarpa) also do well in the hell strip. We put purple coneflowers (Echinacea spp.) in a low spot where runoff tends to collect.

By replacing turf with herbs and flowers, we became pioneers in our neighborhood, but the concept has been catching on from coast to coast. In some communities, particularly in California, there is already a strong ­tradition of pretty, drought-tolerant front gardens.

High impact

Our border gardens are planted so that the beds are gradually more drought tolerant the farther we get from the house (and the faucet). Many plants that originated in arid and semi-arid regions have small, fine-textured hairy or gray leaves that cut down on water loss, resist heat and wind, and reflect light rather than absorbing it. Although they are visually interesting, a border made up solely of fine texture needs help, which comes in the form of bold plants with outstanding architectural qualities.

These high-impact herbs include sea kale (Crambe maritima), whose thick, waxy leaves look like lovely turquoise blue cabbage. They unfurl quickly and dramatically in spring as stout stems more than a foot high produce clusters of creamy white blossoms. The inflated pods that follow are equally showy. The roots of sea kale can be dug and eaten, as Europeans have done for centuries.

The smooth, slightly wavy leaves of horned poppy (Glaucium flavum) also have a turquoise sheen. In early summer, they complement the crinkled, amber yellow flowers that are followed by long seedpods curving like the fingernails of an ancient Chinese concubine. The pods impart an unusual textural element to the garden or dried arrangements. Left to set seed, the plants usually behave as biennials or short-lived perennials.

The beautiful foliage rosettes of some mulleins are reason enough to grow them, but their flowering spikes make them indispensable in the dry border. Verbascum bombyciferum displays silver-gray leaves covered with a white cottony down that catches the sun and highlights its luminosity. The soft, sage green leaves of miner’s-candle (V. thapsus) also have a feltlike texture. V. widemannianum displays a rosette of olive green leaves in its first season.

Most mulleins are biennial, sending up a flower stalk in their second year. Mullein spikes are to the dryland gardener what delphiniums and monkshoods are to the gardener in a moist climate. They add both height and drama to the border. Most mulleins open their blossoms only on sunny mornings and close them by noon.

Scotch thistle (Onopordum acanthium) is the king of architectural plants for the water-wise garden, or any other one for that matter. It’s 6 to 8 feet tall (even taller with more moisture), and its spiny arms and purple thistle flowers scare the neighbors to pieces. Perhaps they fear a giant mutant strain of dreaded Russian thistle has invaded. Their concerns about an invasion in their yard are largely unjustified, as the seeds of this biennial plant are relatively heavy and fall close to the mother plant rather than floating on the breeze. We do take care to deadhead our Scotch thistle (except for a single flower head to ensure a handful of new plants) because it seeds like mad and could get out of hand.

The felty, scalloped leaves can grow to 2 feet or longer, and an entire plant may occupy a spot 5 feet in diameter. There’s a sharp spine between scallops on the leaves, and the stalk is also armed and dangerous, making it a bear to remove if you change your mind about it at midseason.

The tiered spikes of Jerusalem sage (Phlomis fruticosa) are another splendid structural addition. In frost-free areas, Jerusalem sage grows to 6 feet or taller with an equal spread, blooming in spring and into summer with whorls of yellow tubular flowers. Its herbaceous perennial cousins include straw yellow P. russeliana and peculiar buff-and-olive P. samia, both hardy at least to Zone 5 and very drought tolerant, and three “pretty in pink” species, P. alpina, P. tuberosa, and P. cashmeriana. The pink-flowered species make desirable border plants, but none is noted for drought resistance, and P. cashmeriana actually prefers partial shade. Expect spikes 3 to 4 feet tall from all of these peren­nial Phlomis with the characteristic stacked whorls that stay ornamental even after the flowers fade.

Planning a planting

When planning a dryland plant­ing in the hell strip or some other dry spot in the yard, don’t underestimate the staying power of grass. It has an uncanny ability to go dormant in hot, dry weather and survive until growing conditions improve. If you want to convert that strip of lawn along the street into a flower bed, be sure that the grass is truly dead. There are myriad ways to kill a lawn, and we’ve tried most of them: chemical attacks, suffocation by plastic or newspapers, and cruel and premeditated neglect. The last is seldom effective.

We believe the best way to be sure that the grass is gone is to strip off the sod and take it to the compost pile. This is the most labor-intensive method of turficide, but it’s worth it in the long run. Stripping off the sod allows you to level the bed at or below the level of the curb to conserve natural rainfall.

Second, till the soil. You need to overcome years of compaction. Start with a good shovel or spading fork, and work the ground. This is the time to add any soil amendments that you want. Remember, many dryland plants are adapted to poor soils and resent too rich a mixture. Most soils, whether sandy loam or heavy clay, need only a thin layer of compost. A small amount of compost or other organic matter will lower the pH ever so slightly in an alkaline soil, and a dusting of lime can sweeten an acid soil. The addition of organic matter loosens clay soil so that water can percolate downward, and it helps to hold moisture in a sandy soil. Organic matter also helps hold nutrients and make them available to the plant.

After you’ve selected and planted your dryland herbs and flowers, water them well. Continue to water regularly during this first growing season to ensure that they become well established.

Blossoms for dusty places

The list of perennial herbs for a low-water border is a long and lovely one. For height and invigorating aroma, Russian sage (Perovskia atriplicifolia hybrid) and agastaches make compelling focal points. The flowers of Russian sage are lavender whereas Agastache barberi covers its upright stems in bright, mauve-pink tubular flowers. The flowers of A. cana are bright pink whereas those of A. rupestris are apricot. The fluffy lavender flower heads of anise hyssop (A. foeniculum) make pretty border accents and hold well into winter as they bleach to straw gold.

