Last week in this column we suggested creating a swale in your home garden to capture rain and practice effective water conservation. If you have been inspired to start planning a swale, you may be looking forward to the fun of selecting plants for this garden feature.
Note that our merciless summers require additional irrigation for even drought-tolerant native plants while they are getting established. A spare but regular drip-irrigation line for the first two summers will improve survival rates.
Cool-season grasses and herbs to line a grassy swale or the banks of a rock creek:
- Sedges (Carex species) and rushes (Juncus species) for sun
- Yerba buena (Clinopidium douglasii) for part-shade
Deep-rooted, larger grasses to anchor:
- Deer grass (Muhlenbergia patens)
- Native fescues (Festuca californica, F. idahoensis, F. rubrica)
- Creeping wildrye (Leymus triticoides)
Perennials that tolerate winter moist, summer dry conditions:
- Douglas iris (Iris douglasii)
- California fuchsia (Epilobium canum)
- Prostrate manzanita (Arctostaphylos uva-ursi)
- Buckwheats (Eriogonum species)
- Fleabane daisies (Erigeron species)
- Yarrow (Achillea millefolium)
- Common monkeyflower/aka sticky-monkey (Mimulus aurantiacus)
- Yellow monkeyflower/aka seep mimulus (Mimulus guttatus)
- California coneflower (Rudbeckia californica)
- Hummingbird sage (Salvia spathacea) and other salvia species
Drought-tolerant ferns for shade
- Polypody fern (Polypodium californicum)
- Western sword fern (Polystichum munitum)
- Wood fern (Dryopteris arguta)
Shrubs and small trees for banks
- Hybrid rockrose (Cistus skanbergii)
- Barberry (Berberis aka Mahonia pinnata)
- Toyon (Heteromeles arbutifolia)
- California coffeeberry (Rhamnus californica)
- Gooseberry (Ribes speciosum)
- Wood rose (Rosa gymnocarpa)
- St. Catherine's Lace (Eriogonum giganteum)
- Redbud (Cercis occidentalis)
- Mountain mahogany (Cercocarpus betuloides)
- Red twig dogwood (Cornus sericea)
- Ceanothus species
- Manzanitas (Arctostaphylos species)
UC Master Gardeners of Butte County are part of the University of California Cooperative Extension (UCCE) system. To learn more about us and our upcoming events, and for help with gardening in our area, visit our website. If you have a gardening question or problem, email the Hotline at mgbutte@ucanr.edu or leave a phone message on our Hotline at (530) 538-7201. To speak to a Master Gardener about a gardening issue, or to drop by the MG office during Hotline hours, see the most current information on our Ask Us Hotline webpage.
The on-going drought is leading many gardeners in our area to include drought-tolerant plants in their gardens, or even design wholly drought-tolerant landscapes. Here are some tips for selecting, planting and caring for plants that prefer dry conditions.
If you have a drip system installed, you can offset the emitters to keep the crown dry or deliver water directly to the roots of the plant by locating a piece of plastic watering pipe (any dimension you have around) from ground level to the bottom of the root ball. Slide an emitter inside that pipe, and voila! You will be safely watering your plant and avoiding crown rot. If you already have a dry garden set up with emitters, make sure those drippers are not getting the stems of your plants wet.
If you are planning to put in a dry garden, summer is not the best time to do it. The optimum time to plant a dry garden is between November, when the first rains begin to fall, and February. Planting during that period gives plants a chance to establish roots before the summer heat arrives, and before the soil begins to dry out.
When putting in new plants, one method to ensure that the stem and crown remain dry is to “plant” a plastic nursery pot (like the one the plant came in) next to the plant – about ten inches away from the stem – leaving one to two inches of the pot above the soil line, so the bottom of the pot is in line with the lower part of the plant's root ball. Keep this pot empty, and when you water, water inside the pot instead of at the base of the plant. Water will seep through the holes in the pot and water the roots of the plant. After the first winter, the roots will have developed and the plant will be able to survive with less (or no) water, at which point you can pull up the pot and fill in the hole.
Once in place, water plants weekly for the first year; after that they can grow with just an occasional watering. Some will thrive with no water at all, except that which Mother Nature provides.
