By Jeanne Lawrence, UC Master Gardener of Butte County, July 13, 2018

Summers are getting hotter in much of the U.S., including our local environment. One way to counteract this change in climate is by planting trees to provide more shade in the summer months. But adjusting to a shadier garden also means shifting to different plant choices. While it is true that most colorful garden flowers (like roses, zinnias, poppies, and hollyhocks) require full sun, there are still many options for blooms available to the shade gardener. White flowered gardenias and pink or blue flowering hydrangeas are common shade plants in our area. Here are some less obvious selections of shrubs that are easy to care for and can provide interest in the shade garden at different times of the year:

A great small shrub for very shady areas is Sarcococca (sweet box). It is evergreen, with dark green leaves and tiny white flowers that appear in late winter or early spring and are very fragrant. Following the flowers are red berries. Once established, Sarcococca will tolerate dry shade. It is especially lovely planted in groups or as a small hedge; several of these shrubs growing together maximizes their scent, which has been compared to that of sweet vanilla. S. ruscifolia is slow growing, but can eventually reach six feet tall and wide; S hookeriana humilis is a much shorter shrub, growing to perhaps one and a half feet. This variety will spread by underground runners to create a good ground cover over time. Sarcococca is a perfect choice for deeply shaded areas under eaves and overhangs, alongside entryways, and under low-branching evergreen trees.

For a spot in the garden that would benefit from some bright color in spring and early summer, consider Kerria japonica. This is a deciduous shrub, but its bright yellowish-green stems provide color in the winter months. Triangular bright green leaves emerge in early spring on thin arching branches, followed by golden yellow blossoms that resemble small roses about an inch in diameter. K. japonica ‘Pleniflora' is commonly found in local nurseries. It can grow eight to ten feet tall and wide, with graceful arching branches covered with double yellow blossoms. Plant K. japonica in a partially shaded spot, where it will get at least four but no more than six hours of sun each day, preferably in the morning hours, or in the early evening after the hottest time of day. After flowering is completed, cut the branches that have flowered back to the ground, allowing this shrub to retain its arching habit.

The genus Spiraea includes many species that do well in lightly shaded areas in our climate. There are two main types of Spiraea: those with long, graceful, arching branches lined with clusters of tiny white flowers (these are often referred to as the “bridal wreath type”); and those with a shrubby growth habit which produce clusters of white, pink or red blossoms at their branch ends. Both types are deciduous, and the leaves of many of these species turn bright shades of red, orange, or yellow in the fall.

Spiraea thunbergii is a bridal wreath type that can reach six feet high and wide, with many thin, arching branches. In early spring, the bare branches are lined with clusters of tiny white flowers. These are followed by very narrow, inch-and-a-half-long, blue-green leaves that turn yellow or reddish brown in the fall. Another stunning bridal wreath type is the fast-growing S. x vanhouttei. On this shrub, diamond-shaped blue-green leaves emerge first, followed by flat clusters of white blossoms covering the plant in mid to late spring.

A notable shrubby type of Spiraea is S. japonica ‘Anthony Waterer.' Reaching three to five feet high and wide, it produces two-to-three-inch wide clusters of deep pink blossoms in late spring and early summer, and will produce another crop of blossoms if spent flower clusters are reliably pruned out. While ‘Anthony Waterer' has bright green foliage, similar pink-flowering varieties have been developed with quite remarkable leaf color. For example, ‘Goldflame' and ‘Goldmound' have bright yellow-green foliage, and the leaves of ‘Limemound' emerge lemon yellow, then turn to lime green.

By planting several different species of Spiraea, you can have blooming shrubs in shadier areas of the garden from early spring into summer, with the added bonus of beautiful fall colored leaves, and often, brightly-colored bare stems in winter.

By Cindy Weiner, UC Master Gardener of Butte County, July 27, 2018

Many people rely on automatic irrigation systems to water their yards. It's a practical way to deliver water to plants without having to drag heavy hoses around the yard. You can set up the controller to water in the cool of early morning while you are still asleep. You're free to leave on vacation, knowing your landscape won't suffer while you're away. Unfortunately, many irrigation systems are set up to deliver the same amount of water to all the plants on a single irrigation line, despite the fact that individual plants may have different water needs. Because plants may differ greatly in their water requirements, giving the same amount of water to every plant on an irrigation line can be wasteful. If you irrigate according to the needs of a particular plant with high water requirements, you may be overwatering the other plants on the line. Incorporating hydrozones in your garden design will help you conserve water by making your irrigation more efficient.

