Five New Plants for the Drought-tolerant Garden

Breeders, growers and retailers are on the ball in 2015, coming up with plenty of new plants to add variety and year-round interest to drought-tolerant gardens. I picked five favorite introductions I recently learned about to share. They’re just the tip of the melting iceberg. There are plenty more on the way, but we’re planning on placing some of these in our garden (or already have!)

sunset western garden collection Meerlo
Sunset’s Meerlo lavender has the fragrant scent you’d expect and the variegated leaves you wouldn’t expect. If you live where winter lows dip below 18 degrees F, it’s best grown in a container or as an annual. Image courtesy of Sunset Western Garden Collection.

Meerlo lavender (Lavender allardi ‘Meerlo’ PPAF). I got to see and touch this fun new variegated lavender from the Sunset Western Garden Collection last month. Unfortunately, it’s only hardy in Sunset zones 9 and 10 (or roughly where winter lows dip no lower than 18 to 31 degrees Fahrenheit). Step up, California gardeners – this one’s perfect for your garden and herb beds. Or replace high-water hedges and grassy medians with a hedge made of several aromatic Meerlo lavenders with their evergreen foliage. Of course, you can also plant it in a container, which I might have to do. Like all lavender, it needs full sun or only partial shade and little water. It will grow to nearly 3 feet high and wide.

Luminous Pineleaf Beardtongue (Penstemon pinifolius ‘Luminous’). Any penstemon is a perfect addition to a drought-tolerant garden. You’ll be sure to enjoy hummingbirds maneuvering into the tiny flowers of the pineleaf penstemon. I have yet to see the new Luminous penstemon from High Country Gardens, but after hearing it described, I can’t wait. It’s evergreen, low growing and has bright orange flowers with yellow throats that bloom from late spring until early summer. This native perennial loves sun and looks great along the edges of rock gardens and terraced steps. The new variety grows in zones 5 through 9 and to about 8 inches tall and over a foot wide.

pinelead penstemon in rock garden
Our pineleaf penstemon grows near our other favorite drought-tolerant planting — rocks — and before our culinary sage. The new Luminous form should be a stunner.

Thin Man Indiangrass (Sorghastrum nutans Thin Man PPAF). Another great introduction from New Mexico’s own High Country Gardens, this is a selected form of a native Indiangrass. With blue, upright foliage and late summer blooms that turn bronze, this ornamental grass is selected specifically for dry, windy growing conditions faced in New Mexico and other arid regions of the Southwest. Consider it as the perfect drought-tolerant and year-round focal point for a fence or wall. It can reach heights of 6 feet and more than 2 feet in width. It’s deer resistant and hardy in zones 4 through 9.

Thin man indian grass
Thin Man Indiangrass can grow to 6 feet high. It would look gorgeous blowing in the breeze all year long before a fence or wall of your home. Image courtesy of High Country Gardens.

Brakelights Red Yucca (Hesperaloe parviflora ‘Perpa’). Maybe you like that upright form of ornamental grass, but a little more color. Then this yucca is the plant for you. I love the clever name! Yuccas send up stalks in summer with red flowers and southern California’s Monrovia says this new yucca is compact and a particularly prolific bloomer. We couldn’t wait to add the red to our garden, and planted one already. We’re holding on to another in case the first one doesn’t get established before the freeze. But it’s doing well. You can also plant several in a border for lots of red or the interest of the nearly overlapping foliage.  The yucca needs at least 6 hours of sun a day and is drought tolerant, but might bloom better with a little more moisture. It’s hardy in zones 5 through 10.

brakelights red yucca
Here’s our backup Brakelights red yucca. One is in the ground and doing great. I can’t wait to see both pop with bright red blooms.

BabyJade boxwood (Buxus microphulla var. japonica ‘Grejade’). I never really thought of boxwood as a plant for Southwestern gardens, but there was one by our north-facing front porch when we bought this house, and it’s a great evergreen shrub to welcome people to our home. In fact, the plant does surprisingly well, considering its shady, northern exposure. The new Baby Jade introduction from Garden Debut is hardy to zone 5, deer tolerant and drought tolerant. It’s also a compact shrub that reaches about 3 feet in height and width. Boxwoods grow slowly and I enjoy occasionally shaping ours. This might not be the look you want in the middle of a xeric garden, but it’s a perfect plant for entryways, foundation plantings and small patio gardens.

boxwood in new mexico
This is our boxwood, which has proved to be drought tolerant and hardy to a cooler microclimate than our zone 6B. The Baby Jade form is compact and has petite leaves.

