Growing Good Food in Bad Air

It is Thursday, October 1st and the air in SF is filled with smoke again today, as it has been, off and on, for weeks. While I am glad not to be in the path of a fire, the smoke pollution is disturbing. Most of news coverage of the pollution concerns its effect on human physical health, which is, of course important. Air pollution causes lung inflammation and reduces our lung capacity. It is particularly dangerous for older people and children. Now, as the coronavirus is on all of our minds, and some of us try to go out less to reduce the chance of infection, the smoke is more disturbing than ever because it reduces our chance for outdoor exercise. For more on human health effects, see Washington Post on air pollution harm to health

While we need cloth masks now, due to the coronavirus emergency, I have learned these do not protect against air pollution. The only protection is an N95 mask or an N95 respirator mask, which most of us do not own.

Gardeners have special concerns. First, we are hesitant to garden in this bad air. I wanted to check apples for ripeness and harvest some that are ripe today, but may not do it as I look out the window and use online sources to confirm what my eyes tell me. Last month I was two days late in watering my community garden. (Fortunately, I didn’t lose any crops, but some of my lettuce was starting to droop.)

I have also had two questions concerning the plants I am growing. The first is what air pollution is doing to them, the second is whether they are safe for me to eat. The answer to the first question is that the effects of air pollution are not good—more on this in a minute. The answer to the second question is one of the only bright spots in my research: pollution does not affect healthfulness of a crop. If the food you harvest has ash or grime on it, wash it off. For good measure you can agitate it in a tablespoon of vinegar in 6 cups of water, then rinse it in plain water. (White vinegar is fine—no need for anything fancy.) You can’t wash off other smog, but plants damaged by it are perfectly safe to eat.

1543 Ash on tomato leaf

White ash on tomato leaf in late September of 2020. I washed it off to let more light in. (Tomato leaves, which are not edible, are hairy, so they trap more ash than smooth leaves would, or than the smooth-surfaced tomato fruit.)

Back to the effect on plants. Days of smoky air and falling ash will result in a coating on upper plant surfaces. The main effect of this is reduced photosynthesis, since less sunlight can reach the chloroplasts. This will reduce growth of the plant. After a bout of smoky air, it’s a good idea to hose down your garden plants to knock the stuff off of them.

Worse for plants is the more common components of smog, such as oxides of nitrogen or lower atmospheric ozone. (Unlike the ozone layer in the upper atmosphere, ozone near the earth surface is harmful.) These and other polluting gases can enter the chambers in leaves where the plant carries out photosynthesis and interfere with the chemical process. Ozone is particularly harmful. At best, pollution damage will slow the growth of plants. They will make fewer leaves, and will have a smaller root system. This means our food crops won’t produce as much food or as produce it as fast as they would in clean air. At worst, susceptible plants will show symptoms, starting with tiny dead spots on leaves and progressing to dying older leaves. Susceptibility varies among crops and varieties of specific crops. Peas and beans and leafy crops are generally most susceptible, and one study found summer crops more affected than cool-season crops.

            (Please note that we are here thinking about pollution of the air, not the soil. If you are worried about soil pollution, you should have it tested for lead and cadmium, and follow the lab’s instructions for what you can grow in it. Also, don’t grow food in a garden that is immediately adjacent to a busy road, especially where vehicles often brake.)

When it comes to air pollution, there is another concern that we should be aware of. When air pollution prevents a plant from photosynthesizing, either by blocking sunlight or interfering with the chemistry of the process, it will reduce the amount of CO2 that plant is removing from the air. This means that pollution-challenged plants are making our excess atmospheric CO2 problem just that much worse. It means that air pollution creates a negative feedback loop, making global climate change happen just that much faster.

Happily, we can safely eat and enjoy any food we succeed in growing in our gardens in polluted air, and are probably not so dependent on our garden that the little bit less production is a problem, but remember agricultural production is also threatened. Our understanding, as gardeners, of what increased air pollution means, not only for humans, but for plants, gives us an early distant warning, and more reason to act, and encourage others to act, to reduce the pollution of our air.

