Workhorse Ground Covers Save Time, Money (and Water)

Creeping thyme

Fragrant creeping thyme blooms in summer

Much as I love putzing around in the garden, these days I am drawn to plants that do most of the work for me (and as an added benefit, save money). Drought-tolerant groundcovers that thrive in our foothills climate and soil offer a goldmine of low-maintenance, attractive landscaping options with many benefits. They need far less water than many ornamentals. They often require little or no fertilizer or products to battle diseases and pests. Many spread quickly, so gardeners don’t have to break the bank to get great swaths of them. They help stop erosion. They act as a mulch to cool the soil and conserve moisture. And my personal favorite, they crowd out weeds.

California native ceanothus in full spring bloom

California native ceanothus in full spring bloom

One thing to keep in mind even with drought-tolerant groundcovers is that like any young plants in your landscape, they need more water the first year or two in order to develop a strong root system to survive periods of drought. Given our tough water restrictions this summer, consider planting these or other water-wise groundcovers in early fall, when the water you give them will soon be followed by the cooler, wetter seasons.

Following are either western native or drought-tolerant groundcovers that make light work of routine gardening. Most are three to 12 inches tall. The list is loosely organized by virtue: green year-round, flower power, foot-friendly, and those made for the shade.

Two varieties of sedum complement each other

Evergreens   Common but lovely are low-growing varieties of our native California lilac (Ceanothus) with smoky purple flowers in spring the bees love, and bearberry or creeping manzanita (Arctostaphylos uva-ursi) with tiny, bell-shaped pink flowers and red fruit. Less common, low-growing wall germander (Teucrium chamaedrys) sports small, glossy, dark green leaves and teensy lilac flowers. There is a mind-boggling selection of succulent sedums, many of which flower in late summer or fall. Dwarf coyote brush (Baccharis pilularis) is one of the fastest-growing, toughest groundcovers around. Ground-hugging juniper and prostrate rosemary also offer hardy year-round green.

Gazinias offer a riot of color

Easy to grow gazinias offer a riot of color

Dazzling Flowers   With all due respect to the flowering groundcovers mentioned above, there is nothing like the car-stopping appeal of these plants in spring and summer: pink-flowering creeping thyme; snow-in-summer (Cerastium) with its carpet of white flowers; the daisy-like gazinias (pink, orange, white, red, purple); and trailing verbena, in as many colors. Also consider southwestern native Sierra sundrop (Calylophus hartwegii), which produces neon yellow, cup-shaped flowers on dark green, trailing foliage.

Foot-Traffic Friendly   A few drought-tolerant groundcovers will withstand some foot traffic, which is an added benefit in the garden. Native common yarrow (achillea), with its feathery foliage and white to pale yellow flower caps, as well as fragrant chamomile, can be mowed periodically and used as lawn substitutes. Most thymes take light foot traffic, as do some of the small-leaved, mat-forming sedums.

Sweet Woodruff loves shade

Sweet Woodruff loves shade

Shade-tolerant Grapeholly (mahonia) does just fine, thank you, in dry shade. It is an evergreen that has yellow flowers in spring and purple berries in late summer. Hummingbird sage (salvia spathacea), also an evergreen, produces spikes of pink to purple flowers. Sweet woodruff (Galium oderatum), with its star-shaped whorls of leaves and lacy white flowers, is actually an edible herb said to taste a little like vanilla and smell like freshly mown hay when the leaves are crushed. During times of drought, it does better in higher, cooler, woodland settings.

Sun loving artemesia adds a soft, silvery accent

Here are some resources for doing your own research on groundcovers:

University of California’s “The California Garden Web” at

The local chapter of the California Native Plant Society at

The Tuolumne County Master Gardener hotline, 209-533-5912; or complete the “Ask a Master Gardener” form at

Rachel Oppedahl is a UCCE Tuolumne County Master Gardener who has little patience with fussy, thirsty, pestand disease-prone gardens.




Buffalo Grass a Better Lawn Alternative

A more drought friendly buffalo grass lawn.

A more drought friendly buffalo grass lawn.

