By Cindy Weiner, Butte County Master Gardener, July 29, 2016.
One approach to dealing with drought conditions in the garden is to turn to native plants that are well-acclimated to our local environment. Some gardeners new to planting natives may be concerned that these plants might require special care, but in general they need not worry. While some natives can be difficult in the garden, most are not, and many are very easy to grow. Three local landscape designers specializing in native plants offer the following suggestions for “no fail natives.” In addition to being easy to care for, these particular plants give a threefold return on one's investment: they are attractive, versatile, and provide valuable support for wildlife in the garden.
Eve Werner, landscape architect and owner of Eve's Garden Design, likes to use coffeeberry (Frangula californica) as a screen, background or hedgerow. Its blackish berries resemble coffee beans and are very attractive to birds. This evergreen shrub can grow to six to ten feet tall and wide although the cultivar ‘Eve Case' is smaller, only reaching about five feet. It is native to Butte County and grows in Upper Bidwell Park. Werner says, “This adaptable plant thrives in full sun to shade with monthly to no summer irrigation.”
Jason Mills, owner of Ecological Solutions, suggests, “If you're looking for an evergreen shrub, why not try giving the local and less commonly used hollyleaf redberry (Rhamnus ilicifolia) a shot?” Hollyleaf redberry has small serrated leaves, resembling holly. It grows best in full sun or partial shade. The flowers are small and inconspicuous but develop into beautiful red fruit, which provide food for birds. It grows five to ten feet tall and needs no summer water once established.
Mills and Whittlesey like using the large perennial bunch grass deergrass (Muhlenbergia rigens). Whittlesey says, “I use deergrass to bring a rhythm and flow into a garden. When in flower in later summer, it has a stronger architectural form which holds through the winter months. It combines readily in front of larger shrubs or as a foil for small shrubs and perennials.” Deergrass forms a dense clump to 4 feet tall and wide in full sun or light shade.
Growing natives can be easy if you give careful consideration to the plant's cultural requirements. Mills states, “In the end it all comes down to putting the right plant in the right spot. We look to nature and try to match the conditions (substrate, moisture, light exposure) found in remaining intact habitats when we create our designs and implement native landscapes. When you get it right, you'll know, as they thrive for years to come with little to no water and maintenance and provide crucial resources for wildlife along the way.”
By Barbara Ott, Butte County Master Gardener, July 15, 2016.
Most gardeners are aware of the national USDA Hardiness Zones and the Sunset Climate Zones. The USDA zone map is primarily used to assess if a plant has the ability to survive freezes, while the Sunset zones take into consideration a number of other factors as well, includinglength of growing season, timing and amount of rainfall, humidity, wind, and summer high temperatures, as well as winter low temps. Especially because our local Mediterranean climate experiences a great number of very hot days each year, Butte County gardeners must also pay attention to whether a plant can survive full summer sun plus excessive heat.
Most plant labels will state the lowest USDA zone in which the plant will survive in the winter. And a label might indicate that the plant can tolerate (or even require) “full sun.” But how many plants have been purchased because they fall within the appropriate USDA zone and seem to thrive in full sun until that “full sun” climate includes a run of days when temperatures exceed 100 degrees? A conscientious gardener works hard at placing plants in ways that insure strong growth and survival over time. And yet many gardeners who have turned to Mediterranean or native plants because of our prolonged drought may find that even some of these plants cannot survive full sun plus full summer heat in the Sacramento Valley. It can be frustrating to do everything in one's power to help plants survive, only to find that those carefully-chosen and maintained plants cannot handle full sun plus extremely high heat.
Heat damage is subtle. Plants die quickly when they freeze, but when they experience too much heat they can hang on in a sickly manner as flower buds dry up and fall off; leaves droop and are munched by insects; leaves lose their green coloring; and roots stop growing. Plants dying from heat can linger on for years, becoming increasingly stunted and chlorotic, until finally enzymes fail and the plant dies.
How can you find out how much heat a plant can take when placed in full sun or partial sun? The American Horticultural Society (AHS) has developed a tool that can help us choose appropriate plants for our climate and guide us in placing those plants in optimum locations. This is the AHS Plant Heat-Zone Map.
