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

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. 

Creating a Garden Map

Creating a record of the plants in your garden yields several benefits. A “garden record” includes two essential components: the name, photo and basic cultivation notes for each plant, and an indication of each plant’s location in the garden.

A more elaborate plant record could include extensive plant info that reflects the gardener’s interests. Examples include purchase details (when, where, cost); native region; and landscaping ideas. The record could be extended further with notes on the plant’s development over time, including bloom times, pruning, propagation, fertilization, etc.

Such details, while relevant, are the territory of professional growers and very zealous gardeners.

The minimalist approach to a garden record involves simply inserting a plant tag in the soil next to the plant. A respectable tag from the nursery provides the plant’s botanical and common names, plus a phrase about its mature size and growth needs. Placing the tag in the soil marks its spot in the garden. This method, although popular, has notable shortcomings: sparse information, ephemeral mark of location, and plastic intrusion into the natural setting.

Plant tags are best used for temporary reference, during the preparation of a better garden record.

After considering those extreme forms, let us return to the fundamental model of the plant record.

Plant Information

Compiling information on an individual plant can be accomplished most easily and quickly with an Internet search, using the plant’s botanical name, or, if necessary, its common name. This information should be available on the plant tag.

The first search should be the website of the nursery that grew the plant. The nursery’s name could be read from the plant tag, or provided by garden center that sold the plant.

Other good sources include San Marcos Growers in Santa Barbara. SMG grows many plants and supplies them to garden centers. Their website (includes a fine database of plants that they grow —or used to grow— with photos and detailed descriptions, cultivation suggestions, and notes on the plant’s discovery or hybridization.

More good online resources include Wikipedia for plant information and Wikimedia Commons for plant photographs.

Other websites with useful plant information could be discovered through a botanical name search.

After locating basic plant information, good practice involves developing a database of plants in your own garden. This could be accomplished on paper or in digital form, i.e., as a computer file. Organize the plant under discrete planting beds or areas of the garden.

Garden Map

The second component of the garden record is a map showing the location of each plant in the database. Plant locations could be documented with notes within the plant description, but a graphical map would be a more useful reference for monitoring plant growth and developing the landscape development.

The garden map need not serve as an artistic triumph or an exercise in precise engineering, but it should amount to a scale drawing of the garden area. For a garden on a standard lot with a typical complement of plants, a map of the entire garden could be sufficient. For larger gardens, or those with many plants, a series of maps representing areas of the garden would support notations indicating plant locations.

On the map, represent each plant with its name, or a numeral linked to the plant record, or a numeral linked to symbol. The symbol could be a circle of appropriate size, or, for the artistically inclined, a simple drawing that suggests the size and form of the plant.

Again, primary purpose of the garden map is to document plant locations, rather than to create a work of art.

The map must be editable, so that it could be updated to reflect additions, deletions, and relocations of plants. Working in pencil could be most appropriate.

A garden map also could be created and maintained as a digital file. This method involves the use of computer graphic software, either a general purpose or garden-mapping application. This column cannot include an overview of garden mapping software, but, generally, the garden-mapping software that is currently available is intended for edible gardens in which plants grow in rows. Such software could be helpful for planning and describing traditional vegetable gardens, but is not suitable for ornamental gardens, or for edible gardens that are designed for aesthetic effect, including those that creatively combine edibles and ornamentals.

Graphic design software with the functionality needed to represent irregularly shaped planting beds is certainly available, but tends to require significant expense and skill.

Avid gardeners can develop plant information and garden maps to create garden records of substantial value in developing and maintaining the garden. Good practice suggests adopting readily accomplished formats, rather than aspiring to high standards that are unlikely to be achieved or maintained. The first priority should be to create the garden record as a practical tool for planning, developing and maintaining your garden.

The rainy season is a good time to pursue your garden record project!

Plants Preferred by Other Insects

In a recent column, we described the first report of the Royal Horticultural Society’s “Plants for Bugs” study, which focused on Pollinators. In this column, we’ll look at the second report of this study, “Gardens as Habitats for Plant-Dwelling Invertebrates” (August 2017), which is about insects and invertebrates that live in our gardens, and the plants they love.

Let’s first review the related taxonomic issues.