Where and when is air pollution a problem?

Large urban areas across the earth have bad, sometimes chronically very bad air, but it is also a problem in many places we think of as “pristine.” So, for example, Denver has a problem, but so does Rocky Mountain National Park.

One of the worst pollutants is lower atmospheric ozone (O3). It forms when oxides of nitrogen and volatile organic compounds (VOCs) interact in sunlight. The warmer the day, the more ozone forms, so it tends to be worst in afternoons and later in the summer season (just when we are counting on harvesting summer crops).

Where do the components of air pollution come from:

--Well, obviously from fires. And one of the scariest results of recent fires has been the understanding that when modern structures burn, not only is it a horrid loss to the owner, but some of what is released into the air is toxic compounds from the many synthetic materials we use today in building, furniture, and other objects in our homes.

--The biggest other sources are electricity generation (if the plant doing the generating is coal or petroleum-fueled) and gasoline-fueled transportation.

--Agriculture and industrial processes add some to the mix. One study, in Colorado, found that plants making fabrics added significant pollution, because it used petroleum as a fuel and because polyester is a petroleum product.

--Volitile organic compounds (VOCs) come from products like paint or paint thinner, asphalt, oil and gasoline.

What can we do to reduce air pollution:

--Drive less, keep your car well-tuned, keep tires inflated properly, and buy automobiles that burn less gasoline—fuel efficient, hybrid, electric.

--Avoid idling car motors unnecessarily.

--Avoid using other gas-operated motors as much as possible—for example by using an electric lawn mower.

--Avoid using products that add VOCs to the air. Check paint cans and labels of other suspect products for an indication that they are VOC-free.

--Avoid toping off of gasoline tanks when filling them at a gas station. (When you smell gas, it is going into the atmosphere.)

--Do yardwork that might add to pollution in the evening, so pollutants can dissipate before the warm part of the following day.

--Try to reduce the amount of petroleum-source materials you use in your life, for example plastic, polyester in clothing, synthetic fertilizers and pesticides. Eliminate their use if you can, reduce, reuse, and recycle if you do use them.

--Spread the word about what causes air pollution and encourage others to reduce their contributions to it.

Here are two links you can use to learn more:

To check air quality: purpleair.com. Zoom in on specific locations using their world map.

To learn about ozone gardens that assess damage to plants, watch a video on ozone pollution and a lecture by a researcher who studies ozone damage:  Ozone Gardens and Ozone Pollution


Spring Bloom in Fall--It's a Problem

In today's SF Chronicle (January 1, 1917), I wrote about plants that bloomed last fall in San Francisco that ought not to have been blooming until spring, caused by continuing climate change.

While it's true that we typically have our warmest "summer" weather from mid-September to mid-October, this weather has been lasting longer than usual. Last fall, the warm days and mild nights lasted until near the end of November. We celebrated time spent outdoors in nice weather, but some of our garden plants reacted by blooming and leafing out as if it were spring. This is a problem for the plants, which put energy and physical matter into doing this, so that when spring really does come, they have less stored matter and food energy to do it all again. This weakens the plant, leaving it more susceptible to all kinds of setbacks.

Case in point is my apple tree, which has borne bountiful crops of delicious apples for 30 years. But recently it has been trying to bloom in fall. Then, because winters aren't quite cold enough, it blooms later than usual in the spring. And, because of the energy it used up in fall, it blooms more sparsely. Two years ago, it had practically no fruit.

Last year it did better, though not as well as it used to do. The photo below, which I sent to the Chronicle, but they didn't use in the paper, shows my tree last November, with a few last apples and last leaves till hanging on while blooms and new leaves opened all around them. Now, on January 1, all the new leaves have succumbed to cold, wasting all that effort.

