Some Soil Basics--Soil, Potting Mix, Amendment, Compost

What is soil? What is potting mix? What is Compost? When to use each and why.

Soil contains 5 ingredients: Mineral particles, water, air, living creatures, and dead organic matter. What plants need to get from soil is: minerals (from dead organic matter and sometimes from the mineral particles), water, oxygen (because every living cell respires, using the air’s oxygen and releasing its carbon dioxide), and sometimes symbiotic relationships with living creatures (such as mycorrhizae—which rarely need to be purchased).

The mineral particles in soil range from tiny clay particles to the larger sand particles, with the in-between-sized silt particles. The best for plant growth is a mix of the three, with more sand than the other two, such as sandy loam, though other mineral particle proportions can be improved by adding organic matter.

The nutrients plants need to get from organic matter are largely nitrogen, phosphorous, and potassium, which are released from dead organic matter as it is digested by soil creatures, including soil-dwelling bacteria earthworms, fungi, and actinomycetes. Plants don’t need the complex molecules of organic substances, just the simple elements.

In nature, organic matter enters soil when plants or animals die or when animals urinate or leave manure. Most organic matter falls on the surface, then earthworms and other creatures carry it underground. Burrowing animals also produce some organic matter when they die or defecate underground, though animal burrows are also relatively near to the surface. Nutrients from this organic matter seep deeper with rainfall or artificial watering and are also left behind in deeper soil when plant roots die there. In nature, plants expect a gradient between the amount of nutrients from organic matter and the amount of oxygen, from greater amounts at the surface to lower amounts in deep soil. (There are fewer living creatures in deep soil, simply because there is less oxygen, so if organic matter is down there, nothing will digest it to provide plants with nutrients.)

Organic matter helps the soil hold onto more water longer and still have air spaces. All organic matter provides some nitrogen, phosphorus, potassium, and trace minerals. Not all organic matter is rich in nitrogen, which is the nutrient most likely to be low in local soils. For growing vegetables, we want to add more nitrogen than, say a for a shade tree or an ornamental shrub, because we want vegetables to grow big and grow fast. Some organic materials are so low in nitrogen that soil creatures will not be able to digest them unless they also use some nitrogen from other materials in the soil, such as nitrogen fertilizers we have added. Low-nitrogen organic materials include sawdust and shredded bark. These are high in complex plant carbohydrates, such as cellulose or lignin, for which we use the shorthand “carbon.” Others are high in nitrogen. If an organic material does contain plenty of nitrogen, we consider the organic matter to be fertilizer, however we need to be careful not to use too much of high nitrogen materials, since they can burn plant roots.  

When we consider organic matter for adding to soil, we speak of the carbon/nitrogen or C/N ratio. Ideally we want to dig in some organic matter that is about 30/1. This will improve the water and air capacities of the soil as well as providing nutrients. The C/N ratio of sawdust or shredded bark is in the range of 200/1 to 700/1. That of garden wastes is 25/1 to 80/1, depending on whether it is fresh and green or dry and fibrous. That of kitchen scraps is about 17/1 and fresh animal manure is also quite nitrogen-rich. A good way to balance these widely varying materials is to compost them—mix them up and let them rot together for a while. Ideally, we’d mix materials to aim for a finished C/N ratio of 30/1. (We call mixtures of aged organic matter compost no matter what the end C/N ratio might be, but what went into it will determine how high the nitrogen content of the finished product can be. When a compost is made of only garden waste, which is modest in nitrogen content, you probably will need to dig another source of nitrogen into your soil as well.)

If you want to increase the organic matter in your soil, buy materials that are labeled “amendment” or “compost” and dig a layer into the soil surface along with any fertilizer you might be using. (You can also spread organic materials on the soil surface as a mulch. For vegetables you want to use s small-particled mulch, or something that will decay relatively fast, not big bark chunks that must be raked aside before you can replant.)

Potting mix, container mix, landscape mixes and similar products are often labeled “soil,” which they are not. They most often get their bulk from sawdust or shredded bark, that low-nitrogen stuff. (And plants don’t really need that much organic matter of any type. Three percent is usually plenty.) Potting mixes may also contain mineral particles that are inert or nearly so as far as the plants are concerned, such as perlite, pumice, or even pea gravel. They may contain small amounts of aged manure or worm castings, which is a good thing, but which does not make them adequate to use as garden soil. They are typically sterilized, so as purchased they do not contain any living creatures. This is fine if you are growing houseplants, but not ideal for garden soil. They may also contain chemical fertilizers or even pesticides—read the label carefully.