If you’ve ever toyed with the idea of replacing your lawn with something less thirsty (and less work), this is the year to do it. Because of the severity of the current drought, Tuolumne Utilities District has placed a total ban on watering lawns; so water-hungry grasses will likely die this year in our typically long, hot, dry summer.

What are the alternatives? You could lose the lawn entirely with some combination of hardscape and drought-tolerant groundcovers—and there are many of the latter. But if you have your heart set on something resembling a lawn, something kids and pets can play on, consider buffalo grass.

Native to the American prairies (yes, where the buffalo roam), several varieties of this low-maintenance grass have been studied by universities, including UC Davis, for their usefulness in other parts of the country. Turns out, there are a lot of reasons to choose buffalo grass for California landscapes:

• Because of its deep root system (6- to 8-ft deep), buffalo grass requires about 1/4-inch of water per week, which is about 75 percent less than traditional lawns.
• Most varieties have a natural, broad insect and disease resistance.
• It requires little fertilizer and, compared to traditional lawns, infrequent mowing.
• The top-rated buffalo grasses for our area (see below) are nearly pollen free, so they are excellent choices for people with grass allergies.

The Tuolumne County Master Gardeners started experimenting in 2008 with buffalo grass in its demonstration garden near Casina High School, on Barretta Street in downtown Sonora. One variety, “Prestige,” has been a clear winner for appearance and hardiness in the demo garden, but the UC Davis-developed “UC Verde” comes in a close second. Prestige, released for commercial cultivation in 2004 by the University of Nebraska, produces a soft, dense grass of medium-green color with fine blades. In most locations, it grows four to six inches tall, spreads quickly, and is aggressive enough to choke out most weeds. Prestige is recommended for elevations above 1,200 ft and as high as 6,000 ft. UC Verde has the same qualities as Prestige but can reach a height of eight inches. It is recommended for elevations below 1,200 ft. Both varieties require full sun for at least six hours a day.

Both Prestige and UC Verde turn brown in winter, but reliably return to put on a show of green in spring. If you cannot tolerate a brown lawn even in winter, you can actually buy a turf colorant to keep it looking vibrant. You can create a buffalo grass lawn with seed, sod or plugs, the latter being the most popular method. Normally the best time to plant buffalo grass is from April 1 to October 1. But since even drought-tolerant grasses need a little more water when first planted to get established, early fall would be the best time to plant buffalo grass in the foothills this year.

To learn about the UC Davis test site for UC Verde, visit:

To see photos of Prestige and UC Verde lawns and to order plugs, visit:, is a Nebraska-based grower from whom the Tuolumne County Master Gardeners purchased Prestige. This website also offers a tool to calculate how many plugs you will need to cover the size of your new lawn., a firm based in San Clemente, California, is very informative and has great photos of UC Verde lawns., is the buffalo grass-specific website for another California-based grower, Takao Nursery in Fresno.

If you would like to see the small plots of buffalo grass in the Master Gardener Demonstration Garden, you can visit during Open Garden Day on the first Saturday of each month, from 10am to 1pm.

Rachel Oppedahl is a UCCE Tuolumne County Master Gardener.  This article first appeared in the Union Democrat.

Understanding Plant Life Cycles Can Be Tricky

One of the most daunting things about garden design is understanding how, and for how long, plants will likely thrive and reproduce (or not) in your yard.  The gardening terms can seem confusing or vague:  annual, perennial, self-sowing, hardy, tender, etc.  But understanding these terms can go a long way in helping you develop a landscaping plan that succeeds.



To start, the terms annual, biennial and perennial refer to a plant’s natural life cycle, and to a lesser degree, how reliably it will appear year after year in your garden.

Annuals complete their life cycle in one year or growing season.  They sprout, leaf out, flower, set seed; and then the entire plant, down to the roots, dies.  The only thing that ensures the plant’s continuance from one generation to the next is the seed it drops after flowering.  Examples of popular annuals include poppies, zinnias, marigolds and most vegetables.



Biennials have a two-year life cycle, in which they develop foliage the first year and produce flowers the next, then set seed and die (or die back to a bulb). These plants typically require a cold dormant period after the first year in order to develop flowers the second.  Common examples include foxglove, pansies, hollyhocks and vegetables such as cabbage.

