Groundcovers might not be as sexy or exciting to plant as some ornamentals, but the low-growing plants are useful and can really add to a xeric garden’s look and function.
Here are a few reasons and ways to use groundcovers:
Water savings: erosion control. On garden slopes, a low-growing groundcover slows the flow of water. Use one that’s relatively drought tolerant and the plant absorbs enough water from the flow to get by. An added bonus – slopes can be difficult to mow, and a low-growing groundcover needs less maintenance.
Water savings: mulch effect. Groundcovers cool the soil below and retain some moisture, which can work as a sort of living mulch under a tree or other plant that needs cooler roots.
Turf alternative: Groundcovers typically are less invasive and easier to control than grass, especially between flagstone or other steps.
Weed control. Once a groundcover blankets an area, weeds have a harder time growing in the same spot. It might not entirely eliminate them, but eventually weed seeds have a harder time getting into covered soil and receive less light.
Design element. Groundcovers can add color, year-round interest and an area of low growth in the foreground of a design or near paths. Check out this gorgeous example of creeping thyme as an alternative lawn in a xeric design.
Creeping thyme (Thymus ‘Pink Chintz’). This is an excellent choice for filling in around flagstone steps or any area that takes foot traffic (see link above). In fact, several thyme varieties are considered steppable. Creeping thyme does fine with low water once it’s established, but if it receives more water, it grows more rapidly, which might help to fill in an area.
Ice plant (Delosperma). The flowers of ice plants are delicate and bright, coming in yellow, bright pink or salmon and rust colors. Although some varieties of ice plant need a little more water than others, most can get by in xeric rock gardens. Ice plant is a rapid spreader and easy to maintain. If it grows outside the area you intend, just clip it off. Or pull up a stalk and its roots and move it to another spot in your garden.
Perky Sue (Tetraneuris scaposa). Although Perky Sue might not technically be a groundcover, it can spread enough to add floral color and evergreen foliage. I’ve seen this or a nearly identical plant called plenty of other names, including Hymenoxys scaposa, bitterweed, and narrow four-leaf nerve daisy. It’s also similar to the Angelita daisy (T. acaulis).
Prairie zinnia (Zinnia grandiflora). Also called desert zinnia, this is a favorite rock garden groundcover of mine. It has tiny, thread-like leaves and bright yellow flowers. Most of all, it spreads from the previous year’s plant; you simply remove the spent foliage as the weather warms and you see new green beneath the old. It can spread up to 6 or 10 feet.
Plumbago (Ceratostigma plumbaginoides). The best part of plumbago is its fall color. The purple flowers typically bloom in early fall and then the leaves redden. Plumbago also does best in shade or part (afternoon) shade in warmer areas.
All of these groundcovers are perennial and hardy to zone 6 or cooler. Groundcovers can require some patience or money. For carpet-like coverage, you either have to plant many of them fairly close together, or ideally space new plants according to planting instructions and wait for them to fill in. Some also have minds of their own. To me, the haphazard growth is more natural looking in a rock or xeric garden. But if you’re going for a formal look, choose one that’s easier to control, such as thyme.
Growing with organic methods is smart for lots of reasons, both personal and environmental. Although there are plenty of strategies gardeners and homeowners can use to save water with ornamentals, such as planting native and xeric plants, it’s a little tougher with vegetable gardening.
Tomatoes, for example, need consistent watering! But growing tomatoes organically can conserve water. Here are five ways how:
Organic soil retains water better. Anyone can improve their soil’s water retention by up to 5 percent by adding organic matter. It also helps to avoid use of chemicals and pesticides. Using pesticides and chemical fertilizers in gardens can throw off the natural balance of the soil, making it less able to retain moisture around plant roots and making fewer nutrients available for plants. On the contrary, planting cover crops in the fall and use of compost or other organic matter help restore valuable soil nutrients. Organic matter also helps soil structure for water infiltration and retention. Healthy soil can respond better to drought conditions.