If you need to fill an empty garden bed or raise the soil level in your plot significantly, the best idea is to raise it using plain soil, such as sandy loam, then dig some compost and, if you like, other organic fertilizer, into the top 6-8 inches of the soil. (or you could stop adding soil at 8 inches from the top, dig a couple of inches of compost in, then add 8 more inches and dig in twice as much compost as you just did.) This imitates nature, in that the bed will have more organic material and higher fertility near the surface, less deeper in the soil. . (If you are making a Dearborn garden bed much deeper than it was, or just adding soil to raise its level in the bed, it would be best to take out the old soil, which someone has been amending and fertilizing for years, add the fresh sandy loam, and then put the old soil back on top, and then dig in some amendment and fertilizer.)

Potting mix or container mix are best used in a container 2 feet or less deep, the kind with one or a couple of holes for drainage. They are great for this use, water-retentive and providing good drainage. However, after a while, container mixes collapse. This is when the wise gardener will repot the plant in fresh mix. Potting or container mix are not designed for beds with bottoms open to the soil, or for any use that is over 2 feet deep. When a potting mix is used in a deep raised bed, a problem will ensue in a year or two when the stuff collapses.  The plant roots will then lack air, and the bed will need lots of fertilizer to supplement the carbon-rich wood products that remain. The gardener may spend a lot of money adding more potting mix and fertilizer, or dig it out and start all over with fresh potting mix or, better idea, soil. There are so many names of products sold in bags now that it becomes confusing, but if you stick with potting mix for containers two feet or less deep, and, for garden beds open to the soil beneath them, use soil with organic matter (well-made compost, soil amendment, maybe some extra fertilizer) dug into the top 6-8 inches, you can't go wrong.

I explored the web site of Lyngsø Garden Products (in the SF Bay Area) which is where we have obtained the turkey manure-based compost for the past couple of years. They sell sandy loam, and have a very nice explanation of what it is and what it’s for. They also sell many other “soil” products. I noted that some of them were a lot cheaper than sandy loam—probably because they contain so much sawdust or shredded bark. They also sell Organic Diestel Structured Compost, the turkey-manure-based compost. It’s very pricy, and worth it I think. Lyngsø sells by the bag or will deliver as little as a cubic yard of material for a flat fee of $85. They are in San Carlos. 

Now let us consider for a minute how volume of these materials is calculated. Soil, amendment, compost, etc. are sold by the cubic foot or cubic yard. Bags of soil, compost, etc. for outdoor use contain 1 or 2 cubic feet. Any more and you could not lift them. There are 27 cubic feet in a cubic yard (3’ x 3’ x 3’).

A bed that is 8 x 8 feet and 2 feet deep requires, as an example, 128 cubic feet, or about 4.74 cubic yards of soil to fill, or a bit less to give yourself headroom and room for some amendment, say about 4.25 cubic yards.

A final tip: When adding a material different from what is below it, it is always wise to add a layer a few inches thick first, and mix it with the layer below it, then add the rest. This avoids having an abrupt transition, which water may not readily pass through.

At Lyngsøgarden.com:

Sandy Loam is $62.00 a cubic yard, $3.50 /sk (sk, for some reason, means cubic foot bag)

Organic Diestel Structured Compost is $145.00 a cubic yard, $6.50 /sk

Note that the information about filling garden beds with soil, not potting mix is also explained in the soils chapter of my book Golden Gate Gardening,


Garden Tip

Got Pests? Try Botanical Oils

            Into every beautiful and productive garden a little nasty pest activity may fall. Aphids may infest the kale, powdery mildew coat the leaves of zucchini, black spot mar the rose leaves, or little white flies flutter while their nymphs are sucking the sap from a shrub.

            In the early days of modern pesticides, incredibly toxic chemicals were sold to home gardeners to manage pests. These days, the products we use are more likely to kill pests without threatening our health as well. A good example is oil-based pesticide.

