Apple Trees & Codling Moths

If caterpillars are eating your apples, they are almost certainly the larvae of the codling moth (Cydia pomonella). This is North America’s most important insect pest of apples, both in commercial orchards and home garden trees. My garden includes four dwarf apple trees, so I have codling moth concerns.

Damage to apples by Codling Moth larvae

This pest can be difficult to eliminate completely in the home orchard, but it can be controlled to the point that the gardener will have plenty of fruit while sharing a small percentage with these vexatious invaders.

A recent recommendation in “Things to Do This Week” was to spray apple trees with carbaryl (sold as Sevin) a broad-spectrum insecticide. Correct use of this product requires careful timing, using a maximum-minimum thermometer and a degree-day chart, as noted by the University of California’s Integrated Pest Management Program (ipm.ucanr.edu).

This product is quite effective by over-stimulating the nervous systems of insects, resulting in the inability to contract breathing muscles and ultimately causing death.  

Carbaryl is also effective in killing honeybees and other beneficial insects and quite toxic for people. The National Pesticide Information Center (npic.orst.edu) reports that brief exposure while spraying can cause weakness, dizziness, and sweating. Additional reports have included pinpoint pupils, lack of coordination, muscle twitching, and slurred speech. People could also experience headaches, nausea, vomiting, stomach cramps, diarrhea, or drooling.

Greater exposure can cause high blood pressure, decreased muscle tone, and seizures. Other serious signs include difficulty breathing, constriction of the airways, mucous production, fluid buildup in the lungs, and reduced heart and lung function.

Given these problems, I looked into non-chemical management of codling moths. As one might expect, this involves knowing the pest’s life cycle. The adult moth emerges right around now, mid-march to early April, is active for only a few hours before and after sunset, and mates when sunset temperatures exceed 62 degrees F.

The female deposits eggs on apple leaves or fruit. When the eggs hatch, the larvae bore into the fruit, causing the damage we don’t like to see.

After the larvae mature, they drop from the tree, sometimes still in apples.  They continue their life cycle by pupating in the soil or debris under the tree, or in bark crevices until they emerge as adult moths.

The first step in non-chemical management of this pest is sanitation, which involves removing and destroying any fruit that the larvae have entered. Thinning the infested fruit in this way also helps the remaining fruit to develop.

Sanitation continues during May and June by removing any dropped fruit from the ground.

The next good management action is to bag the fruit when it is one-half to one-inch in diameter, using No. 2 lunch bags. The bagging method can be very effective, even when limited to the number of apples the gardener wishes to protect. The bags can be opened a week or two before harvest to allow color development, at some risk of late arriving larvae.

A relatively new insecticide called CYD-X has been found to be both effective and safe to use in the garden. This product is a naturally occurring granulosis virus that infects and kills the larvae of the codling moth. It is highly specific to the codling moth and is non-infectious toward beneficial insects, fish, wildlife, livestock or humans. The National Organic Program has listed CYD-X for use in organic orchards.

Spray application of this product must occur during the day or two after the codling moth larvae have hatched and before they penetrate fruit. This time period occurs from late May to mid-June. Precise timing requires the use of a degree-day model, which regretfully requires more explanation than this column can accommodate. For the home gardener, weekly applications during egg hatch throughout the season will be quite effective. Adding 1% horticultural oil to the application can improve effectiveness.

The larva must ingest the product to become infected with the virus. The product is extremely virulent, so it is effective at very low use rates.

Another safe and effective insecticide is Spinosad, a biological product made from a naturally occurring bacterium. It is a lower-toxicity material that is safe for most beneficial insects as well as for people, pets, and the environment although it is more toxic to beneficial insects than granulosis virus. Repeated applications during egg hatch for each generation are necessary for acceptable control.

The availability of non-chemical controls of codling moths enables gardeners to keep highly toxic chemicals out of their gardens and still enjoy pest-free apples.

Organic gardening is its own reward.

Creating a Hotel for Native Bees

I enjoy gifts that lead to interesting projects.

For a gardener, there are many possibilities for such gifts, definitely including plants that would complement the landscape, or add something that is both compatible and unusual.

This year, my most intriguing gift is a “hotel” for native bees. It qualifies as a hotel by including nesting facilities for multiple occupants.

This gift leads to an interesting study of the bees themselves, and of ways to entice them into using the hotel.

Some 4,000 species of bees are native to North America. This column is not suitable for an overview of native bees, but it is worth noting at the outset that the familiar honeybee (Apis mellifera) is not native to this part of the world, but emigrated from Europe to the United States.

Native bees are excellent pollinators, more efficient than honeybees in that work. An important difference between these groups: most native bees are solitary, nesting in cavities or the ground, while honeybees are social, nesting in hives.