5 Water-wise Plants that Pop with Fall Color

Fall came quickly here as our extreme climate did a number on my vegetable garden and I am mourning the loss of fresh tomatoes and cucumbers. So to pick up my mood, I’m enjoying the color that remains on many of our drought-tolerant ornamentals. Some of the native roses and wildflowers are hanging in there. Although I love fall, the time of transition is always tough for me, and it helps to have some green and lots of other color hold on longer as cool temperatures make their way into New Mexico.

woods rose in fall
On October 3, we’ve got wild cosmos and a stand of blue grama grass in the foreground. But the leaves of one wild rose are turning yellow, while the other one is loaded with red hips.

Aside from those hardy native wildflowers, here are five low-water plants that can prolong color power in xeric landscapes:

Beargrass. Beargrass is a woody succulent from Mexico that resembles an ornamental grass in the garden. Although plants in California and the Pacific Northwest also are called Beargrass, the ones that thrive in Mexico and New Mexico are of the Nolina family and typically are hardy down to zone 5. High Country Gardens has just introduced a new cold hardy species Nolina microcarpa, or Big Beargrass. Not only is the foliage evergreen, but as the creamy flowers fade in late summer, they turn an earthy pink. The plant attracts pollinators and reaches up to 2.5 feet in height.

Nolina beagrass
Beargrass, or Nolina, is a woody succulent that looks more like a graceful ornamental grass. Image courtesy of High Country Gardens.

Firestick Euphorbia  or “Sticks of Fire.” The Euphorbia tirucalli “Rosea” is a succulent usually grown as a houseplant, at least in any climate colder than zone 9. In warmer zones, the plant makes a stunning accent in a xeric rock garden. If you grow it as a container plant, you can add it to your summer and fall landscape by setting the pot out until the temperature hovers near freezing. The Fire Sticks plant is native to South Africa and grows well in Arizona and warmer zones of California and a few warm spots in southern New Mexico. The red color comes on as temperatures cool. If you do choose to plant Fire Sticks in a container, be aware that the plant can reach heights of 6 feet.

Nandina. Also called Heavenly Bamboo, Nandina is a favorite evergreen shrub around the country. Although it grows in part shade to full sun, the more sun you give nandinas, the more color you’re likely to see. Most nandina are evergreen and grow slowly, up to 10 feet high under some conditions, but compact varieties are available for nearly every zone. In the arid Southwest, nandinas tend to grow and spread less. Sunset has just added a compact variety called “Lemon lime” (Nandina domestica Alba) to its Western Garden collection. Hardy in USDA zones 6 through 9, this stunner has bright lime green new foliage that fades slightly but remains green.

flirt nandina
Flirt Nandina (Nandina “Murasaki”) from the Sunset Western Garden Collection. Image courtesy of Sunset.

Woods’ rose. It’s wild, but I love it. The Rosa woodsii is a rose hip-producing machine fills with delicate pink blooms in summer that somehow seem to leave even more hips than spent blooms from fall through winter. It’s as bright as any berry bush and a haven for birds, pollinators and wildlife. Of course, you can harvest the rose hips or leave them for the color and critters; the hips provide an excellent source of protein and energy in the winter. There are several native varieties of the Woods’ rose that can adapt to climate and natural water availability.

rose hips on Woods' rose
Here’s a close-up of the Woods’ rose in the center of the top photo. Who needs flowers when berries this color last all fall and winter, or until the birds eat them all?

Sedum. Sedum, or stonecrop, is a versatile group of evergreen succulents. Most of them are even more attractive in fall and winter when they darken or produce seed heads. One variety, Autumn Joy, is even named for its favored fall color. The flowers emerge in summer as a lovely pink color, but gradually turn a deep rust. Autumn Fire is a new variety of Autumn Joy with light green leaves and deeper red fall flowers. Both the foliage and flowers provide unique fall and winter interest in the garden on this xeric perennial. It comes in various heights and colors.

dragon's blood sedum
Dragon’s blood is a groundcover sedum we planted to spread over rocks. This one looks great beneath a native chocolate flower and fading desert zinnia.

Some People Learn the Hard Way: Too Much of a Good Thing

Gardening is fun. Planting is fun, and looking at flowers is really fun. Harvesting what you and the rain worked so hard together to grow – priceless. Trimming, thinning and getting rid of plants is far from fun.

I have learned the hard way this year, however, that I have to curb my enthusiasm. Too much of a good thing can go bad – quickly. And it’s not just because I’m busy working and trying to keep the garden up. I’m talking about some imbalances that occur in the garden when you plan and plant, and then nature takes over.