Lavender-blue meadow clary (Salvia pratensis) and clary sage (S. sclarea) get by with little supplemental moisture. Their flowers contribute to the full, lush look that belies the scant moisture a dryland border actually receives. Some gardeners prefer the deep blush of ‘Turkestanica’ clary, but the paler species has its charms as well.

Grecian foxglove (Digitalis lanata) takes to heat and drought the way D. purpurea takes to shade and water. Grecian foxglove has gray-green woolly leaves and a rigid stalk of whitish flowers with a delicate tracery of brown veins and a pale orange throat. Once established, it reseeds reliably. The upright 3-foot spikes of purple toadflax (Linaria purpurea) and the pale pink cultivar ‘Canon J. Went’ contribute a sprightly, more delicate look that is equally appealing. The bold lavender-purple spikes of spike gayfeather (Liatris spicata) and western snakeroot (L. punctata) are the brightest exclamation marks of all in the dryland border.

Predominantly fine-textured perennial herbs effortlessly endow the dryland garden with the billowing look that English border makers strive so hard to achieve. It’s easy to incorporate airy lavender German statice (Goniolimon tataricum) and willowy, long-blooming apple-blossom grass (Gaura lindheimeri). Artemisias, common oregano, and garden sage form graceful, flowing mounds that tie perfectly into interlocking clumps of thyme, ballotas, marrubiums, pinks, and thrift. Spikes of many species of Penstemon, vivid orange butterfly weed (Asclepias tuberosa), and bearded iris rise from the rounded forms and draw all eyes in early or midsummer. Grown lean and mean, the iris is rarely bothered by borers or rot. The same regimen also prolongs the life of many other perennials that would otherwise expire quickly after a few years of lush living.

Spreading, rambling herbs weave through the dry border. The round flower heads of prairie snowball (Abronia fragrans) exude a piercing sweetness in late afternoon. Rock soapwort (Saponaria ocymoides) smothers itself in vibrant pink flowers (and a pretty white form has just been introduced) in early summer, and kidney vetch (Anthyllis vulneraria) responds with clusters of bright yellow blossoms.

Bulbous herbs that tolerate periodic dry spells include white garlic chives (Allium tuberosum), blue garlic (A. caeruleum), chives, Turkish onion (A. karataviense), and garlic. On the West Coast, society garlic (Tulbaghia violacea) from South Africa thrives on neglect, forming large clumps of foot-tall grassy leaves topped by lavender-mauve blossoms. Saffron crocus (Crocus sativus) likes it really hot and dry. Planting this Middle Eastern native in a rich, moist soil is a death sentence.

Annuals for dryland gardening fall into the “no muss, no fuss” category. A bit of judicious thinning will keep their numbers manageable in the first few years of a new garden, but as the perennials expand, annuals must find a way to fit in, and they usually do. When introducing a new annual, we often loosen the soil surface in autumn, scatter the seed, and lightly tamp the soil. Many annuals sprout during winter and early spring. Once established, they retain at least a foothold. Besides the western gardener’s best friend, California poppy, our annual favorites include golden yellow blazing star (Mentzelia lindleyi), night-blooming angel’s-trumpet (Datura innoxia), borage, opium poppy, dill, larkspur, sunflower, bachelor’s-button, and love-in-a-mist. To a lesser extent, summer savory, amaranths, safflower (Carthamus tinctorius), wallflower, dyer’s coreopsis (Coreopsis tinctoria), and nasturtiums also cope well with limited irrigation.

Rue, purple coneflower, catmints, hyssop (Hyssopus officinalis), wall germander (Teucrium chamaedrys), Jupiter’s-beard, and rose campion all do well in borders that ordinarily receive plentiful rainfall, but they can also endure periodic dry spells.

Mediterranean influence

Among Mediterranean shrubs, West Coast gardeners have long used lavenders, santolinas, curry plant (Helichrysum italicum), and rosemary (Rosmarinus officinalis). Northerners envy these gardeners for their ability to grow rosemaries, with their haze of blue or occasionally white or pink flowers cloaking the strongly structured branches. The hardiest of the lot is ‘Arp’, an open, upright cultivar with lavender flowers and lemon-scented gray-green leaves. Named for the Texas town where it was found, ‘Arp’ is hardy to ¯10°F, or Zone 6.

Other upright varieties of rosemary include the pink-flowered ‘Pinkie’, ‘Majorca Pink’, and ‘Roseus’; the white ‘Albus’, as well as dark blue ‘Tuscan Blue’, pale blue ‘Miss Jessop’s Upright’, and free-flowering ‘Sissinghurst Blue’. Prostrate types that spill over walls or tumble down slopes include violet-blue ‘Severn Sea’, dark blue ‘Fota Blue’, and sky-blue ‘McConnell’s Blue’. All of these cultivars also demonstrate differences in the color, shape, and taste of their leaves as well as growth habits.

Bay (Laurus nobilis) makes a strong presence in many West Coast gardens; clipped topiary specimens can emphasize formality. California bay (Umbellularia californica) has attractive clusters of yellow flowers in spring and leaves that resemble those of culinary bay. When crushed, they release aromatic oils that smell like a cross between witch hazel and camphor; they should not be used in cooking.

This article is adapted from Herbs in the Garden, by Rob Proctor and David Macke, available this fall from Interweave Press. Rob is a regular contributor to The Herb Companion.

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