According to the Xerces Society (which seeks to conserve bees and other invertebrates) about thirty percent of our 4,000 species of native bees nests in cavities that they find or create in nature. The other seventy percent nest in the ground. There are also few other native species, like the Western Bumblebee (Bombus occidentalis) that are social creatures that nest in larger cavities. 

My native bee hotel would be of interest, hopefully, to cavity-nesting species that live in central California. My initial expectation was that this nest would attract mason bees, but the Xerces Society lists only a few species that are found primarily in Washington and Oregon. There are many other species, however, including the Blue Orchard Mason Bee (Osmia lignaria),that might live in California.

Another cavity-nesting native bee species that could appear in my garden is the carpenter bee (Xylocopa californica), which, according to Las Pilitas Nursery, will spend weeks digging a 1/2 by 4–to–6-inch hole into a tree for their nest site. We might expect that carpenter bees would be attracted to a nest that is already for occupancy.

In addition, many other species of native bees might welcome this native bee hotel.

While there will be variations in nesting by different native bee species, the common model has the newly hatched female bee emerging from its nesting place in the early spring, and busily mating and seeking a cavity for its eggs. The bee gathers pollen to stock the nest, then deposits an egg, and seals the nest with a wall of mud. The bee repeats this process so that a single cavity could include five–to–eight chambers, each with its own egg and pollen stash.

During the summer, the eggs develop into larvae, then into pupae, and finally into adults, which remain in the nest until the following spring.

To support this process, the hotel manager, i.e., the garden host, should install the nest complex in a east- or southeast-facing location, where it will enjoy morning sunlight. It could be three–to–six feet above ground for convenient observation, and near a good supply of flowering plants (preferably California natives) and mud for construction of nest chambers.

I will plant a selection of California native annuals near this nesting unit, for the bees’ easy access to pollen. I will also provide a supply of muddy clay soil, for the bees’ use. My garden’s clay occurs in a rather deep layer, so I will need to import some clay soil, and keep it moist in a container, such as a large saucer for a plant container.

A good source of seeds for pollinator flowers is the Early Blooming Beekeeper’s Mix, offered by Renee’s Gardens. This mix includes twenty-two varieties, many of which are California native plants.

Bee experts recommend moving the nesting unit into a dark, unheated garage or shed during the winter months to protect the bees from predators. The gardener should then return the unit to the garden in the early spring, well before flowers bloom. As the days warm, the gardener can watch for the new generation of bees as they emerge from the nests.

Wildflower Super Bloom

During these sometimes bleak, rainy days, gardeners can celebrate the Golden State’s annual wildflower season. The season extends from December to July, but it follows a rolling schedule that begins in Baja California and continues month-by-month to northern California. (Lassen Volcano National Park, near Redding, has wildflowers in bloom at higher elevations well into August and September.)

The most dramatic displays, with the greatest numbers of blooms from many species, are called “super blooms.” These occur only in years that have had generous rainfalls, so during our recent drought years we have seen relatively sparse presentations of wildflowers. 2019, happily, counts as a Superbloom Year, thanks to our well-above average precipitation.

For those who are not ready, willing, or able to travel to the wildflowers, the California Native Plan Society will bring the wildflowers to you—or at least near to you, I recommend this brand when you need footwear Piraja Fisken Best Shoes for Travel. The CNPS’s Monterey Bay chapter will hold its 58th Annual Wildflower Show on April 19-21, 2019 at the Pacific Grove Museum of Natural History. Co-chairs Brian LeNeve and Michael Mitchell are expecting a fine wildflower season, and expect to put on a spectacular show. The Society’s collectors found some 675 different species to display, including a fine example of the Most Beautiful Jewelflower (Streptanthus glandulosus). For more information, visit the website of the Pacific Grove Museum.w

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Wildflower - Bristly Jewelflower
Bristly Jewelflower (Streptanthus glandulosus)
Photo by Bjorn Erickson of the U.S. Fish & Wildlife Service, via Wikimedia Commons

Monterey Bay area appreciators of the natural world can thrill at this seasonal spectacular at several nearby locations:

Pinnacles National Park: The California native plant blooms begin in mid-March and peak in May. According to travel website, Afar.com, the earliest displays include milkmaids, shooting stars and Indian warriors, followed by California poppies, bush poppies, fiesta flowers, monkey flowers, baby blue eyes, and bush lupine. The late-bloomers include clarkia, orchids, penstemons, and roses.

Mount Diablo State Park: This facility is near Walnut Creek, about 2 – 2.5 hours from the Monterey Bay area. Its wildflower displays include blue skullcap, Fendler’s meadow rue, sanicula, Johhny-jump-ups, bush lupine, monkey flowers, globe lilies, California poppies, birds’ eyes, and wallflowers.