Perennials are plants that live for more than two years.  The aboveground plant may die back to the ground in its dormant season (typically winter), but it reemerges from its root system or bulb the following year.  Peonies, coneflowers, yarrow and bleeding heart are examples of popular perennials.  While a perennial reemerges and spreads from the original plant from its root system, it might also set seed and create a new, separate plant.  Certain Black-Eyed Susan varieties do this.



What can be confusing for home gardeners is that the above definitions often only apply when the plant is given its natural or ideal growing conditions.  True perennials in mild winter or tropical climates might not survive the first winter in, say, the Sierra foothills.  For example, perennials such as geranium, lantana and impatiens should be thought of as annuals here, as they will likely be killed by the first hard frost. Put those same plants in a more tropical climate, and they do in fact behave as perennials, returning the following year.

There are a few other common points of confusion when it comes to the life cycles of garden plants.  First, the term “perennial” does not mean forever.  There are short- and long-lived perennials.  Some, such as columbine and Shasta daisy, typically will live only several years before they start to fade and die, while stalwarts such as peonies, day lilies and lilacs can live for decades.

Morning Glory

Morning Glory

Just because a plant is said to “self-sow” (reproduce itself by dropping seeds), that doesn’t mean you can bank on it creating new plants every year.  Some self-sowers, such as columbine, gloriosa daisy and spider flower, are reliably successful at yielding new plants from seed, but others, such as morning glory and moonflower, with their hard seed coats, can be iffy unless you intervene by soaking and scarring them.  Plus, the conditions under which seeds will actually germinate have to be just right; and even then, birds might eat them before they have a chance to sprout.

The terms “hardy” and “tender,” while not part of a plant’s life cycle per se, are important in this context, especially relating to perennials.  These terms refer to a plant’s ability to withstand cold temperatures.  Those that tolerate some amount of short-term freezing are cool-season or “hardy,” whereas those that are killed or injured by freezing temperatures are warm season or “tender.”  The growing “zone” designations on nursery plant tags and in gardening books are guides to a plant’s winter hardiness by area.

To design a garden that will bring you the most pleasure, consider each plant’s life cycle, lifespan and hardiness for your climate.

Rachel Oppedahl is a UCCE Tuolumne County Master Gardener.  This article first appeared in the Union Democrat.

Learning to Love a Winter Garden


Yarrow seed head

On my drive to work each morning, I pass a stand of three-foot-tall yarrow, a nearly indestructible perennial with long-blooming, flat-topped yellow flower clusters and feathery foliage.  For months now, the flower heads, leaves and stalks have been brown and withered.  “Dead, ” as some might say.  But I love them, and am grateful to the homeowners who leave them on display.  Birds relish the dried seed heads when other garden pickings are slim; and to my eye, there is a certain beauty in the structure and muted colors of many hardy perennials, including yarrow, in fall and winter.

So, I have mostly chucked the gardening aesthetic that says anything that looks dead should be immediately whacked to the ground or pulled up.  While there are some perennials that should be cut back in fall (more about that later), many are better left standing until spring.  Here are some reasons why:

Winter beauty

Food for the birds.  Some of the loveliest yet toughest flowering perennials, such as coneflower, globe thistle and black-eyed Susan, offer dried seed heads birds love.  Native vines like pink honeysuckle and Virginia creeper produce, respectively, red and dark blue berries in fall that help birds fatten up for winter.  The American beautyberry bush has gorgeous rosy-purple berries that hang in clusters well into snow season.

Winter protection for the plant.  The dried flowers, seed heads, leaves and even stalks collect snow and other loose leaves that help insulate the plant’s crown, thereby increasing its chances of surviving the winter.  This is especially true of some marginally hardy perennials, like garden mums.  Another aspect of winter protection is the fact that, generally speaking, cutting back often stimulates new, tender growth that definitely cannot withstand our winters; and this dieback can sometimes endanger the whole plant.

Shelter for wildlife.  Many butterflies overwinter in plant “debris,” and even birds can take cover under substantial overwintering perennials.