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If you are growing other temperate plants in the Bay Area, such as cherries and plums (ornamental or fruiting), magnolias, lilacs, or azaleas, you may be having the same kind of problem. What's to be done to save our plants? Obviously continue to work against climate change, a movement in which California in general is doing well.  But we can also join an effort to record the changes, in which our regional data will provide extremely valuable evidence.

More data about how climate change is affecting plants in our region is especially important so that we are represented in a system that has so much more data from cold-winter regions.

There are two organizations that are seeking citizen science data. One is the National Phenology Network (www.usapn.org/), sponsor of the National Phenology Project. It studies both plant and animal species. Another, Project Budburst (budburst.org), is studying only plant responses. Phenology is the study of what plants and animals do in response to seasonal changes.

Sending records to these databases is easy to do online. Log in, choose a plant, and tell them what it is doing on various dates. Children can do it at home and school classes can do it. Both web sites have curriculum information to help teachers fit the work into classes. It teaches observation, appreciation of plants, climate science, ecology, and how science is done

So as our new, and rather unnerving, year begins, please help observe and record what is going on with nature. Your reports will be powerful.


Overwintering Vegetable Crops: Seed Sources

California gardeners who live in mild winter climates (all but the Sierra foothills and mountains), can grow overwintering types of broccoli, cabbage, and cauliflower. We may also be looking for varieties of some other crops that grow well in our winter months. For example, some lettuce varieties handle cold better than others. In addition, if you live in a coastal part of California, you will want to locate vegetable varieties that will thrive in cool summers. For the widest choice of varieties, you can start them from seed.  In my book Golden Gate Gardening, I have described many of the best overwintering and cool-tolerant varieties, given sources for seed, and included a chapter explaining when and how to start seedlings. Following is a short list of some of our best mail order seed companies for regionally adapted varieties, and two local stores that sell seed from some of these otherwise mail order companies.

Yr frost 0299697-R01-008 copyOverwintering 'Purple Sprouting' Broccoli

Bountiful Gardens  Bountiful Gardens Web Site

Kitazawa Seed Company  Kitazawa Web Site

Niichols Garden Nursery   Nichols Web Site

Territorial Seed Company  Territorial Web Site

Two East Bay stores offer seeds from some of these seed companies:

Pollinate Farm and Garden, 2727 Fruitvale Avenue, Oakland, 510-686-3493

Berkeley Horticultural Nursery, 1310 McGee Avenue, Berkeley, 510-526-4704

 

 


Some Resources for Waterwise Gardeners

This is not meant to be a complete list, by any means, but here are a few publications and links that will be useful if you are selecting plants for a waterwise garden.

WUCOLS stands for Water Use Classification of Landscape Plants. This project, sponsored by UCDavis, California Dept of Water Resources, California Center for Urban Horticulture, lets you find out the water needs of over 3,500 landscape plants in six different regions of California. The most recent version WUCOLS IV,can be accessed at the following address:

http://ucanr.edu/sites/WUCOLS/   Click on "Plant Search" Or you can use this link: WUCOLS IV

For information on growing California Native Plants, check out the Las Pilitas web site, laspilitas.com, or use this link: Las Pilitas Nursery.

Here are links to two articles on the subject of watering trees during a drought that were recently in the San Francisco Chronicle:

Trees Out on A Limb

Watering Trees in A Drought

Finally, here is a short list of books that you will find useful as you seek ideas and plants for a waterwise garden:

California Native Plants for the Garden, Burnstein, Fross, O'Brien, Cachuma Press, 2005.Photos, text on garden uses and care.

New Sunset Western Garden Book. I think the most recent is 2012, and it does have all color photos, which are helpful, but the text of couple of editions right before this one were a little more thorough.

Plant Life in the World's Mediterranean Climates, Peter B. Dallman, University of California Press, 1998. Maps and charts show how the 5 mediterranean regions are similar and, importantly, how they differ, then explains the habitats to which many of our favorite plants are adapted.

 Plants and Landscapes for Summer-dry Climates of the San Francisco Bay Region, East Bay MUD, 2004. Inspiring photos and useful information.