Mexican hats reseed
The Mexican hat is a prolific reseeder here in New Mexico. It’s a fun annual, but we have more than we need.

Below are a few lessons learned about having too much of a good thing that I hope will help beginners or other overenthusiasts. First, my disclaimers, caveats, poor excuses:

  1. Our place is big.
  2. This is only our third summer here, and we are still trying to get the weeds and gophers under control.
  3. Climates here are extreme, usually dry, with temperature ranges of more than 40 degrees in one day and a strange pattern this year in early summer.
  4. Did I already say that gardening is fun?

Planting too many of the same species hosts pests

First of all, I have written in previous posts about how filling in with annuals can add inexpensive color to your garden. Seeds cost little, and in our garden, they’re free! That brings me to another problem I have pondered several times – the line between weed and wildflower. We’ve got gaillardia, (blanket flowers), Ratibidia columnifera (Mexican hats) and cosmos growing as volunteers all over our garden. There are a few other annuals, but these three amigos would take over if we’d let them. And I almost did. I couldn’t bring myself to destroy a “free” plant. After all, it added color to the garden with no water. Tim drew the line on any growing in the walkway. I could accept that. But I should have done a better job of thinning the plants. The Mexican hats were hosts to hundreds of cucumber beetles. And I would go to deadhead the gaillardia (which could take valuable time away from my favorite activity – weeding) and find an entire stalk covered with flea beetles. These tiny black insects have been damaging my tomato plants.

flea beetle damage to tomato plant
I’m pretty sure this is a flea beetle and damage from it. This tomato is in a container about 15 feet from all those flowers. So far, the damage is tolerable.

Lesson learned: I can keep and love each of these annuals, but I need to thin them early on. Having a few host plants for the bugs might keep them off of young tomatoes, since the annuals come out earlier. But having 20 gaillardia plants is like putting up a billboard on the freeway advertising free flea beetle lodging. Variety is healthier and prettier.

Too much of a good thing robs resources

It’s important to thin seedlings in a vegetable garden, and equally important to space plantings in a xeric garden. When you plant too closely together or let annuals (or perennials that have not been trimmed enough) grow too closely together, a few things happen.  First and foremost, the plants get too little air circulation. I imagine this is more of an issue in some climates than others, or plants native to humid climates can take wet leaves and roots better than plants native to places like New Mexico. But I know most of our xeric plants can’t take it. If we get rains late in the day combined with clouds and cool evening temperatures, which is typical of the high desert, the leaves don’t dry off.

If there is little air circulation, this can increase risk of bacterial and fungal diseases in plants. Powdery mildew, which is characterized by the white or gray patches on leaves that resemble talcum powder, can occur even without rain. High humidity in typically warm, dry climates can cause the disease if plants have little to no air circulation. A plant might grow so large that it shades another plant, Even worse, if plants are too close together. one plant might sneak drinks from the other, or require more water, causing your truly xeric plant near it to have poor health or die from too much water!

Lesson learned: Thin, thin, thin! And no matter how small a seedling or new plant from the nursery appears, take time to learn its mature size. Then consider that in its new surroundings, including the mature size of the plants around it. I think I am going to strap a measuring tape to my jeans next spring.

vegetables mature
Can you spot where the melon ends, the tomato begins, the cucumber ends, the pepper begins… The good news is that there is no row on one side and plenty of space on the other, so at least these plants get air from two directions. Better planning next year.

Hedging your bets can be a lot of work

I planted 11 tomato plants. The first step is admitting you have a problem. Now, I want some credit for hedging my bets, because I had to pull up a few of the tomatoes. Some were not very strong seedlings, but I gave them a try. In retrospect, I probably should have thrown out those seedlings. Weak plants attract predators, and that’s a big lesson from all of this. I feel really badly about wasting the water to try to get them going. Our spring weather likely didn’t help (see “disclaimers” above), but I also might have lost some to poor thinning of suckers or trimming of bottom branches, which provided an on-ramp for snails and bugs. Maybe it’s the nurturer in me, but it’s fun to care for the tomatoes that have made it and to give away the fruit we can’t eat. Other plants are easier to put away for winter, including basil, beans and cucumbers.

Still, I need to plan more carefully next year. Nearly all of the water has come from the sky, including what we’ve harvested. And I’ve used a drip system for much of the well water used. But I’ll approach the vegetable garden plan more carefully next year, unless I find a way to make money growing tomatoes. If I decide to do that, I’ll have to pull up most of those blanket flowers…

too many blanket flowers
Aren’t these blanket flowers pretty? Notice two different color combinations. But having this much together (and more in other areas) is a little too inviting for bad bugs, and I have lots of plant variety for bees.