A flag for you.  Ever forget where you planted a prized perennial the previous spring?  If you leave the plant standing through winter, come spring you’ll have a reminder.  The other benefit of leaving the dormant plant as a marker is that you won’t inadvertently dig up a beloved perennial in a spring planting craze.

Sedum Frosty3Sm

Autumn Joy Sedum

While many hardy perennials are indifferent to the issue of cutting back  — they will survive either way  — there are definitely some plants that prefer not to be cut back in fall.  A few examples of popular perennials that appreciate being left alone until spring  are artemisia, asters, butterfly bush, campanula, coral bells and upright sedums.  Coral bells (heuchera), for example, have a tendency to heave in soils that freeze and thaw, so leaving foliage intact adds a protective “mulch” through winter.

All of that said, there are perennials and certain situations that call for fall cutback.  First and foremost, if a plant has diseased or insect-infested foliage, cut back and dispose of the leaves (but not in your compost pile).  Plants with blackened foliage — often a sign of fungal disease — should definitely be cut back in order to reduce the innoculum that can reinfest the plant next year.  Peonies, for example, are prone to fungal diseases such as boytritis blight in overcast, wet weather.  Removing most bearded iris foliage is a good practice, as it reduces overwintering sites for iris borer caterpillars.  And plants that are prone to mildew — think phlox, hydrangea and zinna  — are usually better off without leaves during the wet season.


Miscanthus, a lovely grass in winter, provides cover for birds

If you have to cut back a perennial in fall because of disease or its overwintering preference, or because you just can’t be talked into seeing the beautiful architecture of a dormant, snow-covered yarrow, here are a few tips for doing it right:

When:  In most cases, it is best to wait until after the first or second hard frost, when most perennials begin to go dormant, to cut back severely.

How:  Cut the entire plant back to within two to three inches of the ground — but no more.  The reason is, many perennials will form next year’s new growth at bud and shoot sites located just above the soil.  If you cut back too close to the ground, you might prevent the plant from reemerging in spring or summer.

Whether for the sake of wildlife or a new appreciation for the beauty of dormant plants, think twice about cutting back perennials in your garden.

Rachel Oppedahl is a UCCE Tuolumne County Master Gardener.  This article first appeared in the Union Democrat.

A Few Gardening Myths Dispelled

Spring and fall are actually the best times to do most garden planting, but here we are, even in triple-digit weather, still loading up our nursery carts with all of that irresistible color and scent, spending long weekends Rockroseworking on the garden of our dreams.  It’s a hard habit to break, this insistence on planting throughout our inhospitably hot, dry foothill summers — which made me think recently about other gardening habits and beliefs that we really ought to be done with, because science says, they just ain’t so.

Our foothill soil is bad for gardening because of the clay.  Having used many choice four-letter words and thrown a few shovels across the yard after hours of trying to dig planting holes up here (I am a Bay Area transplant), I won’t argue that ours is an easy soil to work with. Yes, it’s harder to dig, especially with all of the rock, and yes, too much clay in a soil can cause drainage and aeration problems with some plants. But the good news is, clay happens to be a nutrient magnet for plants.

The science of why this is so is more than most gardeners want or need to know, but it has to do with the fact that clay’s surface structure and chemical properties naturally attract many of the essential elements of plant nutrition, such as calcium, magnesium, potassium, hydrogen and iron, among others. “Because clay minerals are so active in nutrient exchanges,” explains the California Master Gardener Handbook, “they are major determinants of the chemical and physical properties of a given soil, and they largely determine how well plants will grow in that soil.”

The best way to plant is to fill the newly dug hole with soil amendments.  Recent studies show that nothing is gained by amending backfill with organic matter, fertilizer or other substances.  And some “amendment” practices can actually be harmful, like chucking a handful of fertilizer in the planting hole too close to the plant’s roots, which can chemically burn them.  Current research tells us that the best planting practice is to use the soil you just shoveled out as backfill and to use organic matter as a mulch spread over the soil after planting to improve soil structure, conserve water and discourage weeds.  This planting method will be especially successful if you dedicate much of your garden to native and/or Mediterranean plants.  If you can’t live without those heartbreakingly beautiful, fussy non-natives or want to grow vegetables, though, raised beds and amended soil are a must.