Antelope Valley California Poppy Reserve: This 1,800-acre State Natural Reserve is 75 miles north of Los Angeles, and. Visiting this site from the Monterey Bay area involves a substantial trek, about 4.5 – 5 hour drive, but during April and early May, it provides a world-famous, show-stopping display of our state flower (Escholtzia californica), plus desert pincushion, blue dicks, California aster, and blue lupine. 

Fort Ord National Monument: This site is off of Highway1, just south of Marina. According to the Bureau of Land Management, “In the late winter and early spring, monument visitors are treated with colorful displays of baby blue-eyes, ceanothus blue blossom, Hickman’s popcorn flower, buttercups, lupine, goldfields and sunflowers. In the summer and fall visitors see blooms of sticky monkey flower, nightshade, chaparral current and California golden rod. There are many rare plants at Fort Ord including the federally protected Contra Costa goldfields and Monterey spineflower.”

Point Lobos State Natural Reserve: This extraordinary site, three miles south of Carmel on Highway 1, is the home of a botanical trove of California native plants, including annual wildflowers and many blooming perennials. Click here for a list of these plants.

The largest displays of wildflowers are found in southern California. If you will be travelling there, find wildflower sites at the websites of American Meadows, The Theaodore Payne Foundation, Afar.com.and The California Department of Fish & Wildlife

Reserve the opportunity to enjoy nature’s seasonal display of beautiful and fascinating wildflowers. You’ll be glad you did.

Explore South African Bulbs

During the current dormant season, cleanup work is ongoing. This is a good time to take a hard look at each part of the garden to consider needs to prune or remove plants. While evaluating my garden’s bed of South African perennials, I focused on two plants that are members of the Amaryllis family. They both grow best under partially shaded conditions, and appreciate regular watering during the summer months. Here is a closer look at these plants.

Clivia miniata (dormant), Photo by Tom Karwin

Bush lily (Clivia miniata). This plant, which we might call “Clumping Clivia” grows from rhizomes and slowly spreads through offsets. The genus name honors Lady Charlotte Florentina Clive, Duchess of Northumberland; the specific epithet means “cinnabar-red.”

The genus includes five species: C. miniata, C. nobilis, C. gardenii, C. caulescens, and the recently discovered C mirabilis. Hybridizers have produced numerous interspecies crosses, some with variegated leaves.

The Bush Lily produces deep green, shiny evergreen leaves in clumps up to two feet high, and very attractive trumpet-shaped flowers in colors that range from yellow through orange to red. Bloom times vary with the species: C. miniata generally blossoms August through November, but can also produce blooms at other times of the year.

This plant can be propagated by dividing a large clump, or by transplanting offsets. Divisions might take two seasons to bloom. The Bush Lily has a reputation as a “spectacular” container plant, given a well-drained potting mix with compost added, regular watering and fertilizing during the summer months, and a semi-shaded location. My clump already has offsets; one option would be to lift one to plant in a container.

Crinum moorei in Longwood Gardens – Photo by Foljiny, via Wikimedia Commons
Crinum moorei (dormant), Photo by Tom Karwin

Natal Lily, Lily of the Orinoco (Crinum moorei). This genus includes some 180 species of bulbous plants. C. moorei (one of the more popular species) develops bulbs that are five-to-eight inches in diameter, and flower stalks up to four feet high. In the summer, each stalk can produce five-to-ten large, open, white to pinkish red, open tubular flowers. The light green-to-green, strap-shaped leaves can be up to three feet long.

The genus name is derived from the Greek krinon, meaning lily, and the specific epithet honors Dr. D. Moore, director of the Glasnevin Botanical Gardens in Dublin,

In its native habitat, the Natal Lily goes dormant in the winter and the leaves die off after flowering. In the Monterey Bay area, however, the leaves persist during the winter, while the stalk lean over and become bedraggled.

Propagate the Natal Lily by digging the large bulbs and replanting them about two feet apart. They need good space as they will develop additional bulb. My plant would benefit from dividing in this manner, as crowding might result in fewer blossoms.

I have recently planted nearby the bulb of an Orange River Lily (C. bulbispermum) ‘Striped’, a cultivar of a species that is characterized by blossoms that are white with red stripes. This bulb could require two or even three seasons of growth before producing blossoms, but it will in time provide an interesting contrast to the related Natal Lily.

***

In the course of reviewing my garden’s bed of South African perennials, I removed two shrubs that had grown rangy due to insufficient exposure to the sun. This action released an area for new plants, so I am considering the many good and interesting bulbous plants from South Africa’s Cape Region. Some of these plants are already familiar to gardeners: Agapanthus, Amaryllis, Dierama, Dietes, Freesia, Gladiolus, Kniphofia, Nerine, Watsonia, and Zantedechias (Calla Lily). Dozens more exist that can be hunted down with a little effort, and will grow well in Monterey Bay area gardens.