Organic growing protects water supplies. By avoiding chemical pesticides and fertilizers, gardeners also protect the water supply. Pesticide chemicals can remain in the soil for years; some are more toxic than others and break down in the soil more slowly. The chemicals from these products can run off into bodies of water, such as rivers. And eventually, they can seep into groundwater. That might seem a distant concern to some urban gardeners, but those of us using wells live right above available water. The more chemicals that run into water supplies, the less safe drinking water is available.
Use of mulch reduces evaporation. A layer of appropriate mulch above the ground around a plant helps reduce ground-to-air evaporation, making the soil take longer to dry out. The mulch also helps cools plant roots. Using organic mulches such as bark, nut shells, compost and others adds organic matter to the soil slowly over time for an added bonus.
Organic methods can minimize erosion. Traditional gardening and farming uses rototilling and deep plowing to turn the soil before each growing season. Plowing deeply and turning the soil over can disrupt soil microorganisms, harm soil health, and place looser soils on top, where they’re subject to erosion from water and wind (think Dust Bowl). No-till methods help control erosion and build soil structure. The soils, in turn, better retain water. This can be a problem if the soil drains poorly, but a definite help in low-water regions. Not tilling involves building up beds with organic matter, much like nature does as plants drop leaves that decompose. If you want to work organic matter in, it’s best to grab a shovel. A broadfork is the best tool for breaking up compacted soil.
Growing organically creates healthier plants. Healthy soil is the foundation needed to grow healthy food. When soil has good nutrients and structure, it supports root growth and uptake of nutrients, improving plant health. Plants that are not healthy are more vulnerable to insect and disease damage. The plant might not use water as it should when it’s stressed, and the gardener certainly guesses that if a plant looks bad, it needs water. So, keeping plants healthy saves the extra water the plant needs or gardener applies in times of stress. And healthy plants keep on going, so you don’t waste water on establishing a plant that later dies from poor conditions.
Winter has come late this year, and that’s alright with me. But we’re sure to face a hard freeze soon and it’s time to protect some plants.
The first line of defense, of course, is to choose plants that are hardy down to your average low winter temperature. These plants might look dead in winter, but they come back as spring warms the air and ground. We can’t control the weather, however, so when exceptions to your typical low hit or you really want a plant on the border for your temperatures, you can help that prized plant make it through the winter. Here are a few tips:
Planning ahead helps. When placing a new plant in your landscape, be sure to consider its winter hardiness when you plant. Placing it in a warm microclimate, such as against a south-facing wall or fence, can keep the plant a few degrees warmer when temperatures dive on winter nights.
Mulching over bulbs or around the roots of perennials and even trees can help the ground retain heat. I use raked-up leaves and sometimes straw. In addition, I use rock mulch around xeric plants. The rocks absorb and reflect heat.
Sadly, we can’t all afford or find space for an actual greenhouse. You can buy or create mini-greenhouses around a few plants. Ours only need a small boost, so we often use 5-gallon buckets with the bottom cut out. We sometimes top them with wire for deer protection or cloth for extra warmth. Glass adds even more warmth and a cloche, French for “bell,” is a glass jar that can cover individual plants. There are lots of ideas online for constructing mini-greenhouses out of plastic and wood or PVC pipe, but you’ll need to remove anything that airtight as soon as the temperature warms back up following a freeze. Otherwise, condensation forms inside; the water drops refreeze and actually can damage your tender plant.
A sheet or blanket wrapped around an entire plant helps protect it from freeze on the occasional cold night. Again, this is a temporary fix. If you have an entire section of plants that need protection, it’s better to rig a system with hoops or sticks and fabric row cover. If leaving the cloth on the entire winter, be sure to use a landscape fabric that allows sun and water through. I like to open these on warm, sunny days.
Plants need to head into winter in a healthy state. That includes keeping them watered (at a reduced rate) if you haven’t received precipitation recently. Cold, windy air dries plants out and stresses them. There is no need to prune most perennials before winter. It’s best to let them die off naturally, feeding birds with seeds. You’ll trim trees while they’re dormant in winter. When freeze threatens, you can water the mulch around the plant, but avoid hitting the leaves and branches. The water in the mulch helps hold heat in. I’ve also seen suggestions of placing used plastic bottles filled with warm water around the mulch to conduct some heat during a freeze.