Gardeners should appreciate the difference between “bugs” and “insects.” The title of the RHS study uses “bugs” to refer informally to a large and diverse group of invertebrates. To be precise, true bugs are members of the order Hemiptera, which is within the class Insecta. There are some 50,000 to 80,000 species of true bugs, all of which have sucking mouthparts. Examples of true bugs include cicadas, aphids, planthoppers, leafhoppers, and shield bugs. By the way, none of the true bugs are pollinators.  

The Insecta is a class within the phylum Arthropoda, which includes 6 to 10 million species, all of which are hexapod (six-legged) invertebrates.

To put the true bugs in perspective, they represent only a tiny fraction of the Insecta.

Returning now to the RHS study, the first report addressed garden insects that are Pollinators, which include bees, butterflies, and a few other insects.

The second report addresses other significant categories of garden insects, which include these groups:

  • Herbivores. Invertebrates that feed on living plants, using chewing mouthparts (e.g., caterpillars) or sucking mouthparts (aphids are a familiar example).  
  • Predators. These are invertebrates that eat other invertebrates. These include lacewings, beetles, e.g., ladybirds, some true bugs, spiders, and parasitoid wasps, which kill their hosts.
  • Omnivores. These invertebrates feed on both plants and other invertebrates. This group includes the harvestman (a spider relative), earwigs, and aphids.
  • Detritivores. Invertebrates that feed on decomposing organic matter. Examples include springtails, woodlice, and some beetles.
Common Lacewing (Chrysopa species) photo by JJ Harrison, shared via Wikimedia Commons

These groups, along with the Pollinators featured in the first report of the RHS study, constitute a vital component of the garden’s balanced ecosystem. In addition to breaking down dead plant material, these plant-dwelling invertebrates provide food for other wildlife, including birds, reptiles, and small mammals.

In their four-year Plants for Bugs study, the RHS scientists used suction samplers to collect about 18,000 of plant-dwelling invertebrates. Their samples included 18% Herbivores, 3% Omnivores, 18% Predators, and 61% Detritivores. They also collected about 4,700 uncategorized invertebrates.

They recorded these collections of invertebrates separately from plants that were native to three different areas: the United Kingdom (called ”natives”), other areas in the Northern Hemisphere (“near natives”, and Southern Hemisphere (“exotics”).

As they found with Pollinators, the scientists found that the native plants supported the largest numbers of the plant-dwelling invertebrates. By comparison with the native plants, the near-native plants supported about 10% fewer invertebrates, and the exotic plants supported 20% fewer.

Overall, these observations indicated that native plants are most important in supporting these groups of invertebrates, and the near-native and exotic plants also provide effective support at somewhat reduced levels.

The study concluded that gardens should emphasize native plants, but could include near-native and exotic plants as well. The most important consideration was to develop a dense planting scheme so that the garden could support all kinds of plant-dwelling invertebrates as part of a balanced ecosystem.

Exotic plants are important to include in the garden for Pollinators because Southern Hemisphere plants often bloom during months when Northern Hemisphere plants are dormant, and thus provide Pollinators with food sources for a longer period of the year.

Although this study was conducted in England, its findings could apply reasonably also to gardens of the Monterey Bay area. With that interpretation, we would treat California native plants as the “natives,” plants from the Mediterranean climate areas as “near natives,” and any other plants as “exotics.”

These two studies support the usual assessment that native plants are most supportive of local plant-dwelling invertebrates, while showing that near-native and exotic plants also provide effective supports for the garden’s ecosystem.

These findings might apply as well to local birds, reptiles and mammals, but demonstrating those relationships would require another study. For example, while berry-producing shrubs provide natural food for birds, separate counts of bird visits to native, near-native, and exotic berry-producing shrubs might yield interesting results.

That would be a very challenging assignment!

Plants Preferred by Pollinators

When planning their gardens, many gardeners recognize the relationships between their plants and local wildlife. This ecological perspective has gardening implications for each of several categories of wildlife: birds, mammals, reptiles, and various invertebrates.

An overarching concept for this ecological perspective is the food chain. Insects are low on the food chain, so selecting plants according to the needs and preferences of insects has impacts on the higher levels of the chain. As a basic example, plants that attract insects to the garden increase the food source for birds and reptiles, and an increase in the numbers of birds and reptiles provides food for carnivores.