Use vitamin B1 when you plant in order to avoid transplant shock.  More recent studies have shown that vitamin B1 alone does nothing to speed rooting or prevent transplant shock.  Here’s what does work:  make sure you have picked a spot that suits the particular plant’s preferred growing conditions in terms of sun exposure and drainage; and minimize stress by planting on relatively cooler days and time of day, and not letting the plant dry out.

Fertilize landscape trees and bushes every year. While trees and shrubs less than two years old often benefit from fertilizing, research has shown that with few exceptions, mature trees and shrubs in California do not need fertilizer if they are reasonably healthy; that is, the leaves look healthy and there is new shoot growth each year.  Usually when fertilizer is needed, only nitrogen is necessary because California soils are most commonly deficient only in nitrogen.  When this is the case, the University of California’s Agricultural Extension suggests broadcasting one to three pounds of actual nitrogen per 1,000 square fee of planted area for shrubs or per six inches of trunk diameter for trees.  For newly planted trees and bushes, apply 0.2 pounds of nitrogen about three feet by three feet around the base of each plant immediately after planting, again about two months later, then once the following spring.

Speaking of spring — and again, fall  — research really does show that most new plants and seeds get a better start in life when we use those cooler, wetter seasons for planting.  It gives plant roots more time to become established before having to deal with our more stressful summers.

Rachel Oppedahl is a UCCE Tuolumne County Master Gardener.  This article first appeared in the Union Democrat.

Organic Mulches: Better Soil, Better Plants

Mulches, the soil coverings many people associate primarily with weed suppression and garden decoration, also play an important part in plant health and soil structure. The right organic mulch can enrich your garden by:

• conserving soil moisture
• moderating temperature extremes underground, thereby minimizing soil heaving, which can damage plant roots
• reducing soil erosion
• adding nutrients to the soil through decomposition of organic matter
• improving soil structure
• minimizing weeds

While the benefits of mulching for soil and plant health are clear, choosing the right mulch for your garden can be confusing because it is a game of tradeoffs. For example, wood chip mulches, which resist compaction and blowing away in the wind, have a high carbon to nitrogen ratio that might temporarily reduce nitrogen in the soil for plant uptake. Cocoa hulls are lovely, but they are expensive and can be toxic to dogs. Straw, great for a summer mulch in vegetable gardens, is highly flammable — not a desirable thing in the Sierra Foothills in August.

That said, here are some tips to help guide your decisions for mulching:

Season – Winter mulches are best for insulating woody plants (trees, bushes, perennials). Late fall, after the soil has cooled but before the first frost, is the perfect time to lay down shredded leaves, pine needles, or straw, which will help keep the soil evenly cool throughout the winter. Summer mulches, best applied in mid-spring when active root growth has started, help retain soil moisture, reduce weeds and keep soil cooler during the hottest months.

Depth – Two to four inches is the suggested depth of garden mulches.

Location – Keep mulch at least six to twelve inches away from tree and shrub trunks, and one inch away from flower/vegetable stems, to avoid rot, cankers and other diseases.

Types – Here are some of the most common mulches used:

Wood chips are readily available and are considered attractive by many gardeners. In the process of decomposing, wood chips can temporarily rob soil of nitrogen, so be sure to replenish the loss with nitrogen fertilizer or cover crops if you use them.

Bark, whether shredded or in chunks, has some of the same advantages of wood chips: it resists compaction, is easy to find, and it is attractive (especially for a more natural look). Commercial bark can, however, be toxic to young plants if it is too fresh or has been stored improperly, according to Cornell University Plantations Director and former Cooperative Extension Agent Donald Rakow. He says the best bet is to buy bagged mulch products, which “have been weathered for long periods of time to remove any toxins and are least likely to harm plants.”

Straw or hay is often used in summer vegetable gardens and strawberry patches. It is relatively inexpensive and can also be an effective winter insulating mulch. Some disadvantages of straw are that it, too, can lower nitrogen levels in soil, and it might contain grain seeds that can germinate. A thick enough layer of it can also harbor rodents.

Sawdust, which can have an acidifying effect on soil, can be beneficial to acid-loving plants such as blueberries and rhododendrons. Partly because sawdust is so fine in texture, it compacts very quickly in just one season; so, it is necessary either to fluff it up or replace it each year.