Bring plants inside
No greenhouse? How about the house? My largest geranium loves the sun from our bathroom window, and the humidity likely helps as well. We have so many plants to bring inside that some have to live in the garage, where it can get chilly but hasn’t gotten below freezing. If you want to invest some money, you can buy grow lights for plants that need more sun than available in your home or garage space. Spray the plants off and let them dry a bit before carrying them inside. This helps reduce the chance that bugs tag along for the ride.
Check out lots more ideas on our Pinterest boards (What’s wrong with my plant? and Greenhouses)
Microclimates can be a farmer’s or gardener’s best friend. A few years ago, I wrote about how use of microclimates, or pockets of a garden that have varying temperatures and exposures to weather elements, can expand your choice of xeric plants.
The easiest example of a microclimate is a greenhouse. Windows let sun in and walls, a roof and other strategies help maintain the warmth. Add a heating source (and enough space) and you can grow nearly any plant any time of year.
Subtle microclimates exist all around your yard and gardens. Structures and hardscaping absorb heat during warm hours and release it gradually, helping to protect plants from cold; they also can protect plants from wind. Partial shade shields plants from heat, and slopes or other topography alter how the overall climate affects a given plant.
The Zinnia Experiment
I would like to say that we planted zinnia seeds in three different places simply to later show how microclimates affected their growth and hardiness. But I’d be pushing the truth. I did plant them in several different spots to see how well they grow here and how quickly they bloom, so I can use them as an easy annual filler to add color and even more pollinators to our gardens.
So, we put seeds in open space in our vegetable farm rows, mostly for the pollinators. We also planted some on a fairly exposed raised bed in our xeric garden. Finally, we planted seeds in the lower part of the xeric garden, close to the rock wall. All of the flowers did fairly well, although the ones in the farm area had better soil and more consistent drip watering. They were the tallest and healthiest. The ones in the raised bed took longer to come up, likely because of poorer soil and an inconvenient hand-watering location. The flowers planted in the lower bed did almost as well as the ones in the farm area.
Then the frost came and the healthiest plants burned the worst. They more or less bit it overnight.
The zinnias in the raised bed were nearly as bad, but at least the flowers kept their color (I planned to take photos of them, but hard-working hubby cleaned up the bed before I had a chance.)
The zinnias in the lower bed fared the best. I doubt they will grow or flower more, but they don’t look like they belong in a horror movie.
How to Use Microclimates
The experiment helped me get a sense of microclimates on our land. We’ve always assumed that our farming area is cooler because it is in a sort of mini-valley jut above the river. The dead zinnias demonstrated we were right, especially since those plants were the most robust before the freeze hit. The flowers in the raised bed are more open to cool air; there were no other plants nearby or much hardscape to absorb heat either.
The hardiness of the zinnias in a more protected and “solarized” spot near the rocks was telling. It’s always important to think about sun and shade exposure, but sometimes we fail to consider how placing a few large rocks behind a cold-sensitive plant can help it survive winter. In vegetable gardening, for example, using fabric to cover plants creates a micro-greenhouse effect. And when growing a plant that needs a little less sun or heat, shade cloth or plant placement can lengthen growing seasons.
Microclimates, like the general climate, can vary. For example, a tree that drops its leaves provides no shade until it fills in late spring. As trees mature, they can begin shading a plant that once received full sun; it might be time to transplant a shaded shrub. Windbreaks help slow the flow of cold air streaming up a slope.
Containers offer excellent microclimates, not only because they warm up quickly, but because you can move them to solve sun and wind exposure issues, and all the way inside before the first frost.
We’re trying to add more wildflowers to our garden and create small meadows around some areas of the property. One of the challenges in choosing locations and flowers is munching deer.
Our deer population is not huge, mostly because of a previous wildfire in the forest north of us. I don’t want to exclude deer from the property and am happy to let them graze our grama and other grasses all year long. Although we seldom see the deer once summer days heat up, we see evidence of their munching from time to time.