Gardeners often want to grow flowering plants that attract bees, butterflies, and other pollinators. Those gardeners might intend primarily to support plant pollination and garden aesthetics (butterflies always delight the eye), but their plant selection also supports the food chain. 

As we develop our garden and select plants from this ecological perspective, we might favor plants that are native to our local environment. The rationale for preferring native plants reflects an assumption that the insects and other wildlife in our gardens know and prefer plants that they have encountered throughout their lives, and the lives of their preceding generations. Surely, wild creatures communicate survival knowledge to their offspring at least by demonstration.

For such reasons, I have favored native plants because of their presumed appeal to local wildlife, in addition to the compatibility of native plants with native soil, climate, and plant communities. The logical application to this view is for the gardener to fill the garden with native plants.

This approach to landscaping succeeds. We are not here to negate gardening in the Monterey Bay area with California native plants.

I have become aware, however, of another layer of thought to consider.

In a recent issue of Horticulture magazine, entomologist Eric Grissell described a wildlife gardening study, “Plants for Bugs,” conducted by England’s Royal Horticultural Society.

I visited the project’s website to learn about this project. Its first bulletin for gardeners is titled “Gardens as Habitats for Pollinators” (August 2015). This column addresses the study’s methods and findings related to pollinators.

Honey bee (Apis mellifera) pollinates creeping thistle  photo by Ivan Leidus,
shared via Wikimedia Common

The study’s approach was to observe the numbers of times pollinating insects land on flowers of plants with each of three different origins: United Kingdom natives; other Northern hemisphere natives, i.e., plants from regions similar to the UK; and Southern hemisphere natives, i.e., plants from climates and habitats that are different from the UK.

The study’s original recommendations are oriented to the United Kingdom, but they could be applied reasonably to other gardening environs. Accordingly, I have modified the wording of these statements to relate them to gardening in the Monterey Bay area.

  1. Gardeners should plant a mix of flowering plants from different countries and regions;
  2. Plant selection should emphasize plants that are native to California’s central coast, or to the Mediterranean climate areas;
  3. Regardless of plant origins, the more flowers the garden can offer throughout the year, the greater number of pollinators it will attract and support.

Plants that are native to the garden area are still important, but gardens serve pollinators best when they have large numbers of flowers and a long flowering season, regardless of the origins of the plants.

In a future column, we’ll review this project’s second bulletin, “Gardens as Habitats for Plant-Dwelling Invertebrates” (August 2017).

Assessing a Neglected Shrub

A situation that could arise in any garden, including your garden: the gardener becomes aware of a shrub that has been neglected and that has outgrown its space and become rather misshapen. In addition, the gardener has lost track of the shrub’s name and can’t locate cultivation notes on the Internet.

I recently had such a challenge in my garden’s Australian bed. While I was not paying attention, a shrub grew to about five feet high and eight feet wide, and began crowding adjacent plants. In addition, it had been produces leaves and flowers at the ends of its branches, so that the interior of the plant consisted of bare branches. Some of those had died back so that lifeless tips of branches appeared among the greenery.

The plant had been in place for a few years, and I could not recall its name.

For the past several years, when I added a plant to the garden, I searched the Internet for a photo, a verbal description, cultivation notes, and any other information of interest, and compiled it into a one-page “fact sheet” to be added to my files. Such searches begin with the plant’s botanical name, which is almost always listed on the plant’s tag or nursery container.

As a result, I had a binder of such information for the plants in the Australian bed. Despite this preparation, I could not identify this plant.

After staring at my files for Australian plants, I realized that one fact sheet described this particular plant quite well, but the accompanying photo showed red flowers. The plant in question has white flowers!

Apparently, I had included a photo of a different cultivar of the plant. I learned that the red-flowered cultivar is more widely used than the white-flowered species in my garden. (The ‘Snow White’ cultivar has double, green-centered blooms, but my plant has single white blooms with unremarkable centers.)

I replaced the photo, and was satisfied that the plant is a Tea Tree or Manuka (Leptospermum scoparium), a member of the Myrtle plant family (Myrtaceae) and a native of Australia and New Zealand. The generic name means slender seeds, and the specific name means broom-like.