The AHS Plant Heat Zone Map is based on twenty years of daily high temperatures gathered from nearly 5,000 weather stations across the country by the National Climatic Data Center. The color-coded map indicates 12 nationwide zones based on the average number of days annually that an area experiences heat days in which temperatures exceed 86 degrees Fahrenheit. When temperatures top 86 degrees, plants begin showing signs of physiological damage caused by heat. The AHS Heat Zones range from Zone 1 (less than one heat day) to Zone 12 (more than 210 heat days). Chico and Oroville are in AHS Heat Zone 8 (91 to 120 days over 86 degrees); Paradise and Magalia are in AHS Heat Zone 7 (61 to 90 heat days). The AHS Plant Heat-Zone ratings are based on the assumption that a plant is being adequately watered at all times, because heat damage is linked to an insufficient amount of available water. The ability of a plant to survive in a Heat Zone (or even outside of its designated Heat Zone) can be affected not only by water use, but also by light exposure, day length, air circulation, and proximity to nearby structures, among other factors.
For example, placing a “full-sun” plant in a morning-sun only location might be appropriate if you are in the plant's hottest recommended heat zone. And, because on a hot day fast-moving air can quickly dehydrate a plant, taking fences or other structures into consideration when locating a plant, or even planting hedges to cut down on rapid air flow, can be helpful strategies in our somewhat challenging climate.
Alas, at this date most nursery plant labels do not indicate their AHS Heat Zones, but that is changing. Thousands of garden plants have been coded for heat tolerance, and more are presently being coded. Here are some examples:
Gardenia jasminoides “Veitchii.” This plant is listed as USDA Hardiness Zones 8 – 11, AHS Heat Zones 12 – 8, and Sunset zones H1, H2, 7-9, 12-16, and 18-24. That Heat Zone number indicates that it may do better in the warmer valley areas of Chico and Oroville than in the higher (cooler) ranges of Paradise and Magalia.
Kerria japonica is listed as appropriate for USDA zones 5-9, AHS Heat Zones 9-1, and Sunset zones 2-23; while it falls into our local climate zones on each of these zone maps, in Chico and Oroville our AHS zone of 8 means that placing Kerria where it will get some relief from hot afternoon sun (even though it is a “full sun” plant) may be well advised.
One useful site that lists AHS Heat Zones for plants is http://www.learn2grow.com/plants.
For more information on the American Horticultural Society and its Plant Heat-Zone Map, see AHS Plant Heat Zone Map.
By Cindy Weiner, Butte County Master Gardener, July 1, 2016.
While this more traditional style is beautiful, it is not particularly well-suited to our Mediterranean climate with hot, dry summers, and therefore requires irrigation several months of the year. But there are many areas on campus where native plants are featured in the landscaping, and these areas are multiplying in tandem with changes in the built environment of the campus. New plantings of natives and compatible non-native, water-smart plants are generally added to complement new buildings (such as, most recently, the new Arts and Humanities Building) or where lawn has been removed. According to Alonzo, the goals for landscape remodeling projects are sustainability; bringing harmony to the campus; blending the contemporary look with the more traditional look of older plantings; clustering plantswith similar water requirements together in an effort to conserve water (an approach known as hydrozoning; and educating visitors about the “new” (sustainable, water-wise) California landscaping.
The Phenology Garden is located in the raised planting bed at the east entrance to Holt Hall. Phenology is the study of periodic plant and animal life events related to climate conditions, such as flower blooming or bird migration. Planted in 2014, it is used by students to participate in research involving long-term data collection. It contains primarily native plants that require no supplemental water once they become established. Foothill penstemon, alum root, snowberry, sticky monkeyflower and western dogwood are some of the plants in the Phenology Garden.
Just a short distance away, at the northeast side of Holt Hall, a new garden was planted this spring to replace a former
lawn. Designed to resemble a forest understory layer, it contains giant chain fern, bigleaf maple, western dogwood, redbud and western columbine growing under existing mature trees.
Two large planting beds between the new Humanities building and the Performing Arts Center were also installed in the spring. These contain shade-loving natives such as coffeeberry, evergreen currant, bearberry, Oregon grape and creeping mahonia planted in long swathes.
A new planting area combining both natives and non-natives will replace some of the lawn between the Acker and Shurmer gyms and Yolo Hall and will be installed in the fall. Keep an eye on these new areas to watch these gardens grow and mature.
By Michael-Anne Foley, Butte County Master Gardener, June 17, 2016.