Consider some of the following plants for your dry garden, and keep in mind that many California native plants are drought-tolerant.
Shrubby plants for placement in full sun include lavender; Jerusalem sage (Phlomis fruiticosa); Euphorbia; cotton lavender (Santolina chamaecyparissus syn. S. incana); scutellaria; kniphofia, which is also known as red hot poker or torch lily; bottlebush (Callistemon spp.); germander (Teucrium); rock rose (Cistaceae); yarrow; coneflower (Echinacea); dianthus; artemesia;wallflower (Erysimum); spirea; lilac (Syringa vulgaris); ceanothus; flannel bush; mint bush (Prostanthera rotundifolia); flowering quince; and bear grass (Nolina). In addition, almost all of the butterfly bushes (Buddleja spp.) will grow water-free or with little water, and many (but not all) salvias are drought-tolerant – check with your local nursery.
Shrubs well-suited to shady locations include daphne (Daphne odora) which resents a wet crown, and Oregon grape (Mahonia aquifolium).
For ground cover in dry shade try Epimedium spp., which has tough leaves and star-shaped flowers and will grow in shade; mayapple (Podophyllum peltatum); and lamium (L. galeobdolon).
The availability of drought-tolerant plants may vary, so check with your local favorite nursery to see what they currently have and/or plan to stock.
New Master Gardener 2021 Workshop Series is about to begin! The Fall Series kicks off in September with brand new workshops on Drought Triage, Fall and Winter Vegetable Gardening, and Berry and Grape Care, plus workshops that have been popular in the past, including Irrigation and Maintenance, Propagation, and Garden Guide and Journaling. Workshops are free; most will be held outdoors at the Master Gardener Demonstration Garden at Patrick Ranch. Numbers of participants will be limited; Covid safety protocols will be followed. To registered (required) and for more details on the full Fall Workshop Series (including a four-parter via Zoom in October on the subject of Landscaping for a Future with Fire), visit our workshop webpage.
By Susanne von Rosenberg, UC Master Gardener of Napa County
When I first moved to Napa 14 years ago, autumn rains arrived fairly reliably around the middle of October. As we are all painfully aware now, autumn rains have been starting later and later…and sometimes not at all.
There is no rain in the near-term forecast, and the National Oceanographic and Atmospheric Administration (NOAA) Climate Predictions Center foresees a 33 percent chance of below-normal rainfall through November coupled with a 60 percent chance of above-normal temperatures. The longer-term prediction for our area is for slightly below-normal rainfall.
The change in rainfall pattern we've been experiencing, with rains coming later than they used to, is consistent with what climate-change models predict. While we can expect roughly the same amount of rain, we will wait longer for it and it will come in fewer, more intense events.
So we need to get used to longer dry seasons. On the other hand, we need to be prepared for heavy rains. How should we adjust our gardening practices to address this change?
Let's talk about an extended dry season first. It's definitely a good idea to continue all the water- conservation practices that we instituted during the last drought. Choose drought-tolerant plants, including natives that are adapted to summer-dry climates. Install proper irrigation systems, such as drip irrigation, to water only those plants that truly need it and in the amount they truly need.
Adjust your watering according to the season. With cooler, shorter autumn days, plants require less water, even if it isn't raining. Mulch your plants to keep the soil cool and reduce evaporation.
We also need to reconsider our fall watering habits. It used to be possible to stop watering trees by late August and many other plants by mid-September. With the change in climate, you now need to continue to water until the rains finally arrive. Also consider our fall heat and low-humidity periods. Look for signs that your plants need water. Drooping leaves and/or dull leaves are two primary indicators. Get to know how your plants show they are thirsty.
How much and how often should you water with this new climate? For annual plants, simply test the soil with your finger. If the soil feels moist one to two inches down, you do not need to water yet. Keep checking and you'll soon have a sense how much water your plants need in this cooler season and how quickly they dry out when we get Diablo winds.