Lesson learned: Take the next six months to plan, or at least to forget how much time you spent trying to get it right.

And, as always, I want to reiterate this point: There are no dumb gardeners, and I hate to see lists and posts with titles such as “Dumb Gardening Mistakes”. I have seen careless moves or gardeners, but that’s different. If you try something and fail with your best effort, at least you tried. Research, learn from your mistake and try again!

Favorite Xeric Plant: Butterfly Bush

What’s not to love about a plant named for the butterflies it attracts? The butterfly bush (Buddleia) has much more to offer as well. It also attracts bees and plenty of hummingbirds. The plant is a long-lasting perennial in several zones and it’s easy to care for.

butterfly on buddleia
A butterfly enjoys nectar from a purple buddleia bloom.

To me, the buddleia is like a magical shrub. There’s something kind of free-flowing, almost messy to its shape, and to how rapidly it grows on its woody base. Despite its sometimes uneven appearance, the buddleia makes a perfect centerpiece or backdrop in a xeric garden. Ours sits in the center of a forefront bed, where we can watch hummingbirds and butterflies visit from our patio, but I have seen the attractive bush used well against walls and walkways throughout New Mexico.

buddleia in bloom
The full butterfly bush in bloom in July, in zone 6B.

About Buddleia

There are several cultivars of butterfly bush, and several colors of the showy flowers. A dwarf buddleia usually reaches about three to five feet in height, but the fountain buddleia grows up to 12 feet tall, is adapted to higher altitudes (above 6,500 feet) and has longer flower spikes than the typical six to eight inches. Most of the New Mexico buddleias bloom in variations of lavender, plum or purple. And I find the foliage attractive, having a kind of muted, silvery-green color and texture that brings to mind giant sage leaves.

Buddleia bush bloom
I love the shape of the large flowers. Hummingbirds circle them to retrieve nectar from individual blooms.

Caring for Butterfly Bushes

Buddleia is a drought-tolerant plant that should only need supplemental watering until established or when temperatures are consistently above 85 degrees and, of course, rain is scarce. I seldom or never water mine except after cutting it back in late winter/early spring.

Though you don’t have to deadhead the blooms, you can trim off the seedheads once they’re spent to encourage new flowering. I usually don’t bother, as my plant seems to produce for most of the season. I just give mine that drastic haircut in late winter as soon as I see a little bit of new growth on the bottom stems; it shoots up in height as soon as temperatures warm.

pruned butterfly bush in early spring
Here’s the same bush as shown above, in early spring (seriously, in the lower right corner near the sundial). It loves the heavy prune!

Nearly every buddleia is hardy in zones 5a to 9, depending on the cultivar and the microclimate you place it in. I recommend talking with a nursery representative or a landscape designer before selecting a buddleia to make sure you choose the best size for your location or vice versa. If I didn’t cut ours back nearly to the ground each year, it would block most of our garden and view!

How To Determine Watering Depth

Gardening books and plant tags often tell homeowners to “water the plant to a depth of xx inches.” That’s all well and good, but since I am not a gopher and don’t have x-ray vision, how do I know how deep water goes when I soak a tree or bush? And why is it important?

Overwatering is not just wasteful, but can harm plants. Take the tomato, or don’t take it if it has cracked from overwatering or inconsistent watering. Using a well can help ensure that you water your tomato the same depth each time, assuming the water flow is fairly slow and steady.

tomato plant with well
A tomato well holds water in place and helps me keep track of the amount I water each time. That’s important once the fruit starts growing.

Of course, there are plenty of calculations you can do, including soil tests. But there are easier ways to find out. For small ornamentals and container plants, just dig your finger in and check the soil. Most plants need water when the soil is dry down to a half-inch or so. Of course, the best way to know whether a plant needs water is to know the plant! Depth is not even an issue for xeric plants that rely on natural rainwater only, at least not once the plant is healthily established.

xeric-plants-need-no-water
These xeric plants need no water. The nighstock and gallardia came up from volunteer seeds, and an agave, prickly pear and green santolina fill in the background.

If water pours out the bottom of a container, you probably are overwatering or adding water in too quickly or forcefully. Picture the same effect in the ground. So slow down the water to give your plant time to get acquainted! When the water pours out the bottom instead of dripping, it washes important soil nutrients out with it.