Blocking deer is the best way to keep plants safe. But it’s much easier to fence around a tree, bush or vegetable garden than it is around a wildflower meadow. Fencing kind of ruins the effect. So, the best way to keep deer from eating the flowers is to plant “deer resistant” varieties. The quotation marks refer to the fact that our deer have not read the plant descriptions. They avoid several plants completely, but every so often, we find surprising telltale signs of deer damage. I think it’s difficult to guarantee deer resistance for most plants.
We recently ordered a deer-resistant wildflower seed mix from High Country Gardens that we’ll plant after the first hard frost. Not all of the plants bloom the first year, which is disappointing, but we’ll plant a few deer-resistant annual plants to fill in so the meadow looks colorful for a special event we’re hosting next summer. Here are some of the flowers included in the deer-resistant wildflower mix:
Yarrow (Achillea millefolium); Lanceleaf and plains coreopsis (Coreopsis lanceolate and C. tinctoria); Foxglove (Digitalis purpurea); California poppy (Eschscholzia californica); red poppy (Papaver rhoeas); and the trusted blanketflower (Gaillardia), along with several types of lupines (Lupinus) and sages (Salvia).
This wildflower mix needs full to partial sun – at least six hours of sun a day. We have a few areas that are shadier, so we’re still looking for an easy solution there. In April, I wrote about five drought-tolerant plants that love shade. Columbines come to mind, of course, but some salvias take at least partial shade and are deer resistant. Then again, some shade lovers, like hostas, attract deer. We’ve also got some rocky areas, and plan to sprinkle white love-in-a-mist (Nigella) seeds and gathered larkspur (Delphinium consolida) seeds this fall as well.
Keeping deer out of meadows
One strategy for keeping deer out of wildflower patches is to surround the area with aromatic plants that deer avoid, such as lavender or rue. There are lots of deer deterrent products; I’ve had success with Messina’s Deer Stopper spray on plants in our xeric garden that deer had previously disturbed. The product remains effective for about 30 days, but I have to remember to spray regularly for continued protection. Spraying an entire meadow would take way too long, but I think the spray could be really effective on those flowers we’re most concerned about or know deer have eaten in the past.
Finally, if uncertain about the best wildflower choices for a meadow, work with what you have. You can try gathering seeds from native plants or leave the area unmowed at the end of the season and let nature spread the seeds for you. I’ve done that in an area with a higher grama-to-weed ratio, and hope that each time I walk through it, I spread grama and flower seeds. We pulled as many weeds from it as we could to give the native plants like grama, wild blanketflowers, verbena and daisies a better chance of reseeding.
Note: Messina’s sent me a free sample of Deer Stopper spray, but did not influence my use or review of the product.
Gardeners often choose plants more for their flower color or ease of care, and that’s a great way to enjoy a garden. If you want to add interest to a xeric bed or lawn, it also helps to consider plants’ shapes and textures. Shape, or form, refers to the circles, lines and squares of plants or how you arrange plants. Texture relates to how coarse or fine a plant looks and even feels.
For example, there’s a reason why many professional container arrangements usually include a grass or similar plant with tall, thin blades. The grass rises from at or near the center of the pot, adding height. The long, slender blades of ornamental grasses also vary the shape and texture of the arrangement if it’s filled with low-growing, round flowers. You can do the same in your xeric garden.
Although it can be tough for some gardeners to adapt to the Southwest after owning lawns with formal cottage gardens, they eventually learn to love the look and easy maintenance of more native, “unsculpted” plants.
Although some landscapes look great with rows of the same plant, most xeric gardens have a more natural feel. The designer or home gardener can use a variety of low-water plants to vary shapes. For example, if you want to plant cacti and succulents in your container or garden, you aren’t likely to choose all prickly pear cacti (Opuntia). Their round pads and medium-height spread complement a spikier ocotillo (Fouquieriaceae) or a spiraling sedum groundcover.
The shapes in xeric plants typically are less defined. Still, plants have a basic shape, such as how lavender stalks form a rounded V.