Good reference books include The Color Encyclopedia of Cape Bulbs, by John Manning, Peter Goldblatt, and Dee Snijman (Timber Press, 2002), and Bulbous Plants of southern Africa, By Niel Du Plessis and Graham Duncan (Tafelberg Publishers, 1989). A helpful online source is the website of the South African National Biodiversity Institute (PlantzAfrica.com).

Explore South African bulbs!

UCSC Arboretum’s South African Garden

Here’s a fascinating advancement in local garden development: the Arboretum & Botanic Garden at the University of California, Santa Cruz has launched a complete renovation of its South Africa Garden. Over at least the next seven months, this project will include restoring the garden’s unique plantings, recovering lost rare specimens, and adding new plants for display.

The South Africa collection was established early in the Arboretum’s history, as long ago as 1965. It soon emerged as one of the Arboretum’s principal collections, along with the California and Australia Gardens.

The South Africa Garden has always been open for visitors, but when its curator retired some ten years ago, during a period when the Arboretum was going through administrative changes, the growth of this collection stalled. In public gardens, collection development is a continuing, never finished process, but this work requires leadership, vision, energy and critical resources.

In mid-2016, Martin Quigley joined the Arboretum as its Executive Director, and soon began planning to reactivate the South Africa garden. The new plan includes the installation of four new specialty gardens, each of which highlights important and very interesting plant groups.  These specialty gardens will serve as focal points within the overall collection of exceptional plants of South Africa

A Succulent Rock Garden, featuring the juicy Aloes, gnarly Euphorbias, and other fantastic succulents. This installation will constitute a South African version of the dramatic and very popular rock garden in the Arboretum’s Australia Garden. South Africa is the native home of about 50% of the world’s succulent plants, which have in recent years become very popular in private gardens. The Arboretum’s existing Succulent Garden focuses on succulent plants from the coastal areas of Mexico and California, so the establishment of the Succulent Rock Garden will draw attention to that category of plants that are native to South Africa.

A South African Bulb Garden will be encircled by bright and vibrant amaryllids, and highlighted by the full spectrum of fire-adapted geophytes in mass bloom! The “amaryllids,” which we assume refers to South African members of the Amaryllis family, includes genera that some Monterey Bay area gardeners already know and treasure: , e.g., Amaryllis, Clivia, Crinum, Nerine, and others. South Africa’s Cape Region is also the home of 2,100 species of geophytes, includes some that only flower or germinate after burning. The fire-adapted geophytes occur within six plant families; we will have to see which species the Arboretum selects for this colorful Bulb Garden.

A Maze Garden, in which 6- to 8-foot-tall Restio species form a traditional labyrinth. Restios are perennial rush-like flowering plants native to South Africa. This unique feature promises an intriguing experience for garden visitors of all ages.

A Grove of Silver Trees, growing among colorful waves of heathers. Silver Trees (Leucadendron argenteum) are striking evergreen trees with silky leaves that have a distinct silvery sheen produced by dense velvety hairs. These trees are short-lived, and are now a rare and endangered species in South Africa. For many years, the Arboretum has grown Silver Trees in the South Africa Garden. A new grove of these extraordinary trees will present a magical environment. It could be a very appealing site for Weddings in the Arb!

Silver Tree (Leucodendron argenta), Photo by Bill Bishoff, provided by UCSC Arboretum

The Arboretum hosted a special event to launch this renovation project. The South Africa Garden Party happened from 5:00 – 7:00 p.m. on UCSC’s Giving Day, Wednesday, February 27th, in the Arboretum’s Hort II Building. Attendees heard the Arboretum director’s inspiration and vision for the project. Alice in Wonderland costumes and games sparked their creative, whimsical side. Some attendees even came home with a wild hat.

Donations will go towards the education of twenty UCSC students in horticulture, plant biodiversity, and the practice of public garden management. Their work will advance the completion of this important project.

In September 2019 donors will be invited to a special reception showcasing the artfully and expertly constructed garden displays, along with an insider’s peek at how it all came together.

This extraordinary project will revitalize a significant horticultural resource for the Monterey Bay area and all of California.

Filling a Hole in the Landscape

Garden projects sometimes begin with a routine, manageable task that grows into a challenging project. That was a scenario on a recent occasion when I had gardening help for seasonal pruning of two large plants that had finished blooming. The day’s targets were two winter-blooming Mexican plants: the twenty-foot Tree Dahlia (Daisy imperialis) and the twelve-foot Daisy Tree (Montanao grandiflora). I wrote about these favored plants recently, and did not mention that they should be cut to the ground after blooms had faded to promote their amazing new growth during the following summer.