            Petroleum oil in water, with a sticker-spreader to keep it from settling out of solution, was long used to spray woody plants in winter. It was called “dormant oil.” If you sprayed it when leaves or flowers were present, it burned them. Because of this, other, often less environmentally friendly, chemicals were used in the summer.

            However at some point, researchers learned that it was sulfur impurities in the petroleum oils that made it toxic to leaves. So they refined the sulfur out and sold the new products as “superior” or “summer” oils. You could safely spray them on leaves and flowers all summer, as long as the temperature was below 90 degrees F when you sprayed.

            Oil kills by clogging the breathing pores of insects or actually exploding the spores and other cells of fungus. And as research continued, It was found that many kinds of botanical oils will also do the job. Products based on oil of canola, soy, linseed, sesame, even jojoba (a desert plant) began to appear (read the active ingredients list). Some of these sprays include aromatic oils, such as thyme and peppermint, which might offer some repellant action.

            I encourage you to try these products, based on renewable, even edible, oil sources, in your garden. I have permanently stopped an aphid infection of kale with a single, thorough spray of a botanical oil product. However it is usually necessary to respray every week or two to continue the protection. Also, to control diseases, oils are most effective as a preventative or at the very first signs. If you spray early, you can kill spores on plant surfaces, but once a fungus grows deep inside the plant, where sprays can’t reach, it is often too late. Follow directions on labels and watch your plants.

            Another oil product that kills insects and some disease spores is Neem oil. It also is toxic for insects to eat and kind of disgusting to them, so reduces feeding and even egglaying. However, the ingredient, azadirachtin, is a growth retardant for bees, so I prefer to try other oils first, or save neem oil for pests not listed on labels of botanical oil products. Azadirachtin breaks down in sunlight in 100 hours. Follow directions on label, including about interval between spraying food crops and eating them.

           


A New Protector Against Burrowing Animals

This spring I found that a burrowing animal was eating plants, roots and tops, in my small front garden. I know it was not a mole, because moles don't eat plants, just insects and earthworms. Could have been a gopher, but by the amount it ate in a night, I thought maybe something smaller, maybe a RAT! (The rats that burrow are called sewer rats; the ones that don't, roof rats. Rats have burrowed in my backyard before so this seemed a good guess.)

Whatever it was, my Chinese forget-me-nots, the ones I grew lovingly from seed and transplanted into the garden, were disappearing night by night. Then whatever it was started in on the primroses I just bought and set out, and the large 'Moonglow' yellow yarrow was losing branches, then roots. Then it ate most of the tops off of two x kellereri yarrows!  These were divisions of my original plant-which is one of my favorites. Something had to happen.

I dug out all of the yarrow, both 'Moonglow' and  Kellereri, and what was left of the primroses and put them all in pots on the back porch. Then I cleared away and found the place the varmint had blocked up the opening of its burrow. I dug it out, exposing the hole. The varmint had replugged it the next morning. I repeated. It repeated. I repeated. After many repeats, over several days, I decided I had to escalate. I have heard that water down the burrow can discourage a burrowing pest, but doubted it in a large garden, but in my 10 x 12 foot front garden, maybe it would work. I wanted to tell the varmint that this was not a good place for a home, before it ate everything left there. At this point about a quarter of the tiny space was a wreck. My husband was beginning to ask whether maybe I should be looking for a trap. I said hold on, let's see if this works.

So, the next day, I dug the plug out again, got the hose, attached a jet nozzle, and put it down the hole. Turned on the water. Most of it stayed in the hole. But the next say, the plug was back.

Over the course of a week or so, I dug out the burrow plug 8 or 10 times, used the hose 3 times. And then the varmint stopped replugging the hole. 

During the battle, I decided to replant a couple of plants in gopher baskets. And here is where my problem led to a discovery that will be useful to other gardeners. When I went over to San Francisco's Flowercraft nursery, they offered me a new kind of basket, made of a soft stainless steel wire mesh. So this is what I have used, and have written about it in my May 8th, 2016 SF Chronicle column.They are called Grow Master Baskets. To learn more about them and see who sells them, see westernplantingsolutions.com or call 530-751-3366.