Are you are confused by plant catalogs or magazine articles using different climate zone maps to describe the appropriate environment for particular plants? You are not alone.
The USDA plant hardiness map divides North America into 11 hardiness zones. Zone 1 is the coldest; zone 11 is the warmest. When you order plants from catalogs or read general garden books, you need to know your USDA zone in order to be able to interpret references correctly.
The 2012 USDA Plant Hardiness Zone Map compiled by the USDA and Oregon State University is based on the annual average minimum winter temperature over a 30-year period, and is divided into zones of 10 degrees each, further sub-divided into “a” and “b” zones of 5 degrees. Since 1990, the zone boundaries have shifted in many areas. Zones on this relatively new 2012 map are generally 5 degrees Fahrenheit (a half zone) warmer than those indicated on the previous map. This data was accumulated over the 30-year period before 2005; the more recent zone map based on this information was released in January of 2012.
The USDA map is now available as an interactive GIS-based map, for which a broadband Internet connection is recommended, and also as static images for those with slower Internet access. Users may also simply type in a ZIP Code and find the hardiness zone for that area. For example, using the USDA Hardiness Zone map, Chico, Oroville and Paradise are all located within Zone 9a (minimum winter temperatures of 20-25 degrees Fahrenheit). Although this is a useful plant hardiness index it has some important drawbacks: for example, it puts the Olympic rain forest into a zone with parts of the Sonoran Desert.
Gardeners in the western United States are sometimes confused when confronted with these 11 Hardiness Zones created by the USDA. A more useful index is the 24-zone climate system published in the Sunset Western Garden Book in collaboration with the University of California. The Sunset climate zone map for gardening was devised in the mid-20th century for thirteen western states. It has been expanded to include areas across the U.S., providing a more useful alternative to the USDA zone system.
The 24 Sunset Zones are determined by a number of factors to help gardeners identify the most appropriate plants for their needs. Winter and summer highs and lows are used to provide information about the temperature extremes in the region. Weather patterns like humidity, rainfall and heat are considered. The Sunset Zones also take into account specific environmental conditions like prevailing winds, day length and soil type.
The greater precision of the Sunset system is evident in our local area: Chico is in Sunset zone 8, Paradise is in Sunset zone 7, and Oroville is in Sunset zone 9. Because the Sunset zone maps are more precise than the USDA's, they are considered the standard references for gardeners in the West. So, when you purchase plants for your zone, be sure you are using the right zone map! Sunset's zones 7 and 8 are much warmer than the USDA zones 7 and 8; mixing up the systems might well result in planting the wrong plant in the wrong place.
And keep in mind that even within a city, a neighborhood, or a street, microclimates can affect how plants grow. For example, planting tender citrus against a wall that absorbs daytime heat places it in a micro-climate that is warmer than a more exposed area. The zones are a guide and a good starting point, but you still need to determine for yourself what will and won't work in your garden.
For further information, check the following websites:
By Cindy Weiner, Butte County Master Gardener, June 3, 2016.
The Alice B. Hecker Native Plant Garden at Chico Creek Nature Center was planted in the late 1980s. While some plants have been replaced over the years, many are original and were propagated by members of the Mount Lassen Chapter of the California Native Plant Society. Some of these, like leather oak and California nutmeg, are rarely seen in gardens. The garden beds represent different local habitats, such as foothill or riparian. Fully-grown Oregon ash, elderberry and redbud trees provide shade for California bush anemone, Western bleeding heart, pipevine and mock orange. Spreading daisy, soaproot and several species of sage grow in sunnier areas. This garden demonstrates how a native garden will look after a couple of decades of growth.
The gardens at the Gateway Science Museum (at 625 Esplanade in Chico) include a native plant pollinator garden planted in 2013. These plants were chosen especially for their value to birds, butterflies, bees and other insects. Many of the plants provide nectar or pollen for the adult pollinators. Some insect larvae feed on leaves. The garden includes many different species of sun-loving sages and buckwheats. Showy milkweed is the host plant for larval monarch butterflies, and several monarchs go through complete metamorphosis in the gardens each year. The Gateway Gardens have been so successful at attracting both honeybees and native bees that it is one of 60 gardens in the state chosen to participate in the Urban California Native Bee Survey conducted by the UC Berkeley Urban Bee Lab. This is an established, but still young and developing, garden.
Public native gardens such as these are an excellent resource for anyone planning a more water-wise home garden.