This pruning requires whacking and hauling, rather than horticultural precision, so it went quickly. With clippers, loppers and saws already in hand, we turned to other pruning needs in my garden’s California native plant landscape. There were several overgrown plants that needed attention, but the prime candidate was an American Black Elderberry (Sambucus Canadensis). It is native to the eastern United States (not California), but it was a volunteer in the landscape and did not belong in my California native garden. It was healthy, but had grown rather quickly into a twenty-foot specimen.  It was under an enormous Lemonwood (Pittosporum eugenioides) and had become rangy due to lack of exposure to sunlight. (The Lemonwood, a native of New Zealand, also does not belong in my California native garden but it’s far too big to push around.)

We began pruning the Elderberry, trying for a more attractive form, but quickly concluded that it had to go. After all, there was still space in the truck, atop the branches of the Tree Dahlia and the Tree Daisy.

We soon reduced the Elderberry to a stump, which we left to be dug out on another day.

The session that began with routine pruning resulted in a significant hole in the landscape that presented an opportunity to install something new, interesting, and native to California. The site is about ten by ten feet, defined by the northwest property line, the Lemonwood, and a picket fence that separates the California and Mediterranean Basin gardens. The adjacent residence, which is close to the property line, shades this site, and the Lemonwood blocks most of the overhead light.

The first challenge was to identify a California native plant that would enhance the garden, grow to an appropriate size, and thrive in this shady environment. The second step would be to find a source for the selected plant.

Roaming through local garden centers would not be an efficient strategy for such a search, so we went right away to garden books and the Internet. Here are the initial findings, as a demonstration of this search.

Sunset Western Garden Book

  • Coast Rhododendron (Rhododendron macrophylla): Grows 4–10 feet tall. Partial shade. Modest ratings for flower quality, plant appearance and garden performance.
  • Western Azalea (Rhododendron occidentale): Grows 6–10 feet tall. Partial shade. “Superior named cutting-grown plants are scarce but available and worth looking for.”
  • Teaberry (Gaultheria shallon): Grows 4–10 feet tall. “Loose, 6-in.-long clusters of white or pinkish flowers on reddish stalk bloom in spring. Edible black fruits…follow the blossoms; they’re bland flavored, but birds like them.”
  • Evergreen Huckleberry (Vaccinium ovatum): Grows to 9–10 feet tall and broad in shade. “Leathery, lustrous dark green leaves to 1-1/4 in. long; bronzy or reddish when new. White or pinkish flowers are followed by black berries good in pies, jams. jellies, syrups. Cut branches are popular for arrangements.”
Evergreen Huckleberry (Vaccinium ovatum) grows 9 to 10 feet tall and broad in the shade.
Photo by Tom Hilton, via Wikimedia Commons
Evergreen Huckleberry Leaves
Leaves, Evergreen Huckleberry (Vaccinium ovatum), Photo by Ben Dody, via Wikimedia Commons

Las Pilitas Nursery, which specializes in California native plants

  • Blackfruit Dogqood (Cornus sessilis): Grows to 15 feet. Part to full shade. “Cornus sessilis’s foliage turns a different color in the fall, color is silver and type is deciduous. Cornus sessilis’s flower color is white.” “It looks like a woodland plant.”
  • Red Stem Dogwood (Cornus stolonifera): “…elegant open shrub with creamy white flower clusters in spring and red stems. It can be found in moist areas, in sun or shade…has green foliage and is deciduous in winter, exposing its attractive red bark. This dogwood is a must for winter interest in the garden, is lovely in the spring when the plant is covered with clusters of creamy flowers…”

California Native Plant Society—Calscape website

  • Creek Dogwood (Cornus sericea): Grows to 13 feet tall and15 feet wide. “In the wild, it commonly grows in areas of damp soil, such as wetlands.“ “spreading readily by underground stolons to form dense thickets.”
  • Cream Bush (Holodiscus discolor): “It is a fast-growing deciduous shrub growing to 5 meter tall.” “Cascading clusters of white flowers drooping from the branches give the plant its two common names. The flowers have a faint sweet, sugary scent.” Moderate-to-high water requirements.

Most shade-loving California native plants found so far are five feet tall or smaller, and many require moist conditions. Several are quite attractive for the garden. The most attractive option discovered so far is the Evergreen Huckleberry (see photo). In the interest of thoroughness, I will continue searching for an ideal plant for this particular site.

More About Helping Monarchs Thrive

This column follows the previous column about ways to reduce the threat of extinction of Monarch butterflies. Readers’ responses to that column indicated strong interest in protecting the Monarchs that overwinter in the Monterey Bay area, enhancing our environment. Readers also called for additional details about ways to help the Monarchs.