These baskets are less expensive than the old kind, easier to handle, and come in many sizes.  The company suggests fitting a basket over the rootball like a glove, but I have used baskets that are a bit larger than present rootballs, spreading the baskets in a wider planting hole, and putting some soil in them, then setting the plants in the soil.That way the plant has room to grow more roots and still be protected.

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'Moonglow' yarrow plant in a Grow Master anti-gopher basket

When I first used the basket, the varmint was still active. Because I had used a somewhat larger basket than the rootball, there was enough of it to roll up over the plant and secure with some plant-tie that I ran through some of the openings in the mesh. This protected the top of the plant as well as the roots while it got re-established, and while I figured out what to do next.

But now I have uncovered all of the protected plants. The 'Moonglow' yarrow is about to bloom. The x kellereri yarrows are still recovering in pots, but they shall return. And one Chinese forget-me-not survived to bloom beautifully!

 

 


Peppers Leafing Out After Winter

In the post I wrote about Peridot pepper, I said it was not leafing out again in spring, and that I thought it would not be a perennial plant in San Francisco. But perhaps I spoke too soon.

As background, I should say that even common garden peppers, the ones in the species Capsicum annuum, are perennials in a tropical enough climate. I have overwintered them in San Francisco. They lost their leaves, but did leaf out moderately well and bore a small crop the second summer. They were not as productive as in the first summer, and since in San Francisco, they weren't hugely productive the first year, I decided overwintering them wasn't worth the trouble.

One species pepper is fully perennial here. That is the rocata pepper, in the species Capsicum pubescens. It keeps almost all of its leaves over the winter, and, with moderate pruning of damaged branches, keeps right on going in the spring. The peppers are usually very hot, though some varieties have fruit that is milder when it is green. Plants are  shrubs, up to 6 feet tall in milder parts of SF.

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This is what Rocata pepper looks like. It keeps most of its leaves all winter, just needs light pruning in spring.

Peridot peppers are in the species Capsicum baccatum. They grow in the lower elevations of the Andes, where nights are cool, so they can bear a crop in cooler Bay Area sites. And they are a sweet pepper, with only a flash of heat now and then. (See earlier post on Peridot pepper for more photos and details.)

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Peridot Peppers bear in September and October then lose most of their leaves in winter.

I also grew a second variety of C. baccatum last year, which had long fruit, similarly mild, that ripened to orange. I thought it might be Aji Amarillo, the hot pepper often used in ceviche in South America, but apparently not. (Aji Amarillo seems to be a shorter pepper, in addition to being fiery hot.) From looking at web descriptions of C. baccatum varieties, I think I grew Peru Long Orange. The fruit reached 7 inches long, the plant was five feet tall, and it bore very late, into November and December. (It was great to have peppers in winter.)

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This is the one I call Peru Long Orange, before the fruit turns orange.

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Here is how it looks in winter if you leave it on to ripen. Notice the leaves are becoming yellowish.

So now its spring. I left the plants in, to see what would happen. First, a fine, deep green shoot emerged at the base of the Long Orange plant. Then little shoots appeared here and there on that plant as well as on the Peridot. The best, most vigorous, shoots were often lower on the branches, not at their ends. I began a careful pruning program, cutting branches back just above strong shoots. That is, I was letting the plant leaf out first, to guide me as to where to cut. I also worked some aged manure into the soil near the plants (I had turkey manure.) to give them a boost.

By May the Peru Long Orange plant has become quite leafy, lots of big, dark green leaves. It is a foot or two shorter than it was, due to my pruning, but growing nicely. The Peridot shoots are not quite as vigorous (and I don't have a good photo of it yet). Perhaps the fact that Peridot bears fruit earlier in the season is related to its being slightly less able to recover from winter. However, it is too soon to tell whether either plant will bear a good crop this year. I'll let you know.

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Peru Long Orange leafing out in the second year, shown in late April.

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Close-up shot of Peru Long Orange leaves in second year, showing their healthy size and color, and a pruning cut (center)

I must say, however, that plants in a friend's garden are not leafing out as well. The Long Orange in that garden was cut back heavily, before it began to grow new leaves, so perhaps this was an error. The Peridot in that garden was allowed to hold onto much of its ripe fruit through the winter, so perhaps it used up too much energy ripening seeds to have much left for regrowing. (I ate most of my Peridot peppers green, finding the flavor nicer than when it was red, and took off the last fruits in about December.)