For a lawn, there are plenty of tips to help conserve water, and the best strategy is to run a short cycle, wait the length of one cycle, and run another short cycle. You’ll know if your cycle is too long if you note any standing water or runoff. Running a short cycle prevents waste, and by waiting, you give the first cycle’s water time to soak down to the turf’s roots. The second application of water can push remaining moisture a little deeper, where it will be retained.

Trees need the deepest watering of all, and Arizona’s Water Use It Wisely program has a great method for determining watering depth that we used last year when we planted a new Chinese pistache (Pistacia chinensis):

  • Water your tree as you normally would, and about an hour later, push a soil probe into the ground. Since you might not have one of these lying around, you can use a screwdriver or a piece of rebar long enough for the depth you need to measure, plus a few bonus inches to help retrieve it when you’re done.
  • Mark your homemade probe or rebar before pushing it into the ground, premeasured with the recommended depth (such as 12 inches or 30 inches).
  • If your rebar goes in easily to the recommended depth, you’ve watered long enough. If not, add some water until the soil softens.
testing watering depth
We gently hammered a piece of rebar in the well area to check watering depth. If it goes in easily, your soil is soaked through. You can also use a soil probe.
  • Note how long you left your hose or drip system on and the approximate flow (slow, medium, trickle…). That way, you won’t have to keep measuring the depth, at least not for the same plant, and you’ll know about how long to water next time.
determining watering depth for tree
We used plastic tape to premark the depth on our homemade soil probe.

Start Small on Your Xeric Landscape

If you’re not an experienced gardener or feel overwhelmed by the prospect of starting a landscape from scratch or switching your entire landscape to a xeric one, why not start small?

Time, money and inexperience should not keep gardeners from enjoying a few plants in their yard. I sometimes can’t stop bemoaning the trend in believing that xeriscaping is the same as “zeroscaping.” Again, it’s not!

Even new, young gardeners and urban dwellers can enjoy a few blooms or edibles without busting their budgets, schedules or water resources. Try these tips:

  • Start with containers. If you have little space, but crave fresh herbs, enjoy a few bright blooms next to you while you savor your morning coffee outside. Or enjoy the view of hummingbirds hovering over a flower by outfitting your patio or balcony with a few brilliant containers. You could add a long, thin box with your favorite low-water kitchen herbs and a tall, round container with a salvia for color and pollinator interest. Or try a geranium, which uses a little more water, but lasts year-round in your container if you bring it indoors to a sunny location.
mint and lettuce containers
Mint in a container — where it belongs! Friends gave us these two transplants. That’s a baby mesclun lettuce mix to the right.
  • Take it one area or bed at a time. If the idea of going completely xeric in your garden is too much to handle at once, take baby steps. Convert a small area of your lawn from grass to gravel and native plants, or from high-water grass to native grass, gravel and native plantings. Or take out grass along a sidewalk or driveway and create a path with a few ornamental grasses and perennials. An easy way to conserve water is to divert rain from a downspout that pours onto, say, a driveway so that the water instead flows to a tree already in your landscape. Find plans for dry river beds with rocks to ensure the water flows to your tree.
  • Choose one or two hardy xeric perennials a year. I’m not the best person to advise patience, but if you’re short on budget and time, choose just a few hardy xeric plants to start your garden off right. The best choices depend on where you live and your USDA zone, along with the microclimate for the location you plan for the plant. Choose a perennial, a plant that will live through your winter and bloom again for at least two years. If this is an early attempt at gardening for you, go to a local nursery, where the staff can show you a few natives for your area that are hardy and easier to grow. Then go by size, bloom color, water and sun needs, maybe overall care (like deadheading) and your general reaction to the plant. There’s nothing wrong with choosing two of the same plant if you love it. Repetition can be just as attractive in a xeric landscape as complementing textures and colors!
dianthus perennial
This Dianthus next to our bird fountain needs little care and no supplemental watering, but comes back each year. In fact, a new plant showed up in another bed about 15 feet from this one.
  • Buy seeds instead of annual plants. This early in the year, at least in most zones, you still can have plenty of success with seeds for annuals to complement your perennials. There are tons of great xeric wildflower choices that grow from seeds, saving you lots of money. Instead of buying several six-packs of petunias or marigolds, pick up a seed packet of cosmos, zinnias, poppies or a native wildflower mix. Seeds need more attention and watering at first, but the flowers usually reseed for several years. And even though seeds in packet eventually expire, we’ve had success with old flower seeds.
blue flax
I can see this stunning blue flax (Linum lewisii) from my office. The damp spot on the ground is an area of red flax seeds we sowed.