Those who desire a more balanced or symmetrical look can repeat a plant. Some of the most effective landscapes I’ve seen have a row or grouping of xeric ornamental grasses. Individually, the grasses have a wispy, wild look. But when placed in a grouping, they sway in the wind together and create a clean line. Too much variety can cause a xeric garden to look more like a botanical garden full of eye-catching plants with no flow if not designed by professionals.
Foliage and texture
Many xeric plants produce remarkable flowers, and some bloom throughout the growing season. But one way xeric plants survive is with relatively smaller foliage. Less leaf area means less transpiration (water evaporating from leaves) and improved survival chances in arid climates. Still, a waterwise garden can include foliage variety in texture, size, shape and color.
Some xeric plants, such as pineleaf penstemon (Penstemon pinifolius) have tiny, needle-like leaves. These contrast nicely with nearby plants that have rounder, lusher foliage, adding varied shapes and textures to the garden.
You also can add texture with hardscape materials or yard art. Hardscaping materials include just about anything that isn’t a live plant. So, for example, you can add interest around a rock or boulder with a plant that has small, twisting or draping branches. A post fence has lines that run up and down, and I believe that a mix of small, round or trailing plants look better against it than a line of tall or upright plants. Hardscape items also add texture, such as rough rockiness or smooth backdrops.
Rhythm is an important landscape design that can be achieved with cautious repetition of shapes, curves and layers. Some of the best designs have layers. For example, you can plant a groundcover (a low-growing or trailing plant that typically spreads) in front of a shrub that has long, thin branches and few flowers.
When layering plants, or in any planting, it’s important to consider a plant’s mature size. If not, your nice round shrub might catch up to or even block the tall one behind it. It also helps to know a little about pruning. You don’t have to shape plants into animal characters, but it helps to know how to trim the plant for its health and growth (even control of growth). Otherwise, plants can later upset balance and rhythm in the garden.
Hardscaping is use of anything other than plants, really, in the garden. So it includes rocks, fences, walls, walls made of rocks, pavers, stepping stones, lighting, gravel (made from rocks) and found or repurposed objects. Did I mention rocks?
Here’s the problem: When people think of xeriscaping or converting high-water lawns and landscapes to more waterwise plans, they often turn to landscape gravel, rock borders and concrete to fill their landscape. Done! But the best xeric landscapes mix functional and attractive hardscaping with plants for full effect.
Pros of Hardscaping
I find that after touring a public or private garden, my photos often include fences, garden art and other hardscaping features. I guess I’m drawn to them. Any plant can shine when placed before a solid wall or large boulder, but those with tiny flowers and foliage really pop with a backdrop. And you don’t have to use large, expensive artwork or structures. Sometimes, all you need is a well-placed rock or container.
Aside from aesthetics, hardscaping features provide function in the landscape. Pathways lead the gardener, visitor and the eye in the best direction, or help a homeowner get from one point to another more easily. Fences and walls improve privacy and arbors and pergolas add to shade in sunny garden spots.
Finally, homeowners often put in hardscaping to minimize watering and plant care. Most nonplant items in the garden require little to no care and last for years.
Cons of Hardscaping
Replacing lawn and plant materials with hardscaping can lower maintenance, but can create too much heat in the lawn and garden. A concrete patio or gravel-covered yard is way hotter than turf and plants. That being said, a mix of both helps lower water use and costs. If done right, homeowners can enjoy their gardens and save water.
Only plant materials provide important food and pollen for animals and insects; bushes and trees also provide better shelter than the eaves of your home. Adding birdhouses and beehouses near plants can help nature’s garden visitors. Too much concrete and gravel also makes a garden seem unfriendly to people. You probably want privacy and a place to sit or walk, but don’t you also want flowering or edible plants nearby? If a big patio is necessary for entertaining, add container plants on the ground, walls or even the furniture.
Finally, be sure to consider existing trees and other plants you plan to keep when converting lawns to gravel. Trees need deep watering, and the roots stretch out at least to the tree’s canopy, which is how far out branches and leaves extend. So providing a pretty little circle of mulch around the trunk likely isn’t enough.