The Random House Book of Indoor and Greenhouse Plants, Roger Phillips & Martyn Rix, Volumes 1 & 2, Random House,1997. Despite the name, thiese two volumes cover mostly mediterranean and other subtropical plants that we can grow outside. The photos and text about the plants in their native habitats are very useful.

Wildly Successful Plants: Northern California, Pam Peirce, Sasquatch Books, 2004.California garden history, plant origins, garden maintenance instructions, garden design, and a philosophy for a regional garden.


Windbreak for a Garden

My column in today's San Francisco Chronicle was shortened, removing information about using shadecloth to create a windbreak for a garden. It might be a useful solution, especially for a garden on a roof or elevated deck. Today's column is about growing plants on a windy deck, in containers. The reader wanted to know if there are plants that are both drought tolerant and also attractive to pollinators. Indeed there are, and I listed some, but it is also true that bees and butterflies will be less likely to visit if the site is quite windy. 

The following information was cut from my column:

*******************

Reducing windiness on your deck would not only reduce water loss, but also produce an environment more inviting to bees and other pollinators. While a wooden lattice on the windward side would help, I once wondered if there is a wind blocking cloth. I learned that the best material available is a polyester shade cloth that blocks about 50% of the sunlight. If it blocks less sun, it won't stop much wind, so it's a compromise.

            You wouldn't want to put either up on the south side of a garden, or you'd have a shade garden, but our region's prevailing winds are from the west or northwest. A north side wind calming structure wouldn't block the sun, while a west side one would be a trade-off between afternoon sun and wind. You'll have to be the one to decide if that's more help than hindrance in your situation.

            Charley's Greenhouse (charleysgreenhouse.com, (800) 322-4707) sells a 6-by-12 foot, knitted, green, 50% shade material with edging and grommets for $52.00.

 


More Late Summer Bloom for San Francisco

I've been writing about flowers that bloom in my garden in late summer and fall. This time of year is always a challenge, because the summer is dry and so many mediterranean and California native plants bloom earlier in the year. I have the further problem that my garden is in a foggy and cool part of the city, and the backyard goes into shade in fall and winter. This results in outbreaks of powdery mildew diseases and gray mold. So I am writing about plants that resist these diseases.

The photo below is of pineapple sage, Salvia elegans, which provides reliable color, from September into November. The photo was taken on October 15th. November 15th, it was still in bloom. The spot where it is planted is in sun from April until September, then in open shade, so it gets the sun it needs to prepare to bloom.

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This plant attracts hummingbirds and offers a whiff of pineapple to gardeners who brush against it. The edible flowers are attractive in salads, especially in a fruit salad. The leaves have such a tantilizing scent, but unfortunately, do not hold the scent when they have been cooked.

In winter, pneapple sage loses most of its leaves. In spring, I cut back any bare stems, and new, leafy ones grow to replace them.

Another late-blooming flower with tubular red flowers is the California fuchsia. (It used to be called Zauschneria californica, but has had a botanical name change, so it is now to be called Epilobium canuum.) I grow it in a place that gets sun all year, but it could handle winter shade, since it is mostly dormant in winter. You wouldn't want it too near to a pineapple sage plant, in any case, since one small, red tubular flower in a small space is enough.

California fuchsia blooms from July onward into autumn. This year, following our spectacularly mild November, some parts of the plant are still blooming at the end of December. It has no scent, however it does share with pineapple sage that it attracts hummingbirds. It has no scent. The other morning when I went to pick up the paper, a hummer was taking its breakfast in the California fuchsias. 

The main drawback I have found to California fuchsia is that the plant is very brittle. If a cat fight happens in it, or you have to reach through it to get to other plants, the meter reader has to push it aside to read a metor, damage will occur. Pieces will break off and have to be discarded. So be careful where you put it.

After California fuchsia blooms, it looks pretty ratty and you will want to cut it back. Maybe the first year just cut back partway, but  I cut my established plants to near the ground and it comes back fine.