Of course, if you can go big, do it. There are plenty of professionals, books and sites dedicated to xeric landscaping.

How To Water Mature Trees

When drought strikes, it’s tempting to cut back on watering of established trees or stop watering altogether. And maybe water restrictions in your area force your hand. I hate to see it happen, because trees can offer many benefits – most notably shade for homes to cut down on energy use, and shade for other plants to keep them alive and in need of less water. Of course, you can’t beat the enjoyment of sitting under the shade of your favorite tree. I won’t even get into how depressing it is to see dying trees in front lawns…

Ideally, your lawn has only native trees, and especially xeric varieties. In that case, the trees adapt to conditions more easily. Some survive on rainwater alone, but most need a deep watering about once a month during the heat of summer.

desert willow tree xeric
The desert willow (Chilopsis linearis) is a perfect xeric tree for warm to hot desert climates. This one is from a Tucson, Arix., garden.

To water your a mature tree that requires irrigation, avoid a common mistake — watering only near the trunk. Trees do not have tap roots, but instead have a root system that extends out from the tree, more or less mirroring and extending just past, the tree’s branches above. So, when you set out your hose or set up a drip or soaker system, begin near the trunk, and then work your way out to the edges of the tree’s canopy. Scroll down in this handout on caring for trees from Colorado State University for a photo of a soaker hose layout.

To water deeply, you have to water slowly. That means setting your hose or irrigation system to deliver the water at a lower rate for a longer period of time. To reach the roots, the water needs to penetrate the ground to at least 12 inches. If you’ve ever seen roots growing at ground level, they’re probably doing so because the tree is receiving too little or too shallow watering.

Don’t dig a hole around the tree to help get water to go down deeper. The hole allows air in and dries out roots!

If possible, avoid using a sprinkler to water trees. In addition to producing shallower roots, the sprinkler wastes water by dispersing it into the air, where it evaporates. And some trees are subject to leaf diseases from constant watering. The only time I ever spray a tree or bush is if it has aphids, and I give it a fine-water spray in early morning to wash the aphids off.

If you can’t reach a tree with your hose, you can drill a few holes in a 5-gallon bucket and carry it out to your tree. The water will flow more slowly through the hole than if you pour the water on the ground. Move the bucket out and around the tree’s base with each refill.

apple tree along river.
This apple tree is hard to reach with the hose, but we don’t water it because it is along the river bank and the roots take up plenty of water. This year, it had twice as many blooms and may give us some fruit. Trees can help preserve water sheds.

If you want to save tap or well water, reuse! Direct roof water to a tree using the downspout and a dry river bed. Save shower water in 5-gallon buckets (with no holes – you have to get them outside!) but only use the water that flows while the shower warms up, not any soapy flow.

If you have other clear water to dispose, such as kid or dog pools, empty the water onto tree roots instead of a random place in the yard.

Favorite Xeric Plant: Ornamental Grass

When xeriscaping, you can add plenty of interest with varied textures and heights by including a few ornamental grasses in your landscape. We’re always tempted to think first about flower color, but less about interesting foliage. Placing a few ornamental grasses in a xeric landscape or container can add nearly as much impact as a pop of purple with less watering and maintenance.

Choose an ornamental grass that is native to your area, or a similar climate or condition, in place of a shrub or perennial flower. One of my favorite features of grasses is that they can grow tall and move in the wind. In containers, they often add height or contrast to draping and flowering annuals. Warm-season grasses seed out and provide winter interest, even if the foliage browns. They need shearing once a year in spring, a little water to jumpstart growth, and they’re off. If you choose one that’s not native to your area, such as the big-box store selection I found for my containers, make sure it can at least survive with less water or other conditions that differ. You might not get flowers or as much growth, but the grass will survive at least for the summer.

rush grass in container
I like to place ornamental grasses in container arrangements to add height and texture. This juncus is all I need to add interest to a petunia mix and continuity between the pots.

Another benefit of ornamental grasses is that they can serve practical purposes in a garden. Use them for erosion control by placing a small grouping at the bottom of a slope or terrace – and go for a medium-water selection such as Feather reed grass “Karl Foerster” (Calamagrostis arundinacea) here, since the rain or irrigation run-off from above supplies the extra water the plant requires.

feather reed grass
Karl Foerster feather reed grass that was planted a few weeks ago in our rock garden . It already looks great, but will add feathery blooms in summer. It should survive our winter (zones 5 and 6).

Other great locations for grasses are along steps, pathways or corners, in front of dark walls or fences, and anywhere they will catch sunlight and breezes.