Some of my favorite xeric landscapes combine a few featured plants such as a shade tree or colorful bush with low-growing annuals or groundcovers that cascade over steps or rocks. Combining hardscape and plant features is a smart xeriscaping strategy and a way to enjoy your lawn for years to come.
Wildflowers that reseed are a perfect plant for busy and cash-strapped gardeners. Once you get them going in the garden, they’re sure to come back for years. The trick is to deadhead or cut the flowers for arrangements while in peak bloom and then let some spent flowers go to seed.
With that in mind, choose a few plants or seeds for your favorite low-water annual and enjoy the colorful rewards for years. Here are six favorites of mine, most of them in the Aster (Asteraceae) family:
No. 1: Cosmos
Start with annuals or easily grow cosmos from seed. They come in a number of colors, including several versions of pinks and purples and white. The flower is a native of Mexico and can reach various heights depending on the mix and growing conditions. With too much water, they get a little tall and leggy. Sow cosmos after your last spring frost. Let several go to seed in fall to feed birds and provide next year’s color.
No. 2: Blanketflower
Gaillardia, or blanketflower, is an annual or a perennial in zones 3 through 11. It reseeds in our garden and lawn. This drought-tolerant beauty adds yellows, orange and rust tones to the garden. The blooms attract bees and butterflies. Blanketflowers bloom best if the gardener deadheads spent flowers, cutting the stem just above the next set of leaves down the stalk. You can also cut the plant by about one-third at the end of summer instead of regularly deadheading. If you want the flowers to reseed in your garden, leave some dried heads on the plant well into fall.
No. 3: Mexican hat
Called Mexican hat or prairie coneflower, the Ratibida columnifera is yet another member of the Aster family that reseeds easily. Mexican hats can bloom all summer long with little to no water, adding earthy colored blooms to xeric gardens. They attract bees and are considered an herb with touted use to ease stomach pain or headaches. When planted from seed, they might not bloom until the second year, but will reseed. Because the seeds need cold to help them germinate, those dropping from a plant in fall in zones 4 through 9 stand an excellent chance of becoming new plants in spring.
No. 4: California/Mexican gold poppy
These wildflowers in the poppy family love sun and drought, but bloom best after summer rains. We call them California poppies (Eschcholzia californica). Mexican gold poppies are a subspecies of E. californica that thrive in desert settings. Both have feathery leaves and flowers about 2 inches in diameter that resemble a cross between an oriental poppy and a tubular or cupped flower. Deadheading the remaining seedhead helps them produce more flowers, but letting the seeds develop late in summer could lead to a new stunning poppy across the yard!
No. 5: Coreopsis
Yet another member of the Aster family, coreopsis is a great self-sower. It might take over a garden in the right conditions, but our Lanceleaf Coreopsis, a classic yellow bloomer, spreads nicely in our dry climate. If you want more color, coreopsis won’t disappoint. Here, Sunset Magazine lists a dozen favorites for western gardens. Some varieties such as lanceleaf are perennials, depending on zone. They’re a fun, natural looking plant with flowers suitable for cutting.
No. 6: Wild daisies
Like their relative the sunflower, native daisies in the Aster family can spread easily and pop up in unexpected locations. We have several that bloom in late fall and spread mostly by seed. The trick is recognizing these gems among a stand of weeds so you can let them grow to maturity and bloom, then reseed. Some wild daisies are invasive, but they’re easy to control in our dry climates. Bidens alba, also called common beggartick or Spanish needle, has tiny white flowers on lanky stems. They’re pretty and are touted to have herbal or medicinal uses, but as friends of mine pointed out, they have needle in their name for a reason. The seedheads not only help the flower spread, but get caught in nearly anything they touch, including dogs’ coats.
You don’t necessarily need to gather seeds from these flowers unless you want to try the plant in a different area. We’ve had mixed success with that, maybe because a particular flower tends to reseed where conditions are best for the plant.
