- Author: T. Eric Nightingale
Planning a drought-tolerant garden can be a challenging endeavor. Knowing which plants to use and where to plant them is difficult as information and advice can vary significantly. However, there are a few simple things you can do to make the process easier.
The first task is to become intimately acquainted with your garden. Watch the way the sun moves and where the shade falls throughout the day. It may seem obvious that how much sun a plant receives will affect how much water it uses, but not all plants labeled for low water use will thrive in full sun.
Knowing the locations in your garden that receive shade from summer heat can greatly affect the health of your plants and the maintenance required to keep them looking attractive.
Note how wind moves through your garden. Evapotranspiration, the loss of water through plant leaves, increases significantly with high, hot or dry winds. On a cloudy yet windy day the plants in your garden could dehydrate more than you expect.
Finally, get up close and personal with your soil. Check its water retention by digging a hole about a foot deep and wide and filling it with water. Hope for the water to percolate through in about an hour, signifying good drainage.
Many drought-tolerant plants, especially succulents and cacti, will rot if soil drains too slowly. Conversely, if the soil drains too readily, it can be difficult to keep even low-water plants adequately hydrated.
All of these factors will help you form a picture of how water will be utilized in, and move through, your garden. This knowledge is a useful tool when choosing new plants.
When working on creating a drought-tolerant garden there are some preconceptions it is best to discard. When many people think of a garden, the image that comes to mind is of a classic English garden. This is understandable as modern home gardening and many of its traditions originated in Europe.
But England has a different climate than Napa, and it is not realistic to expect our gardens to look like English landscapes.The plants found in English gardens are often not good candidates for a Napa Valley garden, least of all a drought-tolerant one.
Many of the best-known annual plants are thirsty in our climate, as are many popular perennials such as hydrangeas, camellias and gardenias. Tropical plants, while visually stunning, are often troublesome as well. Even if they are not labeled as requiring a lot of water, the relatively low humidity in Napa Valley can make it difficult to keep them healthy.
Changing our expectations for our gardens does not mean lowering them. A garden can use less water and remain visually pleasing, lush and colorful. In a sunny location, shrubs such as salvia and lavender can be placed among large succulents such as aloe and agave. The contrast of soft and sharp textures is pleasing to the eye. The salvia will bloom most of the summer, while many aloe, such as Aloe capitate, bloom in the winter.
Many popular groundcover-type plants have shallow roots and need frequent watering. These can be easily replaced by a clumping or vining succulent. A favorite of mine is ice plant, Delosperma cooperi, which produces a carpet of purple-pink blooms from spring through summer.
Identifying plants that work in a drought-tolerant garden is easy after some practice. Generally speaking, plants with large, glossy leaves are a poor choice. These plants will lose a lot of water to evapotranspiration and are prone to sunburn. Plants with dusty or fuzzy-looking leaves are much more adapted to hot, dry conditions.
The roots of a plant can also tell you something about its water needs. Small, shallow roots will need more frequent watering than large, deep-burrowing ones. Never hesitate to gently remove a nursery plant from its pot and inspect the roots. They are a key indicator of plant health.
An important bit of information often missing on plant labels is the term “once established in the ground.” Succulents excepted, a potted plant will usually need more water and fertilizer than the same plant in the ground. Many drought-tolerant shrubs survive by growing broad or deep root systems. It takes at least a year for new plants to develop a useful root system, during which time they will need additional water.
Knowing these facts about your garden and the plants in them, as well as altering your perception of how a garden should look, can make an enormous difference in your relationship with it. You can minimize required maintenance and reduce your stress, leaving only the pleasure of enjoying the beautiful space you have created.
Next workshop: “Home Vineyard: Part 2” on Saturday, September 14, from 9:30 to 2:00 p.m., in Calistoga. Learn techniques to maintain your new or existing home vineyard. Workshop location will be provided after registration. For more details & online Registration go to http://napamg.ucanr.edu or call 707-253-4221.
The UC Master Gardeners are volunteers who provide UC research-based information on home gardening and answer your questions. To find out more about upcoming programs or to ask a garden question, visit the Master Gardener website (http://napamg.ucanr.edu) or call (707) 253-4221 between 9 a.m. and noon on Mondays, Wednesdays or Fridays.
By T. Eric Nightingale, UC Master Gardener of Napa County
I have recently become interested in the plant family Aizoaceae. It is a positively huge family, consisting of many sub-families. The plants under the Aizoaceae umbrella are mostly of the low-lying, groundcover type. For this reason, they are sometimes known as carpet weeds, although I have more commonly heard them called ice plants.