Sedges, rushes and some hardy bamboos also fall into the ornamental grass category when landscaping. Just be sure to check the zone, native location of the plant, and especially the sun and water requirements before planting the grass. Some actually do better in marshes – not a good choice for xeriscaping!

Easy care

Grasses are among the easiest xeric plants you can have in your garden. They’re mostly free of pests and diseases. And although I love ornamental grasses, I have seen some gardens with only grasses and gravel. I think you need one or two other xeric plants to break up the look, but I’m not a professional landscaper. To my eye, just gravel and grass in a garden screams “dry!” It’ so easy to complement a low-water grass with a salvia, penstemon or gayfeather.

Some cool-season grasses bolt in the heat, but trimming off their seedheads can rejuvenate the plant, much like clipping off flowers of herbs to force growth back into leaves. Most ornamental grasses are warm-season selections, best planted in the spring. They need a little more water, up to once a week for xeric choices, for the first month or two. After that, water deeply only every few weeks or once a month in the hottest summer weeks. Some will spread, and it’s best to try to divide or dig up unwanted volunteers before they clump too tightly. Other than that, just cut back as directed. Allowing several grasses to overseed in winter could add to your fire hazard, so keep that in mind if you have them near your home or a commercial building.

big bluestem grass before strawbale wall
Newly constructed strawbale wall with xeric plantings. The big bluestem grass on the right foreground got much taller and flowered (see below).

A few xeric grasses

Silky threadgrass (Stipa tennuifolia). This hardy grass grows in all types of soil, uses little water, and loves full sun. That’s a bonus, since the silky seedheads reflect sunlight as they sway in the breeze. One caution for silky threadgrass is its high potential to reseed. That’s a plus in an untamed garden, but not in a more formal xeric landscape.

Big bluestem (Andropogon gerardii).  This is one of our personal favorites. It can reach heights of four to five feet in summer, when it also rewards you with purplish flower spikes that emerge between the beautiful greenish-blue leaves. Some selections require more water than others, so check with the nursery or on the tag for details. Some are highly drought tolerant and thrive down to zone 4.

big bluestem flower heads
The flower stalks of big bluestem grass are purplish, contrasting well with the greenish-blue leaves.

Dwarf fountain grass (Pennisteum alopecuroides). Purple fountain grass (P. setaceum) is a particular favorite of these dwarf varieties, but only makes it as an annual in our zones (5 through 7). Others fare better, although an unusually cold winter could kill them. Most have bright green foliage with bottlebrush flowers. Examples are “Hamelin,” a compact, mounding variety with ivory and gold flowers and “Moudry,” which has brownish-black flowers. One caution: You might have to protect dwarf fountain grasses from rabbits if they visit your xeric garden.

Altitude and Wind Affect a Plant’s Water Needs

If you’ve ever gone skiing or hiking in the mountains of the Southwest, you’ve heard the warnings (or ignored them and learned the hard way). Drink lots of water, more water than you normally drink. You also might have noticed that you became breathless a little more quickly. All those warnings aren’t just designed to impress flat-landers or to make up for exertion. There’s science behind high-altitude dehydration of people and plants.

Low Pressure Causes Evaporation

Air pressure is lower at higher altitudes, and that means that moisture evaporates more quickly. It evaporates from lungs and from the soil and roots around plants. Add the fact that most high-desert and mountain climates also are low in humidity, and you’ve got to adapt to a new environment or nearly pass out. The same goes for your landscape, which is another reason to stick with native plants. These guys have toughed it out; they’re not just here for a weekend getaway! If you do choose non-native cultivars, plant them sparingly, and try to use them in protected areas, which leads to my next point.

 

snow on southwestern mountains
My daughter took this photo of snow on the mountains along the Arizona-New Mexico border one December. A holiday snow does not mean a humid climate.

Why Not Add Some Wind to the Mix?

Luckily, winds are worse in New Mexico on the plains than in the mountains. But how about in the high desert? Because of the wide temperature variations – warmer days and cool evenings, desert air can be a little unstable. Anyone driving through rural Arizona and New Mexico is likely to see a few wind farms, a smart renewable energy choice for our state.

Windy air contributes to evaporation. As wind speed increases, plants react by upping their rate of transpiration, which is the plant’s loss of water as it’s absorbed through the roots, up to the leaves, and out the leaves as it evaporates. More than 90 percent of the water a plant absorbs is lost by transpiration. It’s inevitable with photosynthesis.

wind spinner in New Mexico garden
This wind spinner is calm today, but we had to permanently shorten the stake to stabilize it because it almost took off in flight or bent in half a few times this spring.