  Zausch September 2010 020 copy

Zausch September 2010 023 copy

For some bright yellow in late summer and autumn, grow goldenrod. There is a native species, Solidago californica, which I think is the one in the photo. These plants are about 3 feet tall and were covered with bees--honeybees, bumble bees, large and small native bees--they were all having a feast.

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Here is a big bee, probably native, not a bumblebee.

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This one was a wee little bee, probably another native. After goldenrod blooms, cut it back partway. It is a semi-evergreen perennial. And, by the way, it is falsely accused of causing hayfever. Apparently it is the ragweed that blooms at the same time as Eastern goldenrod species that is the culprit.

GR sm bee IMG_5417 copy

Coming up: Some flowers for winter color.


Pineapple Lily--Flowers for Late Summer in San Francisco Gardens

My San Francisco garden is often foggy, cool, and damp in the summer, too much so for a number of late summer-into-fall kinds of flowers. I'm starting a series of posts about some plants that bloom in my garden in this season without succumbing to botrytis (gray mold) or other diseases encouraged by the cool, damp microclimate.

This first flower is Eucomis, also known as pineapple lily. I like it because it looks so dramatic, but it is easy to grow. I have grown it in containers for many years. It blooms without fail in mid-August and lasts several weeks. The leaves are low to the ground; the flower stem is over a foot tall.

Eucomis IMG_4098 copy
This plant is Eucomis comosa, which has white or pink flowers. Eucomis cl IMG_5021 copy
Here's a close up of one that has pinker flowers. You can see they are like miniature lilies. It is indeed a lily relative, but not related to pineapple. That name comes from the little tuft of leaves at the top of the flower stem, like the one above a pineapple.

Eucomis grows from bulbs, which you may find at a local nursery in the spring, or may have to mail order from a bulb specialty company. It can be grown in the ground if you like, or you can plant one or more bulbs in a container. In the ground or in a container, plant so the neck of the bulb shows at the surface.The plants are hardy to 10 degrees F.

Though the porch on which they are growing goes into shade while the Eucomis is still in bloom, becoming even more cool and damp, it never becomes infected with botrytis or any other disease. After it blooms, the flower stems and leaves pull out of the bulb easily and can be composted.

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Here is a group of eucomis plants in several containers. The ones in the back right are Eucomis bicolor, a similar species that has pale green flowers with purple edges. This species has the same growing needs as E. comosa.

 


Some Plants Think it's Spring this November!

Well, we know they aren't thinking, and I guess that's the problem. When San Francisco has some cold weather followed by a period of warm days in mid-Autumn, some plants start growing, or blooming, as they would normally do in February or later. We see a few plum blossoms in fall sometimes, but this year I am seeing many blooming plum trees. I even saw a blooming crabapple tree yesterday, and they normally bloom later in spring than the flowering plums!

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Looks like spring, doesn't it. But look enlarge the image and you see the fake spiderwebs on that tree that remain from Halloween. This shot was taken on November 15, 2012.

In my backyard, I cut a bulbous iris and put it in a vase in early November. This is definitely a February flower, but three plants have bloomed and the rest are all and still growing.

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You can see one of the last ripe apples still hanging on our tree. Wrong time of year for iris, for sure.

Another plant reacting badly is the Crocosmia 'Solfaterre'. It had its deep yellow flowers in September, then died back, and I cut it to the ground. Didn't expect to see it again until maybe March. But here it is again, with leaves popping up in November! (The leaves start out green, but turn a smokey brown by midsummer.)

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The problem, for these and other early growing and blooming plants is that they are using up all of this energy now, and will probably be forced back into dormancy by colder weather in December and January. Thus they will have less energy to grow and bloom in the spring.

Global warming may change what we can successfully grow here. Some plants that depend on just enough winter chill to rest and regrow, may not thrive if our climate shifts just enough to make them try to bloom twice a year.