Tea Tree or Manuka (Leptospermum scoparium)

I then learned that this plant has several desirable characteristics. It is drought-tolerant, fairly slow-growing, appealing to bees and not appealing to deer. It has fragrant, evergreen foliage and a profusion of small flowers that appear in the late spring and summer, and linger into the fall. Its leaves can be brewed into a fine tea and Manuka honey produced by bees from its flowers has medicinal properties.

On the downside, at maturity this plant can reach ten feet tall and wide, making it too large for my Australian bed.

I considered pruning this shrub to manage its size. My Internet research found advice that the Tea Tree could be pruned after flowering to maintain shape and encourage bushier, more floriferous growth. However, pruning should never cut into bare wood “as new growth is unlikely to sprout.”

This reflects the pruning advice for plants that also flower on the previous year’s growth, including Camellias, Rhododendrons, Lavenders, and several others. This is critical information, because hard pruning of the Tea Tree would leave it looking and performing essentially dead.

While a light pruning after pruning would stimulate next spring’s growth at the ends of branches, there is no opportunity to reduce and maintain this sprawling plant to a more compatible size. If had been grown as a hedge or as a backdrop for the garden, it could have had long-term value in the landscape. In its current stage of growth and its present location, however, it will be an increasing problem.

This assessment of a particular plant recalls a basic guideline for landscape planning: always know a plant’s size at maturity before buying and placing it in the garden.

Great satisfaction can result from a well-placed plant. Conversely, removing a healthy plant leads to regret. From a positive perspective, removing the Tea Tree will eliminate conflict with nearby plants and free space for smaller Australian native plants.

WInter Bloomers from Mexico

There’s a lot that I’m thankful for, including a couple fall-season bloomers in my garden.

I have recently mentioned these two plants, which are natives of Mexico, but they are blooming right now and deserving of attention.

The first is the Tree Dahlia, which produces attractive blossoms in November, and also astonishes me each year with its annual growth. The Tree Dahlia (D. Imperialis) originated in the mountains of Mexico and Guatemala. It is an historic favorite of Mexican gardeners, and an ancestor of the garden dahlia, Mexico’s national flower and a current focus of hybridizers.

Tree Dahlia in bloom

Botanists travelling with the Spanish conquistadores discovered the Tree Dahlia and brought it to the Royal Gardens of Madrid by the late 1700s. The genus became popular throughout Europe and was recorded in the United States bas early as 1821.

In one season, a Tree Dahlia with established roots will grow up to twenty feet tall, with clusters of lavender pink blossoms high in the air, to be enjoyed from below. The blossoms are free of fragrance, which is not a problem given their height.

If a Tree Dahlia were to be planted below a deck of just the right height, people could appreciate the blossoms more closely. That would be a fine deck-plant combination.

The magical nature of this plant is its annual cycle. Around March, after it finishes blooming and its leaves have faded, the canes can be cut to about six inches from the ground to stimulate new growth from the roots.

The canes can then be cut into sections and planted to start new plants. Each section should have at least four leaf nodes and still leaking liquid sap. These cuttings are then planted right side up in sandy soil or potting mix and watered from time to time, until they show new green shoots. This plant is not difficult to propagate!

I first encountered the Tree Dahlia several years at a Master Gardener workshop, when someone shared cane sections. I planted those sections at the edge of my garden, in a partially shaded area. They grew quickly.

This plant is available commercially at least occasionally from Annie’s Annuals and Perennials, and few other sources. It’s a good example of a “pass-along plant.”

Given an appropriate site, it is a spectacular seasonal addition to the landscape.

Blossoms of the Daisy Tree

A second favorite plant at this time of the year is another Mexican native, the Daisy Tree (Montanoa Grandiflora).  This is an upright, evergreen shrub that grows up to ten feet tall and wide. It develops large, deeply lobed, rather leathery tropical looking leaves.

In November, it produces clouds of daisy-like flowers, white with yellow centers, with the fragrance of chocolate or freshly baked cookies. After about a month, the blossoms are replaced with long lasting “bouquet-worthy” chartreuse seed heads.