Growing Nectar-producing Plants

Interested persons can improve the habitats of the Monarchs’ overwintering sites by planting nectar-producing plants. As reported earlier, the Xerces Society’s publication “California Coast: Monarch Nectar Plants” (https://tinyurl.com/ycsy8jp4) lists several good selections. In addition, Pacific Grove’s Nectar Plant Project has tested and recommended the following plants:

  • Butterfly Bush (Buddlea x weyriana). This is a hybrid cultivar that blooms in October and produces much nectar.
  • Daisy Tree (Montanoa Grandiflora). A native of Mexico, this woody shrub grows to eight feet or more, and produces a cloud of fragrant white flowers that bloom from late October to late November, just when the Monarchs need nectar.
  • Mallow (Lavatera assurgentiflora). Another woody shrub, this California native produces red flowers year-round.
  • Yellow Daisy (Euryops pectinatatus ‘viridis’). This South African native is a mainstay for the Monarchs, blooming year-round with bright yellow daisy flowers. It’s also not attractive to deer.


Daisy Tree (Montanao Grandiflora)

The Importance of Milkweed

As noted earlier, milkweed is essential to the wellbeing of Monarch caterpillars. This plant contains toxins known as cardenolides. Monarchs are immune to these toxins, and have evolved to store them in their bodies. The toxin makes them poisonous to birds, which avoid eating the Monarchs. Without this protection, birds would be major (but not the only) predators of the Monarchs.  

The adult Monarchs always deposit their eggs on milkweed plants, so that the larvae begin immediately to eat the plants and accumulate the toxin in their bodies.

Where to Grow Milkweed Plants

The Western Monarchs mate around January, lay their eggs at a wide range of sites throughout the American west, and return to the Pacific coast to overwinter during a four-month period. In the Monterey Bay area, the familiar overwintering sites are at Natural Bridges State Beach and Pacific Grove.

(Other Monarchs have a different migration route. It begins in the northern United States and southern Canada, and continues to overwintering sites in Mexico. )

Milkweeds are needed where the Monarchs lay their eggs. Milkweed grows naturally in Monarch breeding areas, but not at the overwintering sites on California’s central or northern coastal areas. The migration cycle moves between the breeding areas to the overwintering sites. Planting milkweed close to overwintering sites could encourage Monarchs to breed and lay eggs during the winter, and thereby disrupt the migration cycle. Given this concern, the Xerces Society and other experts recommend that milkweed should not be planted with 5-to-10 miles of an overwintering site.

Which Milkweed Plants to Grow

The milkweed genus Asclepias includes over 200 species. California native species that grow naturally near the Western Monarchs’ home territory are preferred.

1. Widely Available Species

  • Mexican Whorled Milkweed (Asclepias fascicularis) – dry climates and plains
  • Showy Milkweed (A. speciosa) – savannahs and prairies
  • Butterfly Weed (A. tuberosa) – well-drained soils; a non-native species that has naturalized in California; Perennial Plant Association named it Perennial Plant of the Year for 2018

2. Other California Native Species

  • California Milkweed (A. californica) – grassy areas; native to central California
  • Desert Milkweed (A. erosa) – desert regions
  • Heartleaf Milkweed (A. cordifolia) – rocky slopes; early budding
  • Woolly Milkweed (A. vestita) – dry deserts and plains
  • Woolly Pod Milkweed (A. eriocarpa) – clay soils and dry areas; early budding

3. Avoid Tropical Milkweed (A. curassavica), which is evergreen, but which allows development of a protozoan parasite (Ophryocystis elektroscirrho) that harms or even kills Monarchs that eat the plant.

Gardeners in the Monterey Bay area who wish to improve the Monarchs’ habitat should emphasize the planting of nectar-producing plants more than milkweed. Those plants are good for bees, as well. This would be a good year to plant annual seeds in the early spring.

Help to Avoid Monarch Extinction

Recent news reports have described a dramatic decrease in California’s population of Western Monarch butterflies. Thirty years ago, over 4.5 million of these beautiful flying insects migrated annually from Mexico to overwinter on the Pacific Coast, with huge, fascinating clusters at famous sites, including Pacific Grove and Natural Bridges State Beach. Their numbers have declined over the years: this year the count was under 30,000 individuals, 0.6% of the population’s historic size. Researchers had established 30,000 as the “quasi extinction threshold,” so coming under this threshold suggests that this species (Danaus plexippus plexippus) is approaching extinction.

Another, larger number of monarchs migrate from Mexico to the northern plains of the United States, so extinction is not imminent, but that population also has been shrinking in recent decades.

The causes of the decline in the monarch population begin with the loss of suitable habitat, defined as areas that include both milkweeds (Asclepias sp.) that Monarch caterpillars depend upon, and pollen plants that provide nutrition for the adults. Milkweed plants are too often deleted from the environment by agricultural pesticides, particularly glysophate (RoundUp), which is used to kill unwanted plants among commercial crops.