The study of the relationship between climate and natural phenomena such as flower bloom time is phenology. We're going to hear a lot more about it as the earth warms!

I was out gardening today, making Black Friday into a green one. A peaceful day. I deadheaded the Cosmos, which are still blooming madly in both front and back yards, then cleaned up apple leaves under our tree, to get rid of apple scab spores. Tomorrow I'll put some composted chicken manure on the wild onion (Allium triquetrum) bed to help them get growing faster. I've been watching the madness at stores on TV and being glad to be home today.

 

 


Healthy Schools Information

I am giving some classes about pest management for some school garden coordinators in San Francisco. Because of this, I have been researching the legalities of pest management in California schools. Below are some links to information that explains the Healthy Schools Act, including lists of pest management chemicals that can be used in schools without posting, and explanations of how to post use of a chemical that isn't on the list.

Note that the rules were set up mainly for inside and landscape usage, rather than for food gardens. The active ingredients that are exempted from the Healthy Schools Act are all basically food products, so are permitted in food gardens, but there are inert ingredients that aren't, so to find out which these are, see the EPA list of inert chemicals that can be used in "food use sites". (Pesticide labels also indicate whether the product is legal to use in food gardens.)

http://apps.cdpr.ca.gov/schoolipm/   This is the main page of the CDPR School IPM Program. It provides overall info on regulations that  apply to schools, and allows you to link to the next two useful pages: 

http://apps.cdpr.ca.gov/schoolipm/overview/hsa_faq_color.pdf  This document provides FAQs on the Healthy Schools Act.

http://apps.cdpr.ca.gov/schoolipm/school_ipm_law/exempt_products.pdf   Here you can read about Pesticides & Inert Ingredients that are exempted from the Healthy Schools Act (The actual lists start on page 3--scroll down) (This document also includes links to the EPA minimal risk pesticide list and to the list of CDPR exempted products) 

http://www.epa.gov/opprd001/inerts/section25b_inerts.pdf  This is the list of inert ingredients permitted for use on food crops.

www.cdpr.ca.gov   To see if a pesticide is registered (legal) in California (Click on: Look up pesticide products.)

www.npic.orst.edu. Use this site to research a pesticide ingredient through the National Pesticide Information Center, sponsored by the EPA, go to  Look for Active Ingredient Fact Sheets.There are technical or general Information Sheets, depending on your interest and technical background. There are also sheets on inerts and much other useful information on this site. You can also call them to ask for information in person.

www.ipm.ucdavis.edu  Click on Home and Garden Turf and Landscape, then on Pesticide Information, then on "Home & Landscape Active Ingredients Database." Also, within the pest management writeups, there are comparison charts for various pesticides, telling you what parts of the environement they might harm and other health and environmental factors you might consider when choosing among alternatives. 

See also my book, Golden Gate Gardening. The chapter on IPM includes much information about choosing and using pesticides. In addition, the book's Appendix IV, pages 390-397,  explains pesticides in greater detail, including how to read a label and detailed analyses of common active ingredients you may be thinking of using in your garden, so you can make informed choices among your options.


Cucumbers in December?

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If you have any doubts that this has been a mild fall in San Francisco, consider this: I shot this photo of a plump cucumber in my garden on December 23rd! Although the leaves are dying, a few are still green and the cucs, though small, keep coming. They are also deliciously tender, crisp, and sweet. They received rave reviews in a large Christmas salad we made for a potluck.The plants tell us about the weather as surely as do the thermometor and the rain guage. I think the reasons for this ongoing success are both the mild temperatures and the lack of rain.

How unusual is this late harvest? I've been growing this variety of cucumber, 'Burpless Tasty Green', in the same San Francisco garden for maybe 30 years, and this is the first time they have borne this late. Usually, I pick the last of them by early to mid-November. This year, not only did I pick 3 cucs on December 23rd, but 2 more small ones on December 30th!.

The harvests from a winter garden always seem like special gifts. Hope yours is providing some for you as well--and Happy New Year!