I have put in new plants of each, next to the old plants, and will be comparing their performance, to try to decide it is worthwhile to overwinter these plants.

Annie's Annuals anniesannuals.com, grew both kinds of C. baccatum this spring, and even offer Aji Amarillo. If anyone grows any of these plants and has new info to impart, please send a comment.


Controlled Chaos: Welcoming Self-Seeded Plants Into Your Garden

In this month's SF Chronicle column (which will appear December 13, 2015) I reviewed a book called Cultivating Chaos: How to Enrich Landscapes with Self-seeding Plants. Every vegetable gardener knows that some vegetables self-seed in gardens. The mustard or arugula we didn't pull out before they set seed, the last beans, hiding in the foliage until they ripen and drop, the parsnip we let bloom to attract beneficial insects. These all will result in little surprises in the following year. With our long California seasons, with plenty of time for seeds to ripen, we probably see more volunteer crop seedlings than would gardeners in short-summer climates.

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(Self-seeded arugula with Daffodils, in February. A free salad green that decorates the garden until you eat it up.)

               What do we do about it? Depending on our needs, we may let the volunteer grow and eat it. Or, if it is in the way, we may move it, or if that isn't possible, because it will not transplant well, or if we have too many seedlings of it, we pull it out. No problem. We usually kind of like it that nature has given us something we might eat without having to sow the seed. So it is a short leap to enjoying volunteers in our flower gardens.

               The Cultivating Chaosbook is a celebration of ornamental plants that grow from naturally dropped seed, as opposed to seed we replant each year. It will be an inspiration to those who want to have a truly beautiful ornamental garden that embraces some of these plants. It includes many photos of handsome gardens or parts of gardens using self-sowing plants, tips on using them well in gardens, and a plant encyclopedia to illustrate and discuss the merits of a number of plant candidates.

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(I shot this image at Annie's Annuals. This nursery, in Richmond, CA, is a good source of plants that will reseed, such as these red poppies. They are at anniesannuals.com.)

                Here I must acknowledge that some gardeners are afraid of self-seeding plants. It has been a fashion recently to plant home gardens that are like the gardens of a commercial establishment in that the plants have been chosen to grow slowly, need little pruning, and stay put. A thick mulch is applied to keep weeds down, and any wayward seeds usually perish in the mulch. It's called low-maintenance gardening, and I suppose it is, but oh, how I would miss the serendipity of an old-fashioned garden flower bed.

               The authors of Cultivating Chaos understand that one does not want a garden to be 100% chaos. They say the trick to creating a pleasing garden design with self-seeding flowers is to contrast their relative chaos with "clearly defined architectural forms and areas of quiet that are the result of traditional garden planning."

               Yes! I knew this when I decided what I wanted in my own garden. It needed enough structure created by hardscape that some of the planted areas could be more random (or chaotic), with only an occasional formal row of some plant to add a modicum of order. Broken concrete and used bricks create low retaining walls and a patio, with some paths made of concrete pavers or decomposed granite. Now I have to decide how much self-sowing to allow. I have learned, as did the authors of Cultivating Chaos, that much of what goes on to manage the potential chaos is removal of unwanted seedlings.

               Removing self-seeding plants is weeding, really, but what you remove is often, and, as the process continues, more often, a flower rather than a true weed. (If there is bare earth, and even if there is a mulch, really, there will be weeds. So one might as well be weeding out flower seedlilngs as weedy plants with no ornamental value.)

               I must say here that my book, Wildly Successful Plants: Northern California, features a number of self-seeding ornamentals that thrive in our regional microclimates. I grow many of these in my own garden--including columbine, blue nigella Kenilworth ivy, feverfew, linaria, cineraria, nasturtium, Johnny-jump-up, and California poppy. I do buy plants and seed, but I depend on self-sowers to fill in between them and bloom each year without having to be purchased or sown.(And I also have volunteer parsley, chervil, arugula, potatoes, an occasional parsnip.)

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(A self-seeded Alpine strawberry, golden feverfew, purple cineraria, and columbine fill in this corner of my garden.)

               And, as I said earlier, many gardeners are afraid of self-sowers, so they are afraid of my book. A sad fact, since they are losing access to so much useful information, including information on which of the featured plants are deer tolerant, snail tolerant, drought tolerant (most), or attractive to humming birds.