If you’d like to grow some of these reseeding flowers in your garden, check with your local master gardeners or a regional garden book or blog to see which types grow best in your region without becoming invasive. Of course, I go with the premise that I can always thin volunteer flowers if they get out of hand. That usually only means smack-dab in the middle of a walkway…
You know, I hate to sound ungrateful. We always need rain in New Mexico, if not to water all of the grass, trees and native plants, then to replace our valuable water tables. But in a climate of extremes, especially this summer, we’ve had several weeks of too much water and cool temperatures.
Typically, New Mexico and many Southwestern states receive monsoon rain in the summer, and it accounts for at least half of the rain we receive in New Mexico and Arizona. Monsoons can start around mid-June and end late in September. Ours typically begin around the 4th of July. Monsoons consist of short but strong bursts of rain, usually in the afternoon. They’re fueled by the sun’s warming of Southwest land and nearby oceans at different rates. Water evaporation creates humidity over land, forming the clouds that then depend on temperature, atmospheric pressure, winds and mountain slopes to turn into storms.
Typical is key here, however. This year, we had few to no monsoon storms. Instead, we had unseasonably hot and dry, followed by weeks of unseasonably cool and wet. The first rains did wonders at greening up our native grasses and plants. But then in August, the rain and clouds just kept coming. We just had a break, but now Hurricane Newton has struck Mexico and its remnant moisture is headed for southern Arizona and New Mexico.
If arid areas need rain, why is so much rain bad? Flash flooding is a big problem in desert and mountain areas. But how does heavy rain affect xeric lawns and gardens?
First, plant roots need more than water to survive and thrive; they also need air. When you place a new plant in the ground, for example, you should press the soil around it lightly and avoid compacting it to the point that air can’t reach the roots. When excessive rain falls, the water replaces air in spaces around soil particles. As the water drains through the soil, air can again enter the spaces. But if the water keeps flowing from the surface, or especially pools, the spaces fail to open. Eventually, roots can be damaged and fail to even take up the water that surrounds them.
The second danger of too much water is disease. Any fungal organisms in the soil can more easily attack wet plant roots and cause root rot. Xeric plants are not used to so much water on their leaves and roots. Even leaves are affected by too much water falling and sitting on them, especially without sun and heat to dry them again. Plants are more susceptible to leaf diseases such as leaf spot or blight and have less chlorophyll, which affects appearance and photosynthesis. Eventually, poor leaf health can lead to the breakdown of most of the processes that keep a plant healthy and send energy to fruit and flowers.
Many xeric plants also like sun and a little heat. Native plants have adapted to the Southwest monsoon patterns that usually rule their growing season: A gradual, sunny warm-up in the morning, followed by scattered building clouds. They get a nice drink in the heat of the afternoon, and then the sun comes back out and the air and ground warm up again. This pattern helps dry the plant and soil, and gives the plant plenty of heat and sun. Although nights can be cool in many areas of the high desert and intermountain regions, mornings warm up again after sunrise. Extended periods of cloudy, cool weather lead to too little sun for plants, along with too little heat than they need to thrive and flower.
Even edibles can have problems from too much water. They’re susceptible to root rot, depending on lots of other factors such as soil quality. Leafy vegetables and herbs flower early. Tomato fruit tastes better with moderate water. Too much water, especially inconsistent amounts, can cause fruit to crack.
Keeping Xeric Plants Alive During High Rain Periods
Make sure all plants, and especially those susceptible to root rot, are in soil that drains well. Raised beds, mounds or berms, and suitable containers can help drain soil around plants much better than compacted soil. If you’re not sure how well your soil drains, you can typically tell when it pools or soaks in hours after heavy rains. Or you can try the test in this handout from TreePeople that times water drainage.
Provide air circulation. We all have a tendency to place new plants and seedlings too close together. You might as well get as many cucumbers as possible in the limited space you have, right? But lack of air circulation in crowded plants hides bugs, causes the leaves to maintain moisture, and even can shade ground around roots. Wet conditions harbor new problems that native plants in particular can’t take.
Another problem with extended periods of rain is weed control. Although mostly native, the darn weeds seem to love excess moisture. And before you know it, they crowd and wrap around important garden plants or shading grasses. It’s hard to control them if the ground is too wet to mow or you can’t even get outside.