For trees, you can either dig down six inches to see if the soil is dry (this is the best way to check), or simply extend the time between watering. If you were watering your trees once a month in the summer, you might wait five to six weeks for the next round, and then six to seven weeks (mid- to late November) for the next round. Still no rain by New Year's? It might be time to water again! Even our native and other drought-tolerant plants may need supplemental water when rains are delayed.
More frequent heavy rains are another outcome of climate change. We will need to be able manage more rainfall on our properties. Heavy rain can damage soil structure, wash away topsoil and produce standing water in low or poor-drainage areas. You can protect your soil structure by mulching. (Yet another benefit of mulching.) Observe how water flows on your property during a heavy rain. Your goal is to slow down the flow, which you can do by spreading it out, and also by including areas where you intentionally allow the water to pool and infiltrate. Overall, the better your soil, the more rainfall it can absorb and the more water it can hold. Organic mulches do wonders to improve your soil – so, yes, keep mulching.
After a heavy rain, you may see water pooling in areas where you don't want it. In that case, you need to improve the drainage in that area. The best approach is to divert water from that area and to create additional opportunities for water to drain away. You can raise the soil level, dig small swales or create shallow berms. Small changes can make a big difference. You may also find, as I have, that as you improve the soil, your standing-water problem will diminish and eventually disappear.
Gardeners are a resilient and persistent bunch. With preparation, we can manage some of these climate-change challenges.
The UC Master Gardeners of Napa County 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.
- 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.
Blame the drought followed by ample rain
Local nurseries and growers are scrambling to keep up, but demand — especially for specific cultivars — has caused an extreme shortage of many sought-after plants.
With most of the drought water restrictions now removed, people are rushing to replace the plants they lost in the drought.
Many people also took advantage of rebates and took out all or part of their lawns. To qualify for a rebate from the state or local water providers, the lawn had to be replaced with plants from an approved list. Each plant was rated for its water efficiency and rebate programs required homeowners to plant a set percentage of their yard and obtain a certain point value based on the plants they chose.
Plants with the highest point values were in high demand and sold out quickly. Growers have been scrambling to catch up, but the heavy, frequent rains have put local growers behind in their planting, which has significantly delayed availability.
Viktoria Gleason, Green Goods Buyer for Summerwinds Nursery in San Jose, says homeowners are driving what growers are producing.
“Now,” she says, “even national growers like Monrovia are growing California lilac, manzanita, ceanothus and even Western redbud. That wouldn't have happened 10 years ago.”
Acacias, especially ‘Cousin Itt', Chinese pistache and some crape myrtles, were at the top of the point list and are now virtually impossible to get.
If you are looking for great dry shade shrubs try Loropetalum (fringe plant), which comes in many sizes and colors. Many cultivars of Pieris (lily of the valley) offer bicolored leaves and dainty, bell shaped flowers. There are salvias in every size and color, and even one for deep shade.
Trees that should be readily available include Tristania laurina (water gum), which is slow growing with fragrant leaves; Arbutus ‘Marina' (strawberry tree), which has beautiful red bark, profuse pinkish white flowers and red edible fruit that provides interest all year; and Olea (European olive), which is well-suited for our Mediterranean climate. Options include fruiting, non-fruiting and even a beautiful weeping variety, Olea ‘HidShurtleff.'
Wendy Calhoun, Buyer for Yamagami's Nursery in Cupertino, says in addition to picking the right plant for the right area, people need to understand their irrigation systems.
“Most people apply too little water, way too often,” Calhoun says.
Plants thrive with infrequent but deep watering. A good rule of thumb, she says, is to apply twice the container size of water once a week. A 1 gallon plant would get 2 gallons of water per week. In extremely hot weather you might need to double that amount twice per week, but no more.
Proper watering is the most critical factor in growing healthy plants. Most plants, especially drought tolerant ones such as lavender, rosemary and California natives, fail in their second year, Calhoun says, because of over watering.
Curtis Ferris, General Manager at Soquel Nursery Growers in Soquel, says the drought has actually been good for growers and consumers.
“People are replacing their thirsty lawns with much better options and we hope they continue to do so,” Ferris says.
by UC Master Gardener Rebecca Jepsen
Photo: Rebecca Schoenenberger
This article first appeared in the May 20 issue of the San Jose Mercury News.
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