             The book Cultivating Chaos skips lightly over potential problems and over the chance of plants escaping into wildlands. However, in Wildly Successful Plants, I don't skip these hard parts, but have delved into them thoroughly so that a gardener can make decisions that are responsible for our region and for an individual garden.

               One of the main principles of responsibility is that plants act differently in different regions. I was surprised to find lady's mantle (Alchimella mollis) listed in Cultivating Chaos as a self-seeder, as it has never done that in my garden. Nor has blanket flower (Gaillardia). On the other hand, they say that Mexican daisy (Erigeron karvinskianus) can be expected to self-sow only in dry locations with sandy soil. Here, in a dry summer Mediterranean climate, that plant reproduces like crazy (though the variety 'Spindrift', mentioned in Wildly Successful Plants, is said not to produce seed.)

               There is also a question of whether a plant could become a wildland weed. Again, only a paragraph of warning in Cultivating Chaos, but a careful analysis in Wildly Successful Plants. My analysis is possible in part because I am writing about a specific region, whereas Cultivating Chaos, which was written by Germans and which tries to be more universal in coverage, can't deal with the fact that fennel and ox-eye daisy, which they recommend, are nasty weeds here, while lady's mantle, as I mentioned, doesn’t seem to self sow at all.

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(California poppies are featured in both Cultivating Chaos and Wildly Successful Plants, but I've explained in Wildly Successful Plants that the native in the Central California Coast region is this two-toned variety.

               To be a wildland weed, incidentally, a plant needs not only to self-sow, but to be able to compete in regional undisturbed or lightly disturbed wildland habitats. This ability varies by plant and by region, and I've analyzed it carefully before suggesting each plant in Wildly Successful Plants.

               The strength of the book Cultivating Chaos lies not in its analysis of using self-sowing plants responsibly, but in its photos. They give design ideas that will inspire you to want a bit of chaos in your garden. There are all-the-same-color flower plantings and ones with bold contrasting color schemes; informal gardens with only paths through the self-sown beds; and gardens in which chaos plays against formal hedges and hardscape. There are self-sowers peeking up through pavers and ornamenting dry-stone walls. There are photos of plants that have formed handsome seedpods, backlit to show their edges. The photos make me want to create ever more lovely self-seeded chaos in my garden.

Full bibliographic Info:

Cultivating Chaos: How to Enrich Landscapes with Self-Seeding Plants, Jonas Reif, Christian Kress, with photos by Jürgen Becker, Timber Press, 2015.

Wildly Successful Plants Northern California, Pam Peirce, with photos by David Goldberg, Sasquatch Books, 2004.

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(Seedpods of some common self-seeding flowers.)


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.


Master Gardener Spring Sales--Mostly Tomatoes

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Master Gardeners will be holding spring markets in three Bay Area counties in April. As reported in my SF Chronicle Column of April 5, they will be as follows:

San Mateo/San Francisco Master Gardeners will hold two sales. The first is on April 11, 9-1, at Redwood High School, 1968 Old County Road, Redwood City. The second is April 18th, 10-2, at Central Park in San Mateo, and is part of an open house at the park on that day. For more information: 2015 San Mateo/SF Spring Garden Market Information

Marin County Master Gardeners are having two sales on the same day, April 18th, both 9:30-12. One is at the Bon Air Shopping Center, 50 Bon Air Ctr., Greenbrae, the other is at the Pini Market, 1535 S. Novato Blvd, Nave Shopping Center, Novato..For more information: 2015 Marin County Tomato Market Information

Santa Clara Master Gardeners are having their sale on April 11, 9-2 at History San Jose, 1650 Senter Road, San Jose..:For more information: 2015 Santa Clara Spring Market Garden Information

All of the sales include tomato plants galore and Master Gardeners on hand to answer questions and the  April 11th sales in Redwood City and in San Jose include other kinds of seedlings and garden talks, and  a "green elephant" sales.

Each of the Master Gardener Organizations have prepared lists of the tomato varieties they will be selling, with information on the qualities of each variety. Here are links to the three 2015 tomato variety lists:

2015 San Francisco/San Mateo Tomato List

2015 Marin County Tomato Varieties

2015 Santa Clara County Tomato List

 

 

 


Roly-Poly Problems

I got the following question through my web site. I'll answer it below. I was trying to wait until I had a good photo of these little critters, but I don't seem to have very many of them these days, so there's no photo for this post.