In the early spring, the branches should be cut to the ground to stimulate a new cycle of growth. Like the Tree Dahlia, this plant grows vigorously from its roots to produce a striking new presentation each year.

My first introduction to the Daisy Tree was during a visit to the Esalen Institute on Big Sur, during a stop on a tour hosted by the Pacific Horticultural Society. I was impressed by the plant, and searched diligently for a small plant for my garden. It’s not offered widely, but I found it it eventually at Annie’s Annuals & Perennials.

This is a large shrub, so it works best in the landscape if it’s placed in a space large enough to accommodate its spread, and close enough to a walkway to enjoy its fragrance. While it is evergreen, the recommended practice for rejuvenation pruning means that the garden design should anticipate its periodic absence. When the gardener cuts down the Daisy Tree, he or she might plan to fill the void with wildflowers.

Plants like the Daisy Tree and the Tree Dahlia bring dynamic qualities to the landscape, and welcome gifts to the holiday season. 

Palm Trees of Santa Cruz

While browsing an online update from the San Francisco Botanical Garden, I discovered the Chilean Wine Palm (Jubaea chilensis), which is interesting to me because my garden includes a section for Chilean plants.

Santa Cruz also has at least two Chilean Wine Palms, which is another species with pinnate fronds. A prominent specimen can be seen on the hillside below Mission Santa Cruz, toward the downtown area, close to an Australian Bunya-Bunya tree (Araucaria bidwillii).

A Chilean Wine Palm in Santa Cruz

This tree is unusual because it develops an unusually thick trunk, grows very slowly, and produces sap that can be used to make wine. The tree becomes rather too tall at maturity (eighty feet, potentially) for my garden.

Still, learning about the Chilean Wine Palm enticed me into exploring the world of palm trees. This column provides only a brief introduction to these interesting trees, which are widely used in California’s landscapes.

Palm trees are members of the botanical family Arecaceae, with some 2,600 species. Several different plants are included in this family; only the tree-form plants are called palm trees.

Types of palm trees can be grouped by the form of their leaves, which are called fronds.

  • Palmate leaves are characteristic of fan palms. The leaf parts radiate outward from a central area.
  • Pinnate, which is the most leaf form, resembles a feather with a central rib, with the ends divided into individual leaflets.
  • Bipinnate fronds resemble a fish tail.
  • Entire fronds, which are the least common form, resemble pinnate leaves but are not divided at their ends into individual sections.

There are quite a few palm trees in Santa Cruz. If you deliberately look for them while driving about, you will notice many trees and several different varieties. Some of the more recognizable varieties growing locally are the following:

Mexican Fan Palms (Washintonia fillifera) along the Santa Cru Boardwalk

Queen Palm (Syagrus romanzoffiana). Several of these very popular trees have been planted fairly recently, particularly near the Wharf/Boardwalk area. They line the main street of Capitola Village. Pinnate fronds.

Mexican Fan Palm (Washingtonia robusta). This is the tree along Beach Street. In 1962, former Boardwalk president Laurence Canfield planted 42 trees on this street and donated them to the City of Santa Cruz. These trees can grow 100 feet tall and live for 100 to 150 years. Palmate fronds.

California Fan Palm (Washingtonia fillifera). These are the only palms native to the west. Compared with the Mexican Fan Palm they grow shorter (about sixty feel tall) and develop thicker trunks. A good specimen can be seen on Morrissey Boulevard, near Fairmount Street. Palmate fronds.

Canary Island Date Palm (Phoenix canariensis). These trees can grow to sixty feet tall, with canopies thirty feet across. A fine specimen is in the garden of the Santa Cruz City Hall, reportedly planted by birds many years ago. Also, a pair of these trees is at the Darling House, on West Cliff Drive.  Pinnate fronds.

For an extensive catalog of local palm trees, with photos and descriptions, visit Peter Shaw’s blog, Dr. Shaw is Horticulture Department Chair at Cabrillo College, and a self-confessed tree guy. His blog also includes information on a wide range of trees in addition to palm trees that can be found in Santa Cruz County.

The large family of palm trees include a great diversity of shapes and sizes, so one or more of these plants might bring a welcome look to your landscape. In any event, you can appreciate these icons of tropical environments in our community.