Build raised beds or transplant susceptible plants to higher ground. We’ve had some drainage problems near our patio and are working on a dry river bed to divert water away from the house foundation and down into a grassy area, where it can soak grass and eventually add to groundwater. One step we took was to divide a blue mist spirea (Caryopteris clandonensis) and move the portion near the patio onto a small burm. The xeric plant is so much happier now.
Whatever you do, don’t water! Turn off drip or sprinkler systems during and after periods of rain; it’s just the responsible thing to do. And don’t assume that yellowing leaves indicate the need to water. With too much water, the leaves look sort of floppy, but too little water usually causes dry, brittle foliage.
Finally, don’t stress. You can’t control weather, so simply keeping your plants as healthy as possible within time and weather constraints is all a gardener can do!
A droopy, wilting plant. It’s a gardener’s instinct to automatically assume: It needs water. And sometimes, that’s a good instinct. But low-water plants just as easily can be killed by kindness as by neglect.
For example, several problems with tomato fruits are caused by too much water, or especially irregular watering. Plants, like people, need some regular hydration. You wouldn’t avoid drinking water for five days and then gulp down a liter, right? One reason drip systems are effective is the consistency (assuming you set a timer) of the amount of water they deliver, along with the slow rate of flow and the fact that they water the soil/roots and not a plant’s leaves. The delivery and slow flow help retain more moisture and nutrients around the roots.
What’s the prognosis?
There are reasons other than drought stress that cause plants to wilt, including problems with the roots. That’s why plants you’ve just transplanted from seed or a nursery container tend to wilt for a few days or weeks. The roots suffer some damage when taken from a pot and replanted. Understand that this is part of the natural course of the plant’s life and help it through without stressing too much (meaning you, not the plant). Even though a plant is waterwise, it still needs extra water until the roots heal and begin to grow, more efficiently pulling water into the plant. If the ground is dry at root level, the roots can’t do their work. Plants that are overwatered sometimes wilt, too, further complicating the “diagnosis.”
Speaking of, most gardeners jump to the worst possible scenario when determining a plant problem. Although disease is a possibility, look not only for symptoms of a particular wilt or fungal disease, but also for possible causes. Do you have evidence of bugs that might have damaged leaves or carried a disease to your plant? Is the plant getting enough air circulation? Is water running off and away from the plant? Has it just been super hot for several days?
The best way to distinguish drought stress from other causes of wilt is by looking at and feeling the soil. Damp soil means the plant has water available; adding water at this point likely won’t help. You should feel an inch or two below the surface. One way is to stick your finger in the dirt to about the first knuckle joint.
Prevent plant stress
When a plant needs water, it’s more susceptible to damage from bugs and diseases. Pests attack the weak. You can prevent plant stress from underwatering by:
Checking the soil as mentioned above; see if there is water for the plant.
Looking for signs of underwatering. These usually include leaves turning yellow and brown, and even falling off. Typically, drought stress begins with lower leaves.
Thinking about the plant’s environment and how it might have changed. Is it windy and hot or muggy and cool in the evenings? Did you last water a plant in the afternoon out of necessity instead of your usual morning routine?
Using a meter or records when in doubt. We have an inexpensive moisture meter for our farm area. If nothing else, it helps confirm or deny my suspicions about the need to water and gives me a basis for comparing soils or drip rates around certain plants. Keeping records of watering, fertilizing and other activities can help manage and diagnose plant problems.
It’s always better to water before a plant wilts, and not to wait until wilting occurs. Although plant roots need to seek water, they also have to find it! When no water is available in the soil around them, plants can begin reacting with wilt, slowed growth or flower and fruit production, and other signs.
Finally, remember there is no hard and fast rule on watering. Much of the advice I see comes from areas that are more humid, cooler, less windy, and at lower altitude than our conditions here in New Mexico. Having said that, you can create conditions that help plants retain moisture, mostly by ensuring healthy soil and mulching. Containers need a little more frequent watering because they dry out faster than the ground. Water container and landscape plants slowly so the moisture drips instead of flooding down. You probably only need to add water to a container when the top few inches of soil are dry.