It’s easy to imagine that wind makes plants drier, as anyone who lives in a windy, arid climate knows when they constantly apply lotion to their skin. Science also explains the effect of wind on evaporation. First, it’s helpful to recognize that plant evaporation increases humidity to an extent. If you’ve ever been in a greenhouse or a tropical plant exhibit, you can feel the humidity as you walk inside.

When the water that travels through a plant reaches a plant’s leaves, it seeps through tiny pores on the underside of the leaves. By hanging out there, the vapor adds to the relative humidity of the air close to the leaf. Kick up the wind, and the leaf moves around, so that it spends time in drier air. Of course, if the air outside is humid that day, the wind won’t have as much effect. But how often is it humid around here? Anyway, high wind, combined with low overall humidity and full sun, can rapidly dry out your vegetables or ornamentals before you know it!

xeric wild rose
No wonder so many xeric plants have smaller leaves. Less transpiration occurs and more energy can go into the plant’s health and blooms. I love this Wood’s rose (Rosa woodsii)., also called a wild rose or Fendler’s rose.

Native Plants Adapt

Native plants adapt to soil and climate. So what about succulents? I won’t get into a long biological discussion, mostly because I am not a biologist or botanist. But one reason that succulents often have small leaves and large stems is to reduce transpiration so they can survive in dry, hot deserts. Others, like the aloes, have a different type of epidermal layer that doesn’t allow for rapid transpiration. It’s amazing how well plants adapt to their environments; if only I could adapt to winter…

Aloe leaves
These aloes have larger leaves, but they lose less water to evaporation than do typical plants.

If you have a non-native that takes slightly more water, remember what I said earlier about protection. Place the higher water user where it’s more protected from wind. If it can take some shade, at least in the hottest afternoon sun of summer, that will help too. Check out past posts for more water-saving tips. And these tips apply to growing vegetables and other edibles in wind and high altitude. The good news for us is that our winds calm slightly by summer.

Use Mulch To Conserve Water In Your Garden

When you put away a gallon of paint or the leftovers from dinner, you always cover the container. By sealing the paint can or plastic storage container, you lock in moisture. It keeps your paint from drying out. Same goes for your spaghetti with pesto (not to mention sealing in the “aroma”…).

Your plant roots can benefit from their own covers, and that’s where mulch enters the picture. Much like the top layer of paint in a can, air dries out the soil at ground level. Add wind and heat, and water can evaporate quickly from desert gardens in particular. Mulch helps insulate the soil to keep it cool and minimize evaporation. The layer of mulch also protects the area around the plant’s roots from the forces of nature. In other words, when the rain comes, it won’t pound the ground, eroding dirt away. Instead, it hits the layer of mulch, then trickles down to the ground. Use an organic mulch and each time it rains or you irrigate, the water carries some nutrients for the roots to take into the plant as well. Need more reasons? Mulching cuts down on weeds, and weeds compete with your plants for water. Plus, they are such a pain.

shredded bark mulch
Mulch cools and moistens barberry, photinia and ice plants in Albuquerque, N.M., bed.

To truly insulate and cool plants takes about three to four inches of mulch material. It depends on the type of material you want to use. If the mulch is fine, such as bark cut to smaller than an inch in size, go only about an inch or two deep. The same goes for grass clippings. Your roots also need some air to thrive! So be sure to avoid use of landscape plastic under your mulch in any areas where you will plant. The plastic is great in walkways, but not in your beds or under trees.

When piling mulch around plant or tree roots, cover the entire area to which the roots extend. For trees, you need to go out about as far as the tree’s canopy. And don’t place the mulch all the way up against the trunk of the tree or stem of the plant. Leave a small opening close to the plant.

mulch around tree
Water is less of a concern in this Northeastern garden/iris farm. But I would worry about how closely the mulch comes to this tree trunk.

Mulches also can look attractive and add to landscape design. Be careful about mulches you choose and social media posts with ideas for repurposing materials as mulches. Some are harmful if applied directly to vegetables and other plants or introduce weeds to your garden. And if your helpful neighbor offers fresh chicken or horse manure, remember that you shouldn’t apply it hot. Add it to your compost, and eventually to the vegetable garden.

gravel around yucca
In the desert of Tucson, the rock around this xeric yucca is probably more for looks, erosion control and night-time heat retention.

We’ll break down some types of mulch in a future post, but if in doubt, check with your local extension office or master gardeners.