Hydrozoning groups plants with similar water needs together on the same irrigation line. Each line can then be adjusted to deliver the amount of water the plants need without overwatering any of them. In order to hydrozone effectively, you'll need to know the water needs of the plants you intend to use so you can group them accordingly. The Water Use Classification of Landscape Species (WUCOLS IV) is an online document maintained by the UC Division of Agriculture and Natural Resources. Based on the field experience of landscape horticulturalists, WUCOLS IV provides information on the water needs of more than 3500 plants used in horticulture in California. The original intent of WUCOLS IV was to provide guidance to professional landscapers in selecting plants for water-efficient landscapes, but it is user-friendly enough for home gardeners.

The water needs of all the plants in the database are evaluated relative to a reference standard. The reference standard is a hypothetical field of tall, well-watered cool season grass. A mathematical formula using meteorological data (such as hours of daylight, temperature, relative humidity, and wind speed) is used to calculate the amount of water lost through evapotranspiration (the combined evaporation from the soil and transpiration from the leaves). In order to maintain acceptable health, appearance and growth of the hypothetical field of grass, the amount of water lost to evapotranspiration needs to be replaced by irrigation or rain. The historical reference evapotranspiration for Chico is 8.5 inches for July and 51.7 inches annually.

WUCOLS IV divides the state into six different regions: North-Coast Central, Central Valley, South Coastal, South Inland, High and Intermediate Desert, and Low Desert. Chico and nearby cities are in the Central Valley. Within each region, plants are categorized into four different water-use categories: high, moderate, low, and very low. The categories represent the amount of irrigation water relative to the reference standard needed to maintain acceptable health, appearance and growth of the plant. Plants in the high use category need about 70-90% of the irrigation water the reference standard would require. Moderate use plants need about 40- 60%; low use plants, 10-30%; very low use, less than 10%. In Chico, low water use plants perform well with small amounts of irrigation water during the summer. Very low water use plants don't need summer irrigation except during periods of drought.

Examples of plants in the WUCOLS IV high category are birches, coast redwoods and foxglove; in the moderate category, examples include most dogwoods, azaleas and coneflower; in the low category are chaste tree, rosemary and strawberry tree; and in the very low category are olive, western redbud and toyon. Most plants in the very low category are California natives.

The WUCOLS IV plant search database (http://ucanr.edu/sites/WUCOLS/) is easy to use. From the menu on the home page choose “Plant Search Database.” That option leads to the page where you select your city by region. Under “Central Valley” choose your town from the pull down menu. Chico, Gridley, Oroville and Paradise are all listed. If your town isn't listed, choose the one nearest yours. Click on “submit” to go to the Plant Search Page. There are several different options for how you can use this page. If you want to research a particular plant, enter its botanical name or its common name and then press the appropriate search button. A plant description page then pops up with botanical name, common name and water use. A search for “strawberry tree” in Chico brings up its listing with the botanical name Arbutus unedo and water use low. Some plant descriptions include an attached photo. You can also research by plant type (growth type, California native, Arboretum All Star, etc.) and/or water use by checking off the fields of interest. Pressing the search button will reveal a list of plants with the chosen characteristics. For example, if you select tree and then search, you'll see 833 trees listed along with their water needs in Chico. If you filter by both tree and low water use, the list will have 153 results.

If you are planning a new garden, you can find the water needs of plants you intend to use in order to hydrozone effectively. In existing gardens, you can check the plants on an existing line to compare their water needs. If you need to add a new plant to a line, you can research those which will match the water needs of the existing plants. You may also find that you can reduce irrigation on lines that have plants with lower water needs. WUCOLS IV is a very effective tool to help you develop a water-efficient irrigation plan.

For more information on gardening in our area, visit the Butte County Master Gardener web page. If you have a gardening question or problem, call our Hotline at (530) 538-7201 or visit our Hotline web page.