Some members of this family are small, almost rock-like, in appearance. These plants are informally known as mesembs, a nickname derived from Mesembryanthemoideae, one of the Aizoaceae sub-families. The plants we casually call mesembs are not all members of this sub-family, however.
Mesembs are truly unique and curious plants. They are relatively small, with a variety of odd shapes, colors and textures.
One type of mesemb you may recognize are the so-called stone plants, or Lithops. Lithops do in fact resemble the rocks among which they live, providing them with useful camouflage. They are native to arid southern Africa, where they survive on little water.
Lithops have evolved to hide from thirsty animals, as well as to better store their water. They do this by growing mostly underground, the tops of their leaves almost flush with the surface of the earth. This way, they are easily overlooked by predators and also shield themselves from much of the day's sun and heat.
The tops of their leaves are flattened and semi-translucent, allowing light to enter the inside of the plant, where it is used for photosynthesis. What a truly amazing adaptation.
Mesembs of the genus Aloinopsis are some of my personal favorites. The stubby leaves on these plants have odd, bumpy dots on them. The result is either a jeweled look or something resembling the texture of a dog's nose. To me they have always looked somewhat alien, as if they initially evolved among the rocks of Martian hillsides.
When planted among other succulents in a garden, Aloinopsis may easily be overlooked. This modesty changes in winter, however, when they flower. The yellow, orange or pink blooms shine vibrantly in the sun and are truly eye-catching. While they are generally similar to daisies in shape, the stamens of these flower form a cone at their center—another way that Aloinopsis is an attractive oddity.
Another of my favorite mesembs is Oscularia deltoides. It is a sprawling groundcover, almost vine-like. I like to plant it at the edge of a pot, letting it spill over. The leaves are an attractive blend of gray, blue and green and contrast nicely with the slightly reddish stems.
When I first saw O. deltoides I did a double-take, asking myself what I had just seen. The triangular, toothed shape of the leaves made it look more like a crystalline growth of some sort rather than a plant. I have also heard it compared to coral, a resemblance easy to see when it becomes large.
This mesemb is possibly one of the easiest to grow. In my experience it needs little water and seems to revel in hot sun. During the spring, when the plant is practically covered in pink blooms, it quickly becomes the focal point of the garden.
By now everyone in California has heard of the benefits of drought-tolerant gardening. Succulents do double-duty, however, in that they are also ideal for fire-wise landscaping.
As they are especially squat and water-retentive, mesembs are an ideal addition to any California garden. While some gardeners consider them more challenging to care for than other succulents, that's only because they have different needs.
Most mesembs have a short dormant period, either in winter or summer, when they need almost no water. If you water them then as you do the rest of the year, they may rot. They generally like a lot of sunlight but some are prone to burning if exposed to late-afternoon sun. And of course, as with other succulents, mesembs need loose soil with good drainage.
Once you get to know your plant, care is easy and maintenance is fairly low. All you have to do is relax and appreciate what these unique succulents bring to your garden.
Free Talk: UC Master Gardeners will discuss “Growing Summer Vegetables” at the Napa Public Library on Thursday, March 7, from 7 p.m. to 8 p.m. Learn what you can grow in the summer, what to plant and when, and how to have a harvest all summer long. No registration required.
Workshop: The U. C. Master Gardeners of Napa County will present a workshop on “Growing Spring and Summer Vegetables” on Saturday, March 9, from 9:30 a.m. to 11:30 a.m., at the University of California Cooperative Extension, 1710 Soscol Avenue, Napa. Do you want nutritious, easy-to grow and utterly fresh food from your garden this spring and summer? Learn what the garden needs to successfully produce spring and summer vegetables from seeds and plant starts. In addition to growing basics and hands-on activities, this program includes watering, fertilizing and harvesting tips, with a dash of Integrated Pest Management for pest and disease control. The delight of growing your own groceries is matched only by savoring them at harvest. Online registration (credit card only); Mail-in/Walk-in registration (check only or drop off cash payment).
Workshop: The U. C. Master Gardeners of Napa County will present a workshop on “Summer Vegetables” on Sunday, March 10, from 1 p.m. to 3 p.m., at Yountville Community Center, 6516 Washington Street, Yountville. Get tips for growing your own summer vegetables. Learn some basics, get keys to success, and do hands-on activities to learn about new varieties and review old favorites. Enjoy healthy vegetables taken straight from your garden to your table. The delight of growing your own vegetables is matched by savoring them at harvest. Online registration or telephone the Parks & Recreation Department at 707-944-8712.