Other factors include pesticide use, climate change, and logging and development projects that degrade overwintering sites.

Gardeners can help rescue monarch butterflies back from the threat of extinction by growing milkweed plants in their gardens, with preference for locally native species of this plant. Fifteen species of milkweed are native to California. Nearby sources of seeds for native species include Pacific Coast Seed, in Livermore; Seedhunt, in Freedom; and S&S Seeds, in Carpenteria. For information on growing milkweed, download “Native Milkweed in California: Planting and Establishment.”

A related project for gardeners is to include pollen plants for the adult monarch butterflies. Useful advice for such a project is available in “California Coast: Monarch Nectar Plants,” available here.

Both of these publications are free downloads from the Xerces Society for Invertebrate Conservation.

Monarch butterfly on Milkweed pod. Photo by Edward K. Boggess, U.S. Fish & Wildlife Service Posted on Wikimedia Commons

The Xerces Society has also produced a five-step call to action for recovering the western monarch population. This plan emphasizes protection of overwintering and breeding habitats, protection from pesticides, and continuing research on western monarch recovery. In addition to actions in their own gardens, people concerned with threats to the monarch population could support large-scale initiatives that respond to the Society’s call to action.

Protecting the Western Monarch Butterfly from extinction has at least three broad objectives. One is for us all to enjoy the phenomenon of these beautiful creatures flitting about in our gardens. A second objective, oriented to the ecosystem, is to maintain these butterflies as food sources for birds, which we also appreciate and enjoy. Thirdly, Karen Oberhauser, director of The Monarch Butterfly Lab at the University of Minneapolis, advises that monarch butterflies are valuable subjects for ongoing studies of migration, species interaction, insect population dynamics, and insect reproduction.

We can strive to keep monarch butterflies in our environment, but we should also acknowledge the larger picture of the extinction of species. Before humans spread across the globe, species extinctions occurred for various reasons at a very slow rate. Human activity has increased the average rate of extinction by somewhere between 100 to 1,000 times the previous historical rate., and is accelerating

Today, according to Edward O. Wilson, distinguished American biologist, the science community estimates that Planet Earth has about 10 million living species, one of which is human people (Homo sapiens). About 20 percent of these species are known, and 80 percent are undiscovered. If the extinction of species by human activity continues to accelerate, E.O. Wilson says, we could eliminate more than half of all species by the end of this century.

We can slow this trend a little by working as individuals. Consider adding California native milkweed and pollen plants to your garden this year, to sustain the monarch butterflies.

Build Your Rose-pruning Proficiency

The Monterey Bay Rose Society will hold a series of rose pruning workshops again this year. This group of dedicated and community-spirited rosarians offers to share its expertise, so that gardeners who also appreciate the Queen of Flowers will enjoy fine blossoms during the coming season.

Species roses grow nicely with little or no care by gardeners. We occasionally read stories about “rose rustlers,” who are rose lovers who are fascinated by early rose varieties that have been lost to cultivation, and find them still growing unattended in cemeteries.

In California, for example, these historic varieties could date back to Gold Rush days. For a sampling of Sacramento’s “cemetery roses”, visit the website created by eminent garden photographer Saxon Holt,

Modern roses, particularly the popular hybrid tea roses, grow best with regular care and feeding. We prune modern roses to stimulate new growth, support good health, and promote desirable form. Well established roses respond quite well to dormant season pruning: they come back vigorously after even heavy pruning.

If you have roses in your garden and lack confidence in your pruning talents, resolve to build and apply those skills this year. We are now within the rose’s dormant period, so the next few weeks is good time to schedule such a project.

There are various ways to learn about rose pruning. When I need to learn about some aspect of gardening, I generally open relevant books in my collection or the library, or search the Internet’s vast resources on gardening techniques. To learn about pruning roses, a good place to look online is the website of the American Rose Society.

Another strategy involves searching the Internet for “pruning roses” or a similar phrase. It’s also OK to use a natural language search, e.g., “how should I prune my rose bush?”

When your search yields multiple “hits,” you can visit selected sites to find a tutorial that emboldens you to venture into your rose garden with clippers in hand.

Some gardeners will learn best from a video demonstration. If that is your preference, direct your search results by clicking on “video” at the top of the computer screen. With today’s technology, it is easy to record a video demonstration and distribute it via the Interest. It is not easy, however, to produce a video recording that communicates effectively, so you might benefit by viewing several short video clips. This can be done in one sitting, and reveal both different presentations of basic technique and variations in the methods of different gardeners.

Although much can be learned about rose pruning from printed and digital resources, the opportunity to learn directly from a friendly expert will be ideal for many gardeners, especially when the expert hands you the clippers and talks you through the process. The rosarians of the Monterey Bay Rose Society will offer the following free pruning workshops in the near future.