By Jeanette Alosi, UC Master Gardener of Butte County, August 10, 2018

Puncturevine (Tribulus terrestris) is an attractive green plant with small yellow flowers commonly seen growing prostrate along the side of the road. A native to Southern Europe, it's also referred to as “goathead.” However, underneath its foliage lies danger: spiky seedpods with needle-point spikes. If puncturevine is stepped on, it is painful to bare feet and dogs' paws; it will pierce and flatten bicycle tires. Because of its spiky seedpods puncturevine is also referred to as “caltrop,” after the spiked metal devices thrown on the roadway to stop vehicles. Caltrops have four projecting spikes with one spike always pointed up; just in the right position to puncture a tire or flip-flop, hence the similarity to puncturevine seedpods.

Puncturevine is a hardy summer annual that thrives in our hot, dry Mediterranean climate, even in areas of highly compacted soil. The plants are prostrate in sunny areas but can grow upright in shade. Their small yellow flowers tend to be open in mornings from April to October. A single plant can form a dense mat up to five feet in diameter, spreading outward from a center tap root. The spiky seedpods are hidden underneath the plant. Puncturevine plants are prolific; a single plant can produce 200 to 500 seeds during the growing season. And these seeds may be viable for up to five years, leading to increased spreading over time.

Puncturevine is listed as a “C-rated” noxious weed in California. This means it is widespread and a “known economic or environment detriment.” Besides being a danger to the public, it causes major problems along roadways and agricultural lands in several ways. Ingesting the hard spiky seedpods injures the mouths and digestive systems of livestock. The leaves contain compounds called saponins which are toxic, especially to sheep. And the puncturevine's deep taproot competes for water and nutrients in croplands.

Unfortunately, there are is no easy way to control this noxious weed. For most homeowners, the mechanical control methods of hand removal or cutting the plant off at the taproot are most effective. Any seeds left on the ground must be removed by raking or sweeping. Use heavy gloves to protect hands from the spiky seedpods. Of course, as with any weed, it's best to remove it before it flowers and sets seeds. This is especially important for puncturevine, as seeds are viable for years, and can be spread by shoes or the wheels of lawn mowers or carts.

If the plants are still small and have not produced seeds, shallow tilling (about one inch) is recommended for larger areas. Deep tilling is not recommended as any buried seeds are still viable, and can lead to future infestations. Mowing is usually not effective because the plants grow so close to the ground.

Biological control using several species of weevils have been tried but are not always effective. Chemical control of puncturevine in the home garden is often unnecessary. However, in heavily infested areas, or when hand removal is difficult, herbicide may be an option.

For more information on puncturevine see the IPM Pestnote No. 74128 and the IPM Weed Gallery.

For more information on gardening in our area, visit the Butte County Master Gardener web page at: http://ucanr.edu/sites/bcmg/. If you have a gardening question or problem, call our Hotline at (530) 538-720l.

By Laura Lukes, UC Master Gardener of Butte County, August 24, 2018

Sideritis. It sounds like a medical condition, but it is actually the name of a plant genus known for its medicinal properties. And it is one of the latest additions to the UC Master Gardeners Demonstration Garden at the Patrick Ranch (10381 Midway, just south of Chico).

This spring (2018), Master Gardener David Walther, an expert on unique and fascinating plants and owner of Spring Fever Nursery, added a Dry Garden to our Demonstration Garden with the help of a hard-working team of fellow Master Gardeners. This new garden is located between the Heritage Almond orchard and the roundabout in front of the Patrick Ranch Museum Gift Shop. The Dry Garden features plants that, once established, need NO supplemental water during our hot, dry summers. Yes, you read that right.

Ideally, Walther and his crew would have planted the varieties showcased in the Dry Garden in mid- to late-October 2017. Fall and winter rains alone would establish the plants and no further supplemental irrigation would be required. But due to the delayed planting schedule, the Dry Garden is receiving some supplemental water this season. Once the rains come (usually just after Halloween), the array of plants in the Dry Garden will be left to their own devices to survive our valley summers.

Plant selection is the key to a successful dry garden. Many Mediterranean and native California species evolved specific strategies to weather the long, hot, dry summers that characterize this special climate niche. Some of these species are actually averse to summer irrigation, and will not survive without well-drained soils. (Watch this space for a future article on the qualities that make a plant “drought tolerant.”)

Walther chose about twenty species of plants for their beauty and their hardiness (see sidebar for a complete list). Among the usual Mediterranean suspects such as Santolina, several species of Phlomis, and Teucrium chamaedrys, there's a new kid in town: Sideritis cypria.

