Historic Issues in the Garden

The growing community of organic gardeners—which hopefully includes you—represents the “good guys” in several current struggles between public and private interests in gardening and commercial agriculture. Gardeners and farmers are quite different in many respects, but both are engaged in growing plants.

Mother Nature also grows plants, and has been doing so successfully since the dawn of time.

For about 10,000 years, gardeners and farmers have cooperated with Mother Nature to grow and harvest plants to eat, treat illnesses, dye fabrics, and enjoy their beauty and fragrance. They gradually developed ways to increase yields, reduce the work of growing and improve the qualities of their plants. For the most part, these changes have been compatible with natural processes.

Eventually, people adopted various technologies to improve gardening and especially farming. Beginning 4,500 years ago, various inorganic materials and organic substances derived from natural sources were used as pesticides. Major agricultural technologies include the mechanical reaper (1831) by Cyrus McCormick, and the tractor (1868), both of which brought new efficiencies.

In the 1940s, agribusiness began using synthetic chemical pesticides and great quantities of synthetic nitrogen fertilizer. In both cases, there was little or no knowledge of the impacts of these chemicals on human health or the environment.

Rachel Carson’s book, Silent Spring (1962) raised awareness of the conflict between public and private interests related to agrichemicals.

In the 1970’s, research began to development Integrated Pest Management (IPM) strategies, which rely upon natural processes and do not use synthetic chemicals. IPM became widely used beginning in the late 1970s.

During more recent decades, continuing research and development produced more selective products, including glyphosate, which soon became most widely used herbicide, worldwide.

The ancient methods of organic gardening continued throughout this history, but the seeming cost-effectiveness of uses of agrichemicals dominated commercial agriculture.

Today, we are discovering the consequences of attempts to fool Mother Nature. Insects are developing resistance to synthetic insecticides, weeds are developing resistance to synthetic herbicides, and we are discovering that at least some of these materials threaten our health.

The State of California already has listed 800 chemicals known to cause cancer or birth defects or other reproductive harm, and early this month issued a notice of intent to classify glyphosate as a carcinogen.This classification is based on the findings of the World Health Organization. See: CSG Prop 65 Heirloom EXPO FLYER Glyphosate 9-7-15.

In addition, speakers at recent conferences have called for uses of regenerative agriculture, which is a form of organic farming designed to build soil health or regenerate unhealthy soils. This practice could counteract “conventional” agriculture’s destructive practices, which include uses of synthetic chemicals. Many of those chemicals weaken or kill the soil microbiota, and thereby disrupt the natural carbon cycle and contribute substantially to global warming.

By any measure, we are now in a historic period of change, to reject shortsighted agricultural technology and return to more natural processes. Our health and the health of the environment depend on the success of this transition.


Carbon Farming

Climate change has been described as the consequence of the Industrial Revolution, which introduced extensive burning of fossil fuels. This practice disrupts the natural balance of carbon in the soil, the atmosphere and the ocean. Plans to slow or reduce the process of climate often emphasize reducing uses of fossil fuels.

Recently, and all too briefly, we explored the relationship between gardening and climate change. We have learned that common agricultural practices generate about one-third of the surplus CO2 in the atmosphere, making commercial farming a substantial part of the climate change problem.

Prior to the development of modern agriculture, we had organic farming, which is generally compatible with natural processes. The practices we now call “conventional” farming include driving a tractor, tilling the soil, over-grazing, and using fossil fuel-based fertilizers, pesticides and herbicides.

Similarly, farm animals once were raised in pastures, where they grazed on grasses and other plants. Today, cows, pigs and chickens are raised in tight quarters, provided grains and other feed that they work hard to digest, and must be dosed with antibiotics to maintain basic health.

These contemporary, presumably efficient methods are depleting the carbon stores in the soil, and reducing the soil’s natural ability to support plant growth and store moisture.

Soil scientists and environmentalists have been discovering land management strategies that can reduce the rate of loss of soil carbon, and even improve the rate at which agriculture can convert atmospheric CO2 into plant material and soil organic matter. When thoughtfully applied, carbon methods can add significantly to the rate of soil carbon sequestration, and actually reverse the climate change process.

Dozens of specific practices are included in carbon farming; all look like historical organic farming and common sense. The principal methods are composting, grazing by hoofed animals (ungulates), maintaining high percentages of organic matter in the soil (to feed the microbiota), supporting biodiversity, rotating crops and discontinuing uses of synthetic chemicals. The most effective practices orchestrate multiple methods in plans designed for specific circumstances.

Carbon farming, also called regenerative agriculture, should be part of the global response to the threat of climate change, but reduced burning of fossil fuels will still be important.

These promising methods for the management of agricultural lands can have substantial impacts when applied on a large scale, but they also have value when applied in residential gardens. In this column, we have advocated organic methods as beneficial to our flora and fauna. We find now that these methods also have long-term benefits to the health of the soil and the natural balance of carbon in our environment.

For more about this important topic, read Kristin Ohlson’s book, The Soil Will Save Us (2014), (which a reader recommended to me), and search the web for “carbon farming” and “regenerative agriculture.”

If you are growing plants and raising animals on hundreds of acres, try carbon farming. If not, by all means, garden organically!

Interactive Gardening

Our interactions with other persons or things can be among our most absorbing, challenging, satisfying—and occasionally most frustrating—activities. Examples include raising a child, working with colleagues, living with a spouse, cooking, and, yes, gardening.

Early uses of the term, “interaction,” dating from 1832, emphasize reciprocal action, i.e., the action or influence of persons or things on each other.

In this digital age, “interaction” often refers to the responses of computer software to a human operator’s inputs, e.g., keyboard entries, voice commands, or other forms of messaging. True human–computer interactions include the human’s responses to the computer’s output.

In this column, we are focused on gardening.

Interactive gardening means a gardener’s actions on a plant, the plant’s responses to those actions, and the influence of the plant’s responses on the gardener’s future actions.

Some gardener’s believe they can influence plant growth by talking to, or playing music to, the plant, but plant scientists tell us that while plants are very sensitive to their environment, they are unaware of their gardeners or sounds.

For a scientist’s analysis of the ways in which plants experience the world, read What a Plant Knows: A Field Guide to the Senses, by Daniel Chamovitz (Scientific American, 2012). The author reviews the research into what plants see, smell, feel, hear and remember, and how they know where they are.

Chamovitz shows that plants are aware—in highly evolved and surprising ways—of “external pressures that increase or decrease a plant’s chances for survival and reproductive success.”

For this reason, interactive gardening involves the gardener managing the plant’s environment, the plant responding to the environmental conditions, and the gardener noting the plant’s response and modifying his or her actions to achieve an intended response by the plant.

The gardener can affect all aspects of the plant’s environment, including the amount of light, heat, wind and moisture; the structure of the soil; the availability of natural or synthetic nutrients; and the presence of pests and diseases. Planting a seed involves modifying its environment.

The gardener also can interact directly with a plant, but only by touching or cutting the plant by pruning, dividing or transplanting.

For example, the Sensitive Plant (Mimosa pudica) responds to even a light touch by causing its leaves to fold or droop. This unusual response could be a defense against herbivores or insects that might be startled by the plant’s sudden movement.

As an aside, landscaping and flower arranging do not qualify as interactive gardening because the landscaper or arranger seeks to encourage responses from other humans, not from the plants.

When we consider gardening as an interaction between the gardener and the plant, we realize that the gardener’s success grows with his or her understanding of the plant’s responses to environmental conditions.

This encompasses simple responses, e.g., drooping from lack of moisture, less obvious responses, e.g., slow growth from lack of soil nutrients, and more complex responses, e.g., failure to set fruit from lack of seasonal chill.

Mastering the responses of plants to numerous environmental variables, and differences between plants from various native habitats, can be a lifelong study. Still, every gardener doesn’t need to study all plant’s cultivation preferences, or complete advanced studies of plant science. The gardener who wants to succeed and enjoy the experience should, however, learn about the needs of each plant in his or her garden.

More Interesting Than Dirt

Gardeners should refer correctly to the essence of our gardens, which is soil, and avoid calling it “dirt.”

Most soils consist of three groups of particles: sand (the largest in size), (clay (the smallest in size) and silt. The percentages of sand, clay and silt determine the texture of the soil. The best soil for gardening, called loam, has nearly equal parts of sand, silt and clay. Soil with this texture has good balance between retaining and draining moisture.

St another level, garden soil is a living environment, an ecological system, with microorganisms, decaying organic matter, earthworms and other insects. Each of these components contributes to the soil’s habitat for flora and fauna. Living soil involves a vast number of interdependent activities, which combine to create a complex and dynamic environment. These functions are enough to keep soil scientists studying for their lifetimes and motivate gardeners to at least appreciate what is going on under the surface of their gardens.

By comparison, dirt might contain a good mix of sand, silt and clay, but lacks any of the organic components of good garden soil. Dirt can be regarded as raw material for conversion to garden soil by adding organic matter (compost); this process will provide food for beneficial microorganisms and support the eventual development of the ecological system.

Dirt with a less than ideal mix of sand, silt and clay often can be improved by adding compost. Adding sand to a clayey soil, or clay to a sandy soil, might seem like a good idea, but it very difficult to create a good mix and usually results in something like concrete. Just add compost.

When we think of things that we cannot live without, many people will list sunlight, air and water, but not include soil, which is the essential fourth contributor to life on earth.

With this in mind, soil scientists from around the world have joined to name 2015 as the International Year of Soils, with the goals to educate the public about the importance of healthy soils. The Global Soils Partnership, which includes the United Nations’ Food and Agriculture Organization <http://www.fao.org/soils-2015/en/>, The Soil Science Society of America <www.soils.org/iys>, and many other groups, is spearheading these efforts. We are pleased to support this educational initiative.

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The Partnership has identified a theme for the educational activities of each month during 2015. The theme for April is “Soils Clean and Capture Water,” which is timely during California’s current severe drought conditions. As a group, the monthly themes provide an overview of the many ways in which soils support the quality of life on Plant Earth.

  • January – Soils Sustain Life
  • July – Soils are Living
  • February – Soils Support Urban Life
  • August – Soils Support Health
  • March – Soils Support Agriculture
  • September – Soils Protect the Natural Environment
  • April – Soils Clean and Capture Water
  • October – Soils and the Products We Use
  • May – Soils Support Buildings/Infrastructure
  • November – Soils and Climate
  • June – Soils Support Recreation
  • December – Soils, Culture, and People

Each gardener can support the International Year of Soils, in these ways:

All plants respond to good soil!

Flat Fruit Trees

One of the oldest advanced techniques of gardening—and one of my favorites—is espaliering, which involves shaping woody plants into two-dimensional shapes. Now, in bare root season, it’s timely to consider this tree training technique.

Espaliering has been traced back to the walled gardens of Persia, as long ago as 4,000 B.C. It was practiced during the Roman Empire and developed further during the Middle Ages.

There are good reasons for training trees or shrubs into relatively flat shapes. The primary reason in many situations is to garden productively within a limited space. Adding one fruit tree might be possible in a smaller garden, but even trees growing on dwarf rootstock can require a ten by ten area, plus some walking-around space, for cultivation. A gardener could use this tree training technique to grow several different trees in the same 1oo square feet.

Espaliers - Les Quatre Vents

These espaliered apple trees were growing at Les Quatre Vents, a notable private garden near Quebec, Canada. I took this photo in August, 2013

Espaliering is especially useful in narrow spaces along a driveway or sidewalk, or between the house and the property boundary. With an appropriate training plan, the gardener can maintain a row of fruit trees at a height of three or four feet, in a low profile that is both accessible and attractive.

Espaliered Apple Tree

Reader Bob Lippe of Seaside photographed this apple tree near a chateau in the Loire Valley, in France. The tree was being maintained at a height of only two feet.

If you have a space for which you might like to grow an espalier, check first to determine whether sun exposure is sufficient for the plant(s) you would like to install in the space. The most popular plants for espaliers are fruit trees, particularly apples, apricots, cherries and pears. In addition to fruit trees, other plants also can be grown in flat panels, including berries and climbing plants.

All the popular fruit trees—and most fruiting or flowering bushes or vines—require six or more hours of direct sunlight each day. Specific fruit tree varieties will perform better than others in the Monterey Bay area, so it would be prudent to do a bit of research before buying a tree for this purpose, or any other garden use.

Local garden centers usually offer only varieties that are appropriate for the immediate area. One could also seek the advice o the local chapter of the California Rare Fruit Growers < http://www.crfg.org/>.

In addition to making good use of limited space, espaliering has at least two additional benefits. One is to increase a fruit tree’s productivity. Training a tree to a two-dimensional form emphasizes horizontal branching, which maximizes the development of fruiting spurs. In addition, the flat form exposes more of the branches to sunlight and air, which promotes fruiting.

The second additional benefit is the opportunity for creative expression. Over the years, gardeners have developed many patterns for shaping the branches of trees and shrubs: fans, candelabras, and multi-tiered shapes are simplest to manage and most popular.

A special form of espalier, the cordon, is a single-trunked tree that develops spur clusters along its length. In this approach, branching is avoided and the trunk is trained to forty=-five degrees to the horizontal. A variation, the step-over design, brings the trunk to the horizontal, forming a low border.

For advice on growing fruit trees, attend a fruit tree workshop, such as those offered by the Friends of the UC Santa Cruz Farm & Garden: call (831) 459-3240, email casfs@ucsc.edu, or visit the Brown Paper Tickets website at http://tinyurl.com/workshops2015.

For specific information on espaliering, visit a bookstore, public library or Amazon.com for Allen Gilbert’s “Espalier: Beautiful Productive Garden Walls and Fences” (Hyland House, 2009). Any of several other more general books on pruning also would be helpful.

Visit your local garden center now for an early selection of bare root fruit trees.

Watering Roses in Summer

Q. Dear Mr. Karwin: I can’t find any guidance in my various gardening books on how much water one should give roses after they have stopped blooming (most of mine have), especially between now the beginning of the rainy season. Any suggestions? Many thanks.

August 2013

A. Roses should be watered even after blooming to keep them healthy and growing. This is important during hot summer weather, when the plants could be heat-stressed. Be sure to let them dry out between watering sessions, particularly for roses in containers.

Here is independent advice (unfortunately I lost track of the source):

Summer Watering Tips

Roses like infrequent, deep watering as opposed to watering a little bit every day. They prefer a good deep soak and then like to be dried out before receiving another deep watering.

How do you know if your roses need water in the first place? The leaves may droop and lack the suppleness they normally have.  (Don’t confuse this with the drooping that often occurs when temperatures exceed 90 degrees).

How will you know if you’ve watered too much? The foliage may feel spongy and may turn yellow. If watering from overhead, do so early enough in the day so the foliage has time to dry out before nightfall.  Spraying the leaves with water will often wash away any disease causing spores before they have an opportunity to take hold. So don’t hesitate to do this on a hot, dry day. Your roses will thank you for it!

Best wishes,

Rose Leaves in Winter

Q. I have a question for you about my roses. I live in Pacific Grove, my roses have leaves on them. Should I strip them off or cut below the leaf growth? One of my family members says leave them alone.

December 2013

A. At this time of the year, it’s appropriate to strip leaves from roses to encourage dormancy. Just pull them off by hand and rake up under the rose bush to minimize any disease and over-wintering pests.

Gardening with Succulents

The continuing popularity of succulent plants is based on several kinds of appeal, beginning with drought tolerance and including interesting shapes and an amazing range of colors.

This diversity occurs because plants in many genera have developed the capacity to store water in their roots, stems or leaves. Their common characteristic is that they live in areas where drought conditions happen often enough to make water storage essential to survival.

Succulent plants have a reputation for being easy to cultivate, relative to other perennial plants. In addition to needing water only occasionally and in small amounts, these plants are have few problems from pests and diseases.

The native environment of a succulent plant can be important to its cultivation. Most gardeners know that succulents need fast-draining soil to avoid root rot, and grow well, if slowly, in nutrient-poor soil. These plants have evolved under such conditions, and now depend upon them.

Another consideration is the elevation of the plant’s native environment. Succulent plants that have evolved on mountains are accustomed to those environmental conditions, and could have unique leaf anatomy and photosynthetic characteristics.

Good gardening practice often involves matching—or approximating—the plant’s native environment, but changing the elevation of one’s garden is not among the options. Happily, most succulent plants from high elevations can grow well at lower elevations.

Succulent plants grow in many areas of the world, and an important issue of native environment is the hemisphere in which the plant evolved. This determines the plant’s dormancy, which influences the gardener’s cultivation practices.

Succulent plants that have adapted to the northern hemisphere  are Winter Dormant:
they rest from November through February and grow from March through October.
Many plants also will rest for a few weeks of hot weather in the summer, and grow
again in September and October. Popular succulent genera that are Winter Dormant include Agave, Echeveria, Euphorbia, Lithops and Pachypodium.

Succulent plants that have adapted to the southern hemisphere are Summer Dormant, which also means that they are winter growers. Their rest period continues from May through August; they grow slowly during the winter months, and then grow actively during autumn and spring. Examples of Summer Dormant succulent plants include these popular genera: Aeonium, Aloe, Cotyledon, Crassula, Dudleya, Gasteria, Graptopetalum, Haworthia, Kalanchoe, Pelargonium, Sanseveria, Sedum and Senecio.

The gardener should avoid disturbing succulent plants during their dormant periods. So, repotting, pruning, or taking cuttings should be done in March for Winter Dormant plants and in August for Summer Dormant plants.

Watering succulent plants is another practice that is dormancy-related. When plants are dormant, they stop growing but continue to transpire, and therefore need replacement moisture. Not watering succulent plants while they dormant is the most common cause for failure.

The amount of moisture needed during dormancy depends on the dryness of the particular environment. Winter Dormant plants might need watering once or twice per week. Summer Dormian plants, which rest during the hottest time of the year, could need more frequent watering.

Also, remember to group plants with similar water needs. Such grouping can be important when combining succulent plants in containers: keeping Summer Dormant or Winter Dormant plants together will enable more convenient and more appropriate irrigation.

Mixed Succulents in Pot

Mixed Succulents in Container
(click to enlarge)

These guidelines could need adjustment for individual species; as always with the plant world, general rules are subject to variation.

Top Ten Tasks for Fall

Our gardens have had some rain—and a promise for more this season—so we can now pursue “regular” gardening and think other good thoughts!

There are no exciting new developments or flights of imagination in this week’s column. Instead, here’s a review of steps to take in the fall to ensure gardening success in the spring.

  1. Feed your soil. As plants grow, they consume the soil’s nutrients, so the gardener should restore the soil by adding partially decomposed organic material. For an inactive bed, dig in a three-to-four inch layer of compost; for an active bed, provide the same layer as a top dressing.
  2. Mulch your beds. Cover any bare soil in the garden with organic or inorganic mulch to conserve moisture and discourage weed growth. For large areas, call your local tree service for a load of coarse wood chips, which break down slowly and are typically free.
  3. Plant spring flowering bulbs. There’s still time to create a delightful display. Online sources and garden centers are running low, but look for bargains. Even second-choice bulbs produce fine spring flowers.
  4. Wait to do clean up until spring. Leave faded perennials and grasses in place for now to decorate the garden and provide habitats for beneficial insects. Cut them back when you see signs of new growth in the spring.
  5. Plant perennials. Continue adding plants to the garden any time before frost. To avoid compacting the soil, let any rain soak in well before working or walking on the soil .
  6. Sow wildflower seeds. If you have enough garden space for even a patch of wildflowers, sow a small packet of mixed wildflower seeds. If you have a larger space, sow more seeds! This project is easy, inexpensive and very satisfying for the gardener, and great for the wildlife.
  7. Make notes on planting for fall color next spring. A little planning during the quiet days of the fall could support next spring’s installation of plants that will provide fall color and seed heads for the birds. A beautiful garden in the late summer and early fall requires a bit of study to identify and locate plants that will fit well into the landscape and put on a pleasing show.
  8. Control slugs and snails. The fall presents time for defensive action against the brown snail (Cantareus asperses), a significant pest in many gardens. Snails can reproduce on a year-round schedule, so the fall is a good opportunity for control only because other tasks are less pressing, and we want to give the new spring growth a chance to flourish. A reliable approach is picking snails by hand and dropping them into water with a tablespoon of rubbing alcohol. Other methods: lure them into shallow pools of cheap beer, or send your pet duck after them.
  9. Compost your tree leaves. Leaves that fall from your trees are not trash, but “gardener’s gold,” an excellent and free source of pre-compost. You might feel the need to rake your leaves into a pile (not everyone does), so the next steps will define your gardening priorities. One option is to wrestle them into trash bags, which is not a simple step on the way to the landfill. The preferred option is to shred the leaves to speed decomposition and add them to your compost pile. To shred the leaves, use a bagging lawn mower or a purchased or rented leaf shredder.
  10. Collect seeds. Watch for seed heads to form on your favored plants, cut the flowering stems at the base, drop them into a paper grocery sack that you have carefully saved, and let them dry for a week. They are then ready to sow in the garden, with or without the stems. If desired, separate the seeds from the chaff for storage or sharing.

You might know additional tasks that would ready your garden for winter, but these ten steps would be good preparation for a glorious spring season. Gardening is about the future.

Gardening to Save the Planet

We are learning about humanity’s many impacts on the near and distant future of our planet. Some people are in denial about these impacts, while others are concerned and ready to do whatever we can to ensure that our Earth will support future generations.

To support and encourage such positive action, leading botanist Peter Raven will visit the UCSC Arboretum next week to meet with UCSC faculty and staff, and present a public talk, “Saving Plants, Saving Ourselves.” Raven will present an informed update on the increasing threats to Earth’s environment, and emphasize the special role of public gardens in conserving plants that could be lost through habitat loss and climate change.

Peter Raven has a long friendship with the UCSC Arboretum, and a national reputation as a conservationist and advocate of global biodiversity: Time magazine hailed him as a Hero of the Planet. His visit to the Monterey Bay area inspires us to reflect on the home gardener’s unique role in saving the planet.

Here are ten everyday practices that gardeners can apply to help sustain the environment and protect plant diversity.

  • Irrigate your garden wisely, using drip technology to deliver water only where needed, and mulch (organic or inorganic) to minimize evaporation and weed growth.
  • Recycle household water into the garden, using plant-friendly soaps and detergents.
  • Prune your acquisitions of consumer goods that bury our landfills and clutter our environment…and that you really don’t need.
  • Propagate plants that Nature’s pollinators (bees and other insects, bats and birds) love and need to survive. Clusters of flowering plants will enrich your landscape.
  • Conserve biodiversity by protecting endangered species and including rare and threatened California native plants in your landscape. (Visit the California Native Plant Society’s website, www.rareplants.cnps.org/ for info.)
  • Nourish your plants with organic fertilizers, and discontinue uses of artificial chemicals
  • Control plant-eating insects with insect predators and organic insecticides. Use physical barriers and non-toxic deterrents to control other plant-eaters, e.g., snails, gophers and deer,
  • Select plants that are native to California or other summer-dry climates, to enable their healthy growth, support wildlife and ease your gardening workload.
  • Compost the “carbon-rich” fantasies of climate change deniers with the “nitrogen-rich” facts of the world’s scientists to promote wise stewardship of the environment. (Alto, keep all biomass on the property by composting green garden waste!)
  • Cultivate these good practices among your friends and neighbors.

The UCSC Arboretum employs these practices regularly, and assigns high priority to its work in plant conservation.

pt sur Austin and Tim

Click to Enlarge

This photo shows UCSC student Austin Robey and Arboretum volunteer Tim Forsell as they replanted endangered California native manzanita shrubs on a steep slope near the Point Sur State Historic Park and Lighthouse. The Arboretum’s Brett Hall coordinated the conservation project.

Your practices in your own garden also could help to save the planet. A good start would be to attend Peter Raven’s talk..


Registrations for the Peter Raven talk sold out quickly. To receive timely announcements of future events at the Arboretum, visit arboretum.ucsc.edu/get-involved/.

If you would like to sponsor an educational event at the UC Santa Cruz Arboretum, contact Jennifer Macotto, 831-427-2998 or jmacotto@ucsc.edu.

For information on how you could help save a rare species: visit arboretum.ucsc.edu/education/plant-sponsorship/.