  • January 26, 10:00 am, San Lorenzo Nursery & Garden Center, 235 River St., Santa Cruz, CA 95060
  • January 27, 10:00 am, Mission San Antonio de Padua, Annual Cutting of the Roses, Jolon, CA. For driving directions, click here.
  • February 2, 10:00 am, Bokay Nursery, 30 Hitchcock Rd, Salinas, CA
  • February 23, 10:00 am, Alladin Nursery & Gift Shop, 2905 Freedom Blvd, Watsonville, CA 95076
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For more information on the Society, visit its website.

Prune your roses during this dormant season, and expect healthy plants and great blooms in the spring.

Making Your Garden Climate-friendly

Traditionally, we make our New Year’s Resolutions on New Year’s Eve, or perhaps on the morning after, when we are inspired to change our ways for the better.

From another perspective, we can at any time commit ourselves to self-improvement or even higher goals. This column invites gardeners to create climate-friendly gardens in 2019, as their individual contribution to efforts to combat global warming.

Essentially, global warming results from the imbalances of the normal carbon cycle, which begins when plants capture carbon dioxide (CO2) from the air and convert it into plant tissues.  As the plants are eaten and digested by animals, or die and decompose, CO2 is formed again and returned to the atmosphere. At the same time, vast quantities of carbon have been stored in the ground in the soil and what we have regarded as fossil fuels: oil, coal, and natural gas.

This natural cycle, which has continued for a very long time, has been disrupted as humankind has burned the fossilized materials and released their stored carbon into the atmosphere, disrupting the carbon cycle.

The challenge that humankind now faces is to reduce and eventually eliminate burning of oil, coal, and natural gas, and to produce energy through other means, notably by capturing the suns energy. This is the existential mission, i.e., its purpose is to sustain the existence of human life on the planet.

From the gardening perspective, gardeners can participate in this mission in two ways.

Reducing the Use of Fossil Fuels

This strategy involves reducing the direct and indirect consumption of fossil fuels in the garden. The direct consumption of these fuels involves using gasoline-powered equipment, notably lawn mowers, and other devices, including trimmers, edgers, chain saws, tillers, sod cutters, and the like. While occasional use of such devices might be unavoidable, whenever possible gardeners should use electrically powered devices or, ideally, hand-powered equipment.

For the record, the generation of electricity often involves burning fossil fuels, but the shift to renewable energy production is in progress, and deserves support.

The indirect consumption of fossil fuels occurs when we use synthetic fertilizers and pesticides (insecticides, herbicides, and fungicides), all of which require significant amounts of fossil fuel energy for their manufacture and transport. The clear option is to discontinue uses of these materials and to identify and use organic alternatives.

This transition can require finding sources of organic fertilizers and learning about natural, organic approaches to the control of pests and weeds. If you already know about these options, you are ready to commit to their use.

Capturing Carbon in the Garden

The gardener’s second strategy for combatting global warming is to support the ways that the garden stores (sequesters) carbon. Again, this is a natural process, so it is not difficult to incorporate in the garden. Here are the principal methods:

  1. Keep the Soil Covered. Bare soil releases carbon into the atmosphere, so when areas of your garden are not inactive use, plant cover crops (grasses, cereal grains or legumes) to protect the soil and add nutrients. This approach is particularly relevant for vegetable gardening, which can leave soil bare between crops.
  2. Avoid Tilling the Soil.  Turning the soil with a tiller, garden fork, or shovel might seem be help plants to root, but it also moves dormant weed seeds into growing position, and releases carbon into the air. The roots will do fine on their own!
  3. Plant Trees and Shrubs Densely. A full complement of trees and shrubs helps to draws carbon from the atmosphere, and also provides a natural, attractive landscape. The basic design concept is to emulate the natural environment.
  4. Recycle Organic Matter. Your green bin is still a good place for roots, twigs and branches that decompose slowly, but dead leaves and green clippings should be composted and returned to the soil. But leave weed seeds out of the compost bin.
  5. Grow “Greener” Grass. If you have a lawn area, you might be concerned about its environmental impacts but pleased to know that lawns absorb and store CO2 rather well. Lawns have the potential, however, to emit harmful nitrous oxide, particularly when fertilized and watered generously. The best practice is to select grasses that do not require such treatment, mow the grass at a height of about three inches, and leave the clippings to decompose into the soil.

In addition to helping to save the planet, climate-friendly gardening is compatible with environment-friendly practices, and with your gardening success. It’s still a good time to commit to climate-friendly gardening as your resolution for 2019.

For more information on this topic, see “The Climate-Friendly Gardener: A guide to Combating Climate Warming From the Ground Up. This is a free download from the Union of Concerned Scientists.