Hulls, obtained from the processing of crops such as buckwheat, cocoa and cottonseed, can add a nice visual texture to a garden bed. However, they are more expensive than traditional mulches, and can more easily be washed away by rains or blown off by strong winds.

Yard “waste,” such as leaves, pine needles and other non-diseased plant parts, is often the ideal winter or summer mulch, especially if you can chip or shred it into a finer consistency. Pine needles, the bumper crop of free mulch in our area, provides excellent protection year round, but they should be raked up and replaced annually.

Rachel Oppedahl is a UCCE Tuolumne County Master Gardener.  This article first appeared in the Union Democrat.


Gardening for Wildlife

(This article appeared in the August 30, 2012 edition of The Union Democrat.)

In a single morning recently, as I sipped coffee on the deck, several of my favorite critters came calling. An Anna’s Hummingbird drank from a nearby feeder and a red-flowering sage and then, incredibly, flew to within ten inches of my face and hovered there, looking at me, as if to thank me for my kindness (or so I imagine). One of the beautiful, noisy neighborhood Stellar’s Jays splashed and cooled herself in the simple bowl of water and pebbles I placed on the deck railing. And a butterfly danced all over my newly planted butterfly bush.

I have been thrilled — and at times, restored — by simple visitations like these. And so, I find myself drawn more and more to the idea of focusing my ever-evolving garden plans as much on creating a wildlife habitat as on designing an aesthetically pleasing landscape. They aren’t mutually exclusive, of course, but to root a garden design in drawing and caring for the wild things first is a different exercise than deciding where to put the petunias.

My inspiration these days is the simple design model offered by the National Wildlife Federation (NWF) for creating a Certified Wildlife Habitat in your own backyard. To plan such a garden, the NWF recommends you focus on providing four things: food (ideally from native plants), water, cover and places for wildlife to raise their young.

FOOD. Grow as many native plants as possible to provide the seeds, berries, nectar, foliage, nuts, fruit, sap and pollen that local wildlife thrive on. Want the thrill of hummingbirds spring through fall without having to endlessly restock that sugar-water feeder? Plant these beautiful flowering natives to attract hummers: California fuchsia, penstemon and columbine (among many others). If you would like to draw all manner of birds, try plants that produce the seeds and berries they love: lupine, California poppy (I’ve read that quail relish them), yarrow, Western serviceberry, and wild strawberries. And to help save the honeybees, consider one of their favorites, the California lilac (ceanothus), a beautiful, native evergreen bush with smoky purple flowers in spring.

WATER. If your property doesn’t have a natural creek or pond, birdbaths and well-designed water features will go a long way in helping wildlife get through our hot, dry summers. And here’s an interesting National Wildlife Federation suggestion: create puddles. “Butterflies, males in particular, can often be seen engaging in a behavior called ‘puddling,'” says naturalist David Mizejewski in the NWF book, “Attracting Birds, Butterflies and Other Backyard Wildlife.” He explains that “When they find a wet, muddy patch of soil they gather up the liquid, which is rich in minerals.”

COVER. Wildlife need places to find shelter from inclement weather and from predators. Dense bushes and trees are good, such as the California Flannel Bush, holly and mallows, as are our native conifers and oaks. Other good cover for birds and other small animals include a rock pile, a bramble patch, or a hollow log.

RAISING YOUNG. Many of the same trees, bushes, plants and landscape features that provide food and cover for birds, mammals and reptiles also serve them in rearing young. You can add to your native plantings by adding nesting boxes designed to suit wildlife, ponds for frogs, and host plants that feed the caterpillar stage of butterflies. Milkweed, for example, is the only food the caterpillar stage of Monarch butterflies will eat.

For extensive lists of native plants that draw local wildlife, contact the Tuolumne County Master Gardeners and the California Native Plant Society. Detailed guidelines and checklists for creating your own Certified Wildlife Habitat at home can be found on the National Wildlife Federation website,

Rachel Oppedahl is a UCCE Tuolumne County Master Gardener.  This article first appeared in the Union Democrat.