- 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.
The challenges of caring for houseplants are often underestimated, and the successes rarely celebrated. A flower garden is easily visible to passersby, who may stop to discuss it and compliment you on your green thumb. Indoors, however, our efforts (sometimes, thankfully) go unseen.
Houseplant care can be likened to gardening in an exotic climate, one that can be deceptively inhospitable to plant life. Indoor growing conditions, such as light, humidity and temperature, are often significantly different from those outside. While this environment protects us and our plants from harsh outdoor weather, houseplants usually find it less than comfortable.
A large majority of the houseplants at nurseries are species that originated in tropical climates. As such, they prefer warm, slightly humid environments with medium to high levels of light.
Light is the most common challenge for houseplant growers. On average, indoor light is only two percent as bright as outdoor sunlight, and often less. Our eyes are astoundingly adept at adjusting to changes in light levels; plant leaves much less so. With some exceptions, houseplants want to be as close to a sunny window as possible.
Most people keep their homes within a healthy temperature range for many houseplants. Home heating and air conditioning often dries out the air, however, causing plants to lose moisture more quickly than they would in their native climates. If your plant is near a heater or drafty area, check the soil frequently for dryness.
Misting plants with a spray bottle is a common tactic to fight dehydration, yet it is not very effective. If a houseplant seems to be struggling, place it on a shallow tray of gravel filled with water. As the water evaporates, it will provide a nice aura of moisture that your plant will love. Alternately, you can run a humidifier in your home, helping all of your green friends at the same time.
Container gardening poses unique challenges, and houseplant care is no different. Houseplant soil often develops a whitish crust, the residue of salts from fertilizers and tap water. This buildup will eventually adversely affect your plant, but you can prevent it by thorough watering. Let the water flow from the bottom of the pot, then discard the excess. This procedure will help flush the unwanted salts and keep your soil clean and healthy.
If you are anxious about keeping a houseplant alive, I recommend Zamioculcas, also called Zanzibar gem or ZZ plant. This houseplant is one of the easiest to care for that I have ever encountered. It has a unique appearance, resembling a tall, green feather. It grows in low light and with little water, which makes it ideal for people who have challenging home environments. The roots of these amazing plants are actually succulent rhizomes that divide within their pots, eventually creating more plants.
Another easily managed houseplant is Beaucarnea recurvata, the ponytail palm. It starts with incredibly dainty sprouts but can grow into an enormous, bulbous tree. Don't worry; the palm is very slow growing. It requires moderate to bright light but is drought tolerant. The ponytail palm grows so well that it received the Royal Horticultural Society's Award of Garden Merit.
If you are an accomplished houseplant grower, you may be interested in a challenge. Trachyandra is not easy to find and a bit fussy to care for, but it is an excellent conversation piece. Native to Africa, this odd specimen grows from a bulb and appears as several green corkscrews sprouting from the soil. Every time I see one of these fascinating plants I am reminded of the incredible diversity and unexpected beauty of the plant world.
Indoor gardening presents some hurdles, but the rewards are many: cleaner air in your home, the feeling of nature around you, and the knowledge that you helped something grow. Napa County Master Gardeners can help you with any questions you have and help make your home verdant inside and out.
We usually source our accompanying pictures from the anonymous web. Lately, however, we have noticed the disclaimer on every photo that it may be subject to copyright. Thus, we have begun to tag our photos with the (source of the photo.)
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.edu/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.
When clients bring sickly plants to the Master Gardener help desk, we ask about conditions in their garden. How often do they water and what method do they use?
For every inch a plant grows, there is probably an inch of roots holding it in the ground and nourishing it. In my experience, clients often water less than plants need. Ten minutes with a drip system three times a week is usually not enough.
When I was training to become a Master Gardener, our class studied how fast water drains through soil. Dry soil has tension; water moves around the surface until it can work its way into the soil. For a demonstration in class, several large tubes were filled with different soil types: sand, mulch, clay, loam and gravel. We watched water work its way down through each soil type and learned that each level had to be saturated before the water moved to the next level.
The same is true in your soil. For deep roots, water deeply.
Many vegetables develop roots that go three feet deep; several, like tomatoes, can have four-foot-deep root zones. Consequently, that is where the water needs to go.
Last year, Napa County Master Gardener Ray Sittig made drainage slits in gallon-size cans, then sunk a can in the soil alongside each of his tomatoes. He filled the cans with water twice a week, and the water slowly seeped into the soil.
Hardpan is another potential problem. Your soil's hardpan is the layer below the topsoil that is impervious to water. In my garden, it is a couple of feet beneath the surface. Hardpan was formed by clay deposited during flooding. Most of the top couple of feet of soil has had mulch, compost, fertilizer and other amendments added. Water penetrates easily but stops when it reaches the hardpan. I often push a length of rebar into the soil to see how deep it goes before hitting hardpan. In my vegetable garden, I continue watering until the rebar goes in easily.
When preparing to build raised beds, some gardeners dig the soil below the bed and work compost into the soil to break up the hardpan. Then the raised bed with its improved soil is built on top.
When I plant tomatoes, I place plastic on top of the soil to conserve water. This barrier keeps moisture in the soil, warms the soil and encourages growth. I have also used clean cardboard, cutting holes in it for the vegetable seedlings.
After planting, apply mulch to the soil surface to retain moisture. My habitat garden, which I don't irrigate, has a heavy layer of mulch. Because of that moisture-retaining barrier, it is still easy to pull weeds. One reason to remove weeds is to keep them from taking water from the plants you want.
If you have a plant problem, bring it to the Master Gardener help desk (see hours below). During the summer season, Master Gardeners also staff a help desk at farmers' markets and garden centers around Napa County. Please bring your plant sample in a plastic bag.
Workshop: Napa County Master Gardeners will hold a workshop on “What's Bugging You?” on Saturday, June 18, from 9:30 a.m. to 11:30 a.m., at University of California Cooperative Extension, 1710 Soscol Avenue, Napa. Understanding pests and blights that affect your vegetables is key to managing them. Squash that doesn't grow, tomatoes with peculiar markings, artichokes full of earwigs, plants that fail to thrive − all these and more will be discussed. Bring your own problems to show and tell and learn how Integrated Pest Management techniques can help. Mail-in/Walk-in registration (cash or check only). On-line registration coming soon.
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.edu/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.