The Question:
My veggie garden has been besieged by roly polies.  When I check gardening blogs, most answer that roly polies do not eat live plant tissue but they are definitely eating the base of my cucumber and squash plants. I caught most of them early and taped the base of the stems so they couldn't continue to gnaw away...but they have!!!  They continue to move up the stem even though the stem is tougher than when they were small seedlings.  I have lost a few plants to them. My vegies are mulched with my homemade compost which is a cold one and probably supports the rolly pollies.  How do I rid my soil of them?  They are everywhere!!  BTW I live in San Rafael, Marin County.  Should I solarize the soil?

The answer:Too many garden how-to books and other guides are researched by reading what others have written, so we get the same information over and over. And wrong information over and over is frustrating.

Roly Polies will generally eat any living or dead plant matter that is soft enough, inlcuding much dead, decaying plant matter. If there are only a few of them, they may not damage crops much, but when their populations build up, they do significant damage. While I've never seen sow and pill bugs eat squash stems, I have watched them chew up the blossom ends of summer squash fruit and eat into ripe tomatoes.

"Roly Polies" is a general common name for both sow bugs and pill bugs, which often occur together in gardens. These are two different species of animal, both more closely related to shrimp than to insects. We call the species that can't roll up sow bugs, the ones that form a tight ball when disturbed, pill bugs, but their habits and management are about the same.

Your goal is to make conditions unpleasant for them and to reduce their numbers if they get so numerous that they are becoming pests. Start by pulling the mulch back from your squash plants, leaving a bare area a few inches wide around them. Try to keep this surface, especially, but all of your garden soil or mulch surface, as dry as possible, since these creatures need to stay moist to survive.

I doubt that solarizing the soil will help with sow and pill bugs. They would tend to run out of the hot area under the plastic. You might get eggs, but the adults are very mobile.

Sow and pill bugs tend to congregate in moist dark places in the day time. You have to move fast, but if you know where they are hiding, and see a lot of them in one place, you can scoop them into a plastic bag, seal it, freeze it, and compost them. Or you can leave out traps, in the form of anchored opaque plastic sheeting or cardboard, remove it fast, and start scooping. Try using a kitchen scoop or a deep trowel.

If you have many sow and pill bugs in an area you are about to clear and replant, try to reduce the population before you plant seeds or set out new seedlings there. Waiting a couple of weeks may be enough, but if you have many of the creatures, you may want to use mechanical means, as just described, or chemical means, as follows, to reduce the population.

I never use chemical means as a first resort, but you may want to supplement your cultural and mechanical methods by using a product called SluggoPlus. In addition to the iron phosphate that kills snails and slugs, it contains Spinosad, an extract from a soil microorganism, that is toxic to sow and pill bugs, earwigs, and cutworms. Use it according to directions, including not spreading it any more thickly than the directions indicate, as it is toxic to pets. (If spread according to directions, very thinly, it is less likely that a dog might eat enough of it to harm it, but do read the directions.)

Good luck reducing your roly poly problem!

 

 


Ornamental Ginger--Late Summer Bloom in San Francisco

Ginger IMG_5422 copy
I continue my entries on flowers that bloom in August/September/October in my San Francisco garden. The garden is cool in summer, often foggy, damp, and almost completely in shade in late autumn through late winter. Many common late summer into fall flowers get gray mold or a powdery mildew in these conditions. Here's another that does not.
The plant piectured above was given to me as "ginger". It's Hedychium gardnerianum or Kahiri ginger, a plant native to the Himalayas. (Must be the lower parts of the Himalayas, where winter isn't so cold, but high enough that it doesn't require high heat and can tolerate cool summer nights.) I love having its big, bright, interesting, highly fragrant flowers in my garden at the end of the summer season.

Note that this isn't culinary ginger, not the one that's edible, only an ornamental plant with "ginger" in the common name.

Ginger cl IMG_5424 copy

The part of the garden it's in is in shade, albeit open shade, from August until Aprill. But the plant blooms in late August and into September anyway, and never has a touch of botrytis or