Sideritis is a little toughie that exhibits a number of desirable qualities. It is strikingly beautiful; wind and deer resistant; evergreen (with interesting foliage year-round and contrasting flower spikes in summer); can take full sun and heat; and prefers to be dry all through the summer.

The particular Sideritis species Walther chose for this Dry Garden is Sideritis cypria, whose common name is Cyprus ironwort or Cyprus woundwort. The literal translation of Sideritis from the original Greek is “he who is made of iron.” As its species name indicates, Cyprus ironwort is endemic to the eastern Mediterranean island of Cyprus; specifically, it grows on rocky cliffs and outcrops along the slopes of the Pentadaktylos Range in the Kyrenia Mountains, which run along the northern coast of the island. (More fun with words: Pentadaktylos translates as “five fingers” – the shape which the range is said to resemble.)

The suffix “wort” comes from a Middle English word (wyrt) for root, and nowadays indicates a plant that has been historically used for food or medicinal purposes. According to Oliveology, an online resource devoted to “sharing and enjoying the culinary treasures and gastronomic traditions of Greece,” Sideritis was well known to ancient Greeks, particularly to the pharmacologist/ botanist Dioscurides, the philosopher Theophrastus, and to Hippocrates. A number of sources note that in ancient Greece it was commonly used to treat wounds, especially those inflicted with iron swords or arrows.

A few moments on the internet reveal that a wide range of medicinal and health properties are assigned to the genus, including as a remedy for colds, aches, allergies, indigestion, and respiratory issues. There are claims that it can boost the immune system. Some studies suggest that not only does Sideritis prevent and treat Alzheimer's disease but it also can forestall osteoporosis.

In 2011, the Journal of Ethnopharmacology published findings that Sideritis species were shown to have anti-microbial, anti-inflammatory, antioxidant, and antispasmodic properties. A 2012 publication of the Journal of Physiology and Pharmacology noted that extracts made from Sideritis helped lower blood pressure levels while helping blood vessels to relax. You may have heard of Sideritis in one of its common medicinal forms: Greek Mountain Tea, Shephard's Tea, or just plain old Mountain Tea.

Miraculous medicinal claims aside, the Cyprus ironwort is a spectacular-looking plant. When not flowering, it is a mound of soft furry gray green leaves that grows to about one foot tall and wide, and looks very similar to lamb's ear (Stachys). It blooms, in the summer, by putting out contrasting chartreuse flower stems which rise another 12-18 inches above the leaves, and carry cuplike yellow flowers. Unfortunately, this hardy beauty is listed as “vulnerable” in its native habitat under the International Union for Conservation of Nature, due to development, wildfires, mining, and other environmental stressors.

You can find Cyprus ironwort and many of the plants featured in the Dry Garden at local nurseries which specialize in California and Mediterranean natives. These plants epitomize the premise upon which the Master Gardener Demonstration Garden is based: The New California Garden: Beautiful; Sustainable; Functional. And no additional water required!

Note: For more information about the Master Gardener Program and the Demonstration Garden, please visit http://ucanr.edu/sites/bcmg/ . Garden questions can be directed to the Hotline at 530-538-7201.

 

Plants in the Dry Garden at the Master Gardeners Demonstration Garden at Patrick Ranch

Genus	Species	Common Name
Artemesia	schmidtiana	Silvermound, wormwort
Helianthus	maximilianii	Maximilian sunflower
Helichrysum		Strawberries and cream
Iris	douglasiana	Douglas iris
Melianthus	major	Honey bush
Muhlenbergia	rigens	Deer grass
Phlomis	fruticosa	Jerusalem sage
Phlomis	russeliana	Jerusalem sage
Phlomis	purpurea	Purple phlomis
Phlomis	samia	Greek Jerusalem sage
Romneya	coulteri	Coulter's Matalija Poppy, California tree poppy
Salvia	canariensis	Canary Island sage
Salvia	spathacea	Hummingbird sage, pitcher sage
Santolina	chamaecyparissus	Lavender cotton
Santolina	pinnata	Rosemary leaved lavender cotton
Scutellaria	suffretescens	Mexican skullcap, pink Texas skullcap
Stipa	gigantea	Giant feather grass
Teucrium	chamaedrys	Wall germander
Teucrium	fruticans	Bush germander
Trichostema	lanatum	Wooly blue curls