Pruning Daphnes and Salvias

According to meteorologists, the Spring Equinox occurs tomorrow (Saturday), just before midnight, but the first full day of spring will be on the following day (Sunday).

In any event, spring’s arrival inspires many thoughts of gardening opportunities. This column addresses three timely tasks.

Propagating Plants from Cuttings

First, real gardening includes the propagation of plants. One method for getting new plants that is particularly good in the early spring is taking cuttings from existing plants. The timing is good because cutting from the new growth of existing plants can be rooted easily.

Practicing this technique is both frugal and fun, so survey your garden and the gardens of others for plants that you would like to propagate, either to add to your own garden or to gift to other gardeners. If you want more of someone else’s plants, ask permission to take cuttings!

Start by preparing your containers, e.g., small plastic nursery pots, by filling them with planting mix from a garden center, rather than garden soil, which might have bacteria or fungi that could harm young plants.

Using clean clippers, take cuttings of about three inches from the tender green growing tips of plants. The cuttings should be flexible, not woody.

Strip the lower leaves from the cuttings, and insert the stems into damp soil. Place the planted containers where they will be warm but protected from direct sunlight.

Follow up by keeping the cuttings moist. This involves occasional watering and perhaps providing a mini-greenhouse of plastic sheeting to reduce water loss from evaporation. If moisture condenses on this covering, the cuttings could be too moist and vulnerable to fungal problems, so remove the covering for an hour or two to let the excess moisture evaporate.

Your new plants could require several weeks to establish roots, at which time they will develop new leaves. To check their status, tug very gently on the cutting to detect resistance from the new roots.

When you have rooted cuttings, move the plants into larger containers or the garden, and congratulate yourself.

Propagating Plants from Seeds

Planting seeds is also a frugal and fun approach to real gardening. The process is very similar to propagation from cuttings, but it offers a broader range of options and requires more time.

Seeds are available from garden centers. If you want to grow varieties that are not offered by a local garden center, visit Cyndi’s Catalog of Garden Catalogs (www.gardenlist.com/) for many, many options.

Almost all seed packets have basic instructions for growing the particular seeds.

Propagating Plants from Plant Sales

You could get more of the plant you like by just buying them. That approach also works for plants that are new to your garden!

Mark April 9th on your calendar for the combined plant sales of the UC Santa Cruz Arboretum and the California Native Plant Society, Santa Cruz County Chapter. For information, visit the Arboretum’s website (arboretum.ucsc.edu/news-events/events/).

Mark April 23rd & 24th on your calendar for the Spring Show & Sale of the Monterey Bay Area Cactus & Succulent Society. For information, visit the Society’s website (mbsucculent.org).

Spring is here and time to enjoy your garden!

Seasonal Pruning

The vernal equinox is really more significant for meteorologists than it is for gardeners. Some plants respond to changes in day length, of course, but they don’t perform differently merely because days and nights are equal in duration.

Still, the vernal equinox (March 19, 2016) is a useful marker for the change from winter to spring.

As the world experiences climate change, scientists who study the seasons (phenologists) are generating more interesting reports about bud break, flower opening, insect emergence, animal migrations and other seasonal phenomena.

We are already witnessing changes in our gardens: for example, my lilacs are blooming earlier than they have in previous years. Lilacs (Syringa vulgaris) typically require a significant chill during the winter months, but decades ago, Walter Lammerts, working at a southern California nursery now known as Descano Gardens, developed three low-chill lilac hybrids: ‘Lavender Lady’, ‘California Rose’ and ‘Angel White’ (pictured). Gardeners in the Monterey Bay area and similar climates can grow Descanso hybrid lilacs and enjoy their fragrance.

Lilac 'Angel White'

Lilac ‘Angel White’

At the same time, my salvias are fading noticeably, earlier than I usually see.

These two garden favorites have markedly different pruning requirements. The lilacs bloom on new wood, so they should be pruned soon after the blossoms fade, before new buds form. This work should be done before June.

Another important maintenance issue for lilacs manages their strong desire to spread through underground runners. When allowed to roam for a few years, a healthy lilac will form a thicket. This may be desirable, depending on the shrub’s location within the garden, but containment might be appropriate. Accomplish this by the straightforward approach of excavating and cutting off the runner that has created the unwanted new growth.

By contrast, salvias can be cut back to about six inches above the ground in early spring, as new growth appears at the plant’s base. Such renewal pruning cleans away the old growth and stimulates vigorous new growth on these garden standbys. The right time for this work will occur in about one month. It is OK to prune earlier before the new growth is evident, but the ideal timing will shorten the least decorative period for your salvias.

A friend, busy with other priorities, saw the traditional season for rose pruning come and go this year, and now asks if she should prune her roses late, or let them go until next year.

The general rule for roses is to prune during the winter months, when the plants are dormant. Still, the popular repeat-blooming hybrid tea roses should be cut back as blossoms fade during the summer months. According to David Austin Roses, this approach will stimulate blossoming and support maintenance of a desirable rounded shape for the plant.

If a missed winter pruning has allowed a rose to compromise its overall shape, the gardener’s strategy should include summer pruning, cutting back stems after blooms fade with shaping the plant in mind, as well as encouraging new growth.

Pruning can be a challenging task for the gardener because of differences in best practices for individual genera. A good pruning book can help to reduce uncertainty, put the gardener in control and make the process easier and ultimately creative.

Enjoy your garden and keep your pruning shears clean and sharp.

Send pruning questions to Tom Karwin

 

A Not-to-Miss Event

As we enjoy the final days of winter, warmly, we begin thoughts of the arrival of spring and the reemergence of our gardens. With exquisite timing, the annual San Francisco Flower & Garden Show brings the season into focus and offers an unparalleled array of inspiration, information and products to help avid gardeners to launch the year’s gardening activities.

The SF Show began over thirty years ago as a fundraiser for the San Francisco Friends of Recreation and Parks, and soon evolved into a commercial event that features landscape designers, speakers on numerous topics in gardening, and exhibitors of plants and a wide range of garden products.

The Show ranks as one of the nation’s three largest annual events devoted to gardening and landscaping. The others are the Northwest Flower & Garden Show, which was held in mid-February in Seattle, and the Philadelphia Flower Show, which will be held March 5–13. Since 1829, the Philadelphia Horticultural Society has sponsored the Philadelphia Show as a fundraiser.

The world’s most significant competitor to these three garden shows is the Royal Horticultural Society’s Chelsea Flower Show, to be held May 24–28, 2016, at the Royal Botanical Gardens, Kew (near London).

This brief survey of major garden shows indicates that the SF Show amounts to a major event for gardeners of the west coast, and a great and accessible resource for gardeners of the Monterey Bay area.

This year’s SF Show will include 125 free seminars by gardening experts who have been selected as effective speakers. The seminar speakers and schedule is available on the SF Show’s website. The seminars are scheduled in five different stages within the San Mateo Event Center, so your attendance requires a little planning.

The Show also includes over 200 exhibitors in the Plant Market and The Marketplace. If you need any new plants or tools or garden art, you are likely to find them at the SF Show. One of the favorite exhibits is the large display by Succulent Gardens, from near Moss Landing. Early word is that this booth will be larger than ever, in response to enthusiastic collectors of succulent plants.

I will bring a couple mail order catalogs of garden plants and supplies for reference in evaluating prices at the SF Show. The prices are reasonable, I believe, but I always appreciate bargains.

The highlight for many visitors will be the Showcase Gardens, which will include nine full-size garden displays of the talents of landscape designers and craftsmen from northern California. The gardens often dazzle visitors by providing elaborate presentations of beautiful plants, stunning settings and unique concepts. These gardens present thematic designs that incorporate many ideas that can be adapted for your own garden. The designers of course will welcome new clients, and most will also be on hand to answers visitors’ question.

A day at the SF Show is really close by, not expensive, and an exceptional opportunity to bring gardening ideas and riches back home. It should be on your calendar.

If You Go

What: San Francisco Flower & Garden Show

When: March 16–20, 2016

Where: San Mateo Event Center

Info: http://sfgardenshow.com/

Biochar: Ancient Soil Amendment

As we continue to learn about gardening, we are often reminded of nature’s essential role in the process, and, by extension, the wisdom demonstrated by historical gardeners as they worked in concert with nature.

We have countless examples of the benefits of “gardening with nature,” and ample evidence of the short-sightedness of technology-based agribusiness.

”Technology” as used here encompasses monocropping, animal feedlots and synthetic fertilizers and pesticides, as well as more constructive activities such as the use of drone aircraft to monitor crops.

One fascinating historical instance of natural gardening is biochar. The briefest definition of biochar is organic matter that has been heated to high temperatures with limited oxygen to produce charcoal. This process (pyrolysis) also produces gasses that can be burned to produce electricity.

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Biochar is very similar to charcoal, which is made principally from wood, and used in backyard barbecues and a variety of industrial processes. Biochar, by contrast, is made from all kinds of organic waste, particularly garden or agricultural waste, and is used as a soil amendment, adding carbon to the soil.

 

Note: The biochar photo is from a good article by Jeff Cox in Rodale’s Organic Life.

Biochar apparently has been produced and used for thousands of years by early gardeners in Brazil’s Amazon River Basin to improve their rather poor soils. In 1870, an American geologist and explorer discovered and reported areas of dark and highly fertile soil. Researchers puzzled over the origin of this unusual soil, called “terra preta” but recognized that it has strong benefits for agriculture.

During the past twenty years or so, scientists have attributed several valuable properties to biochar, beyond improving crop yields. The additional benefits include increasing water-holding capacity of soil, reducing the need for chemical fertilizers, reducing natural emissions of greenhouse gasses (nitrous oxide and methane) from agricultural soils, increasing soil microbial life, resulting in carbon sequestration, avoiding the natural decomposition of agricultural and forestry waste and thereby decreasing carbon dioxide emissions.

These benefits are stimulating great enthusiasm for uses of biochar in both gardening and agriculture. For example, scientist James Lovelock, author of The Gaia Theory, has written, “There is an outside chance that one procedure could really turn back the clock on Global warming and that is burying carbon. All you have to do is get every farmer everywhere to make a profit by turning all his agricultural waste into char and burying it.”

This success story has only an outside chance because it assumes universal participation by the world’s farmers, but does reflect the genuine value of biochar.

Still, individual gardeners could help to reverse global warming by using biochar. This material is available commercially, but it’s costly. A quick survey of sources on the Internet shows a typical price around $30 per cubic foot, enough to amend a garden bed of twenty-four square feet.

A gardener could produce biochar with little or no expense. Here are brief directions from Barbara Pleasant, Mother Earth News (2009): “Pile up woody debris in a shallow pit in a garden bed; burn the brush until the smoke thins; damp down the fire with a one-inch soil covering; let the brush smolder until it is charred; put the fire out.”

For more on this topic, visit the International Biochar Initiative.

Biochar could increase dramatically the fertility of your soil, and help you to rival the successes of ancient gardeners of the Amazon Basin.

More

A reader’s query and my reply.

Q: I read your article in Friday’s Sentinel about biochar. I am wondering if I can put used, regular, charcoal from the grill in the garden. There is always some left over. Can I break it up and put it in my garden?

It seems like I read somewhere years ago I could, but I can’t remember.

A: By “used charcoal” do you mean ashes?

I have attached a short article that is about Colorado’s soil, but California soil also tends to be alkaline, so the article has relevance in our area as well.

Charcoal is Not a Good Soil Amendment in Colorado

The bottom line is that charcoal ash, which is alkaline, would have some value when added to very acidic soil, i.e., low pH, but doesn’t add any fertility to the soil.

On the other hand, unburned, or partially burned charcoal briquettes (made from wood) could be useful as a soil amendment, although they have less nutrient value than biochar, which is made from a range of vegetative materials.

Charcoal briquettes usually contain cornstarch as a binder, and might include coal, lime and other ingredients, none of which would be harmful in the garden. Soften them in water to break them down, then dry the result to mix into fertilizers or directly into the soil.

I hope this is helpful

Another reader’s comment: 

Dylan Gillis

Fine article, though it sort of glosses over the fact that biochar itself is 99% carbon that stays in the soil for hundreds if not thousands of years. While compost only costs $3 or more per cubic foot (depending on quality, volume you buy and packaging/marketing variables) it needs to be replaced every year, forever, to result in similar levels of carbon sequestration and fertility. Of course the best is to add biochar, once to satisfactory levels, and then amend with compost for the nutrients and energy feeding the soil life, every year. In this approach you would use less compost to get the same or better results and your carbon sequestration would be more or less permanent!

Drama for the Landscape

 

One of the most spectacular plants from South Africa, in exuberant bloom at this time of the year, is Aloe arborescens. It can be seen throughout the Monterey Bay area, occasionally having spread into impressively large clusters of plants.

The specific name means “tree-like,” because the plant can grow to close to ten feet high. Structurally, the plant consists of several branches, each of which ends in a rosette of leaves edged with small spikes. Each rosette can generate several flower stalks that produce cylindrical inflorescences (racemes). The individual flowers, typically a bright orange-red, are tubular and attractive to hummingbirds. The clusters of flowers resemble the flame of a torch, leading to the plant’s common name: Torch Aloe.

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Several years ago, I planted my first specimen of this succulent plant, a single rosette, in a well-drained bed. It grew rapidly and extended runners (stolons) that produced new plants, ready to take over the bed. Not knowing its full growth potential, but realizing that it was too productive for that small bed, I shovel-pruned it, replanted three rosettes in front of a nearby compost bin, and placed most of the rest in the bin.

The replanted rosettes grew readily into a dramatic presence in my garden, and also shielded the compost bin from view.

A. arborescens is related to A. vera, a smaller, more familiar South African native that is popular for its ornamental, cosmetic and medicinal values: its juices reportedly have rejuvenating, healing, or soothing properties.

The Torch Aloe also reportedly has value in promoting good health. Some people advocate a drink made from the pureed whole raw A. arborescens leaf, unheated raw honey and 1% certified organic alcohol. This drink is claimed to support immunity from a range of diseases and provide general cleansing for the whole body. It is reported to be “bitter, but unctuous and savoury as well, thanks to the honey.”

I have plenty of leaves but have not tried the drink. This is not a testimonial.

A. arborescens is one of about 500 species of the genus Aloe, which includes natives of South Africa, tropical Africa, Madagascar, Jordan, the Arabian Peninsula and some islands in the Indian Ocean. Many grow well in the summer-dry climate of the Monterey Bay area. Most species, unlike A. arborescens, are stemless: the rosettes grow directly on the ground.

A smaller, yellow-flowered variant, called Golden Torch Aloe (A. arborescens lutea), can be found in limited numbers.

Another yellow-flowered form, Yellow Aloe, was discovered in a private garden in Santa Barbara. This plant might be a variant of A. arborescens, a hybrid with another species, or an entirely different species: A. mutabilis, which has red flower buds that mature into yellow.

Aloe arborescens can be an attractive and interesting addition to a landscape that has sufficient space.

Pollinator Friendly Gardening

The current period of warm weather surely doesn’t signal the end of El Niño rains, but it does bring to mind the coming of spring. And with that cyclical change comes the inspiration to plan for garden development.

Our gardens can support many different objectives. One timely objective to consider is to support healthy lives for nature’s pollinators, primarily bees and butterflies.

We have frequently touched upon the vital role that bees and butterflies fill in the propagation of plants. The development of fruits and vegetables, which are essentially seed cases, often depends on bees, and butterflies are important pollinators of wild and cultivated flowers.

Our pollinators are threatened by civilization, notably habitat loss and agricultural chemicals. In May of 2015, the U.S. Dept. of Agriculture and the Environmental Protection Agency, in response to a directive by President Obama, established the Pollinator Health Task Force. That multi-agency group has begun reporting on studies and releasing recommendations to help bees and butterflies. We can expect a continuing flow of constructive new directions.

In June of 2015, with endorsement by First Lady Michelle Obama, environmentalists created the National Pollinator Garden Network and launched the Million Pollinator Challenge, with the goal to create one million new pollinator gardens by the end of 2016. Clearly, individual gardeners are invited to join in nationwide efforts to support pollinators.

In this context, we have a new book by Master Gardener Rhonda Fleming Hayes: Pollinator Friendly Gardening, (Voyageur Press, 2015).

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This is a valuable resource for developing a garden that supports healthy lives for bees and butterflies. Fleming, a dedicated advocate of pollinators, provides a readable and complete introduction to the subject and maintains a calm and informative style. (We respect fervent commitment to a cause, but the strident alarms and urgent calls to action we sometimes see can be trying.)

Fleming offers three principals for pollinator-friendly gardening: provide blooming plants all year, allow nesting and overwintering sites, and avoid uses of pesticides.

She also focuses on native plants, which have co-evolved with many insects and developed reciprocal dependencies. These relationships are site-specific so that the plants and insects that are native to California are not the same as the plants and insects of the east coast of the U.S. Many garden books, including this one, address national readerships, so each reader should adapt plant lists to his or her own garden environment.

Also, note that honeybees were imported to the U.S. long ago from Europe and other regions, and do not relate to U.S. native plants in the same way as the thousands of species of U.S. native bees. Imported bees particularly appreciate plants from their native lands that have been introduced in the U.S.

Here are sources for more information on pollinator-friendly gardening:

The Pollinator Partnership

National Pollinator Garden Network

Xerces Society

Monarch Watch

Ladybird Johnson Wildflower Center

A pollinator-friendly garden has direct benefits for the bees and butterflies, and also serves the gardener with the pleasure of beautiful surroundings and the satisfaction of ecologically sound practices. Also, an enjoyable and educational counterpart to bird-watching is the emerging activity of bee-watching. There is much to learn from the bees!

Color in the Winter Garden

A good practice is to walk through your garden occasionally to see what is succeeding, and what might need changing. It’s rewarding to visit your plants in the spring, but the winter months (now) are when we look for dormant season instances of attractive color, form or fragrance.

In the Monterey Bay area, the dormant season brings nothing like the severe conditions experienced in some other parts of the United States, but our gardens still rest at this time, and might present only limited interest.

It doesn’t have to be that way! There are many plants that can enhance our gardens while other sleep, when we plan for all season interest.

A first step is to take note of plants that are already in your garden, and looking good right now. They might be providing attractive blooms or interesting foliage, taking the center of attention while others have dropped their leaves or died to the ground.

You could supplement the tour of your own garden with a walk through your neighborhood to see what looks good in nearby gardens. That approach automatically identifies plants that would thrive in the climate and soil conditions of your garden. It can also be a good excuse to meet new people, to ask them about their gardens.

My garden, while not a true all-season display, still has several plants that are attractive during the winter months. For example, succulent plants, which have done well during our drought period, can maintain their appearance during dormancy.

I recently renovated a small bed of Mexican succulents, and the plants are looking good. They will produce blossoms later in the year, but the forms and colors or their foliage works well year-round. The recent addition of a large Talavera bowl, recently added, serves to mark the bed’s Mexican theme.

Talavera pottery, offered by many garden stores, is a style of glazed ceramic pottery that dates to the Italian Renaissance. Authentic Talavera items are from the Mexican city of Puebla and nearby communities, but imitations (which includes my own piece) are widely available. Imitations from other parts of Mexico are properly identified as Maiolica, which refers to the decorative style.

Other plants that are starring during the winter include a Purple Lilac Vine (Hardenbergia violacea), an Australian native, now covered with small violet flowers; an enormous Candelabra Plant (Aloe Arborescens) from South Africa, blooming later than others in the area, and a favorite, a Variegated Winter Daphne (Daphne odora ‘Aureomarginata’), which offers both colorful evergreen foliage and a sweet fragrance that highlights the season.

Daphne odora 'Aureomarginata'

Daphne odora ‘Aureomarginata’

When provided good drainage and afternoon shade, daphnes are reliable performers for years until they suddenly and without apparent cause, give up. An older specimen recently showed arrested development: flower and leaf buds simply didn’t mature for months. After quizzing three knowledgeable friends, without success, I removed the plant (making space for another fuchsia). By this time, I already had three replacement daphnes growing nearby, so I still could enjoy the wafts of fragrance this year.

Prepare now to bring new interest to your garden for next winter with more seasonal bloomers and evergreen foliage, either adding specimens of existing plants that you like or bringing in good performers that you have seen in nearby gardens. Winter gardens can be very pleasing environments.

More

A quick Internet search or a visit to your local library or bookstore could lead to useful lists of winter-blooming plants. For example, one good source of information is Dan Hinkley’s book,  Winter Ornamentals.

Waiting for Organic Pot

A young friend recently took a look at my garden and suggested that I could grow a few marijuana plants for personal use.

I looked into it, out of curiosity.

Long before I searched for sources of seeds or seedlings, or cultivation advice, I learned that, unless I had a genuine medical need for the herb, growing marijuana (Cannabis sativa) in my garden would be illegal. The related regulations at the local, state and federal levels are full of contradictions and different perspectives, and are in flux.

I’ll wait.

Many hundreds of illegal marijuana “grows” exist already in the Monterey Bay area, and thousands in California, including many in California’s “Emerald Triangle” of Mendocino, Humboldt and Trinity Counties. The numbers are growing, and it is not difficult to find pot, if one were to be inclined to try it.

Last week, at the 36th annual Eco-Farm Conference, in Pacific Grove, Dr. Andy Gordus of California’s Department of Fish and Wildlife, described and illustrated the impacts of illegal and therefore unregulated marijuana grows in California. The growers are illegally clearing forest lands, damming streams, digging wells that drain streams that wildlife depend on, polluting waterways and killing wildlife with pesticides, leaving mountains of trash, and otherwise being really bad neighbors.

Marijuana plants, like other plants, are subject to a variety of pests and diseases, and growers use a variety of synthetic agricultural chemicals, including some highly toxic materials that are being smuggled in from Mexico. Such chemicals may be sprayed on growing plants, or applied systemically. Also, because rats and other animals chew through plastic irrigation lines, rat poisons are often used.

Marijuana products may be used by inhaling, ingesting, and absorbing through the skin. These diverse forms of use mean that users should ensure that their marijuana does not contain toxic substances. Consumers of marijuana products ideally could rely on the organic label, but at this time there is no such label for these products. Consumers can only rely on trusted sources.

California does not approve any aspect of marijuana cultivation, including pesticides, because it continues to be illegal at the federal level. The federal government also does not recommend pesticides for illegal crops.

In this bizarre environment, California has provided informational guidelines that include a short list of organic pesticides and natural rodenticides that “may be used in and around marijuana cultivation sites consistent with the label.” Visit www.waterboards.ca.gov and search for “Legal Pest Management Practices for Marijuana Growers in California.”

For more information, visit the websites of the Santa Cruz County’s Cannabis Cultivation Choices Committee, or Organic Cannabis Growers Society.

For now, I’ll wait.

During four days last week, the Eco-Farm Conference provided updates about a wide range of organic gardening and farming practices, and related state and federal policies. The short story is that organic, sustainable and regenerative gardening is healthy and expanding steadily. I’ll have more to report in future columns.

Labels are Important

Our gardens are mostly dormant during the winter, but government regulators never rest! This column offers a brief update on three current debates over garden-related regulations.

Labeling Foods as Genetically Engineered

Almost all consumers, when responding to surveys, have said they want labels on foods that are based on genetically engineered plants or animals. I wrote about this issue in late spring of 2015: go to ongardening.com to read “GMO Controversy.”

Consumers in several states, including California, have tried to require labels on such foods, but industry groups have argued against the related ballot measures. Vermont succeeded in adopting this labeling requirement, to be effective in July of 2016. Since then, opponents lost their legal challenge of the requirement, and failed to persuade Congress to ban such requirements (the House approved, the Senate didn’t).

Most recently, the federal Food and Drug Administration (FDA), responding to pressure4s from both side of the debate, issued “Guidance to Industry: Voluntary Labeling Indicating Whether Foods Have or Have Not been Derived from Genetically Engineered Plants.” In brief, the nonbinding recommendations of this Guidance allow voluntary labeling that is truthful and not misleading (as required by the Food, Drug, and Cosmetic Act, 1938).

The FDA is currently accepting comments on its similar draft guidance for labeling genetically engineered Atlantic salmon.

An increasing number of food producers are voluntarily labeling such foods, but the ultimate resolution, a uniform federal requirement, would benefit all parties.

Labeling Foods as “Natural”

FDA, responding to another set of pressures, has requested comments regarding “Use of the Term ‘Natural’ in the Labeling of Human Food Products.” The issue becomes more complex than it would seem at first. Long-standing federal policy interprets “natural” food to mean that it contains nothing artificial or synthetic that would not normally be expected to be in the food.

The Grocery Manufacturers of America want to label as “natural” foods derived from genetically engineered plants or animals.

The Consumers Union wants to prohibit the use of “natural” on any food labels, indicating that the large majority of consumers believe “natural” means no use of artificial materials, chemicals, ingredients, colors, toxic pesticides or genetically engineered plants or animals.

Labeling Garden Chemicals as Toxic

The World Health Organization has found that glyphosate, the active ingredient in the widely used pesticide RoundUp, is a probable carcinogen to humans. In response, consumer groups have asked California’s Environmental Protection Agency to label RoundUp as a carcinogen. The agency received comments on this action until late October of 2015, and is now considering those comments.

Most recently, the agency is currently receiving comments on proposed changes to clarify existing requirements for “clear and reasonable” warnings of a variety of exposure situations.

Another chemical that is under fire is imidacloprid, one of the neonicotinoid insecticides (called “neonics”) that has been linked to risks to honey bees hives. The federal Environmental Protection Agency (EPA) had approved agricultural uses of this chemical, but in response to President Obama’s National Pollinator Strategy, and recent scientific studies by the State of California, has released a “preliminary pollinator risk assessment” that imidacloprid use potentially poses risks to bee hives. This assessment focuses on agricultural crops and does not consider this chemical’s risks to bees when used on ornamental flowering plants!

Chemical companies that produce this chemical insist that bees are not at risk when this company is used correctly.

The EPA is inviting feedback during 60-day comment period. It is continuing assessment of the risks of this chemical and three other neonics, with more findings to be released in December of 2016.

Irrigation for a Small Greenhouse

Another rainy day project in the garden!

Several years ago, with the help of a friend, I installed a greenhouse in a corner of my garden. This is a typical backyard structure, just ten-by-twelve feet, not an expansive “plant factory” like those on the annual open greenhouse event hosted by local nurseries for mostly flowers.

Greenhouse-large

My greenhouse, although small, has ample bench and shelf space for an ambitious program of propagating and maintaining plants. Plants will assume the primary role of growing, and a greenhouse can easily exclude deer and gophers, but operating a greenhouse still requires investments of the gardener’s time for planning, planting, monitoring and controlling climate, diseases and the smaller pests.

Best intentions aside, other priorities can leave the greenhouse unattended. When that has happened to me, my plants have tended to expire.

In addition, my greenhouse developed another problem. I had installed a sprinkling and misting system to irrigate the plants, using an inexpensive battery-operated timer. It worked fine until the battery died when the irrigation valves were open. The timer did not have the power to close the valves, so they ran for days, unobserved. This resulted in soggy plants, a huge water bill and attendance in a water conservation workshop.

I turned off the system in favor of watering by hand, but because the greenhouse is away from the house, it was easy for me to neglect the watering schedule. Except for some succulents, my plants did not do well under that plan. A clear need existed for a reliable automatic irrigation system.

Working with another gardening friend, we are installing such a system, with the longer-term objective of starting seeds, growing new plants to garden-ready size, and maintaining surplus plants for giving to other gardeners. (I could also grow plants for sale, but the small-scale nursery business would seem uneconomic.)

The irrigation system includes a professional grade controller, capable of scheduling four irrigation valves, and two valves plus capped connections for two future valves. Wires running the length of the greenhouse support flexible tubing over plants, which will be on tables or shelves (not on the ground). The tubing will have multiple emitters that will either spray or drip water on the plants. Spray is best for groups of seedlings or small plants while drip is more effective for larger plants.

Some gardening friends use their greenhouses to maintain collections of succulent plants that require warm, dry conditions, or orchids or other tropicals that require warm and moist conditions. Greenhouses in public gardens often focus on one or the other of these plant groups.

When planning a greenhouse for the home garden, a good first step would be to decide which plants are to be grown, and what climate those plants will need: cool/moderate/warm, or dry/tropical. To learn about these options, search the Internet for “types of greenhouses.”

My greenhouse is intended to moderate temperatures, year-round, and to control moisture levels through scheduled spray and drip irrigation. This growing environment will support a wide range of plants, excluding only those that require extreme conditions. Plants that require a winter chill, for example, grow poorly in the coastal Monterey Bay area, whether in a greenhouse or in the ground.

The home gardener can use a greenhouse to extend the growing season, protect against larger pests, and control the environment for either specialty plants or general gardening. Greenhouse management can be an engaging and satisfying form of gardening; it can also be more expensive and time-consuming than conventional gardening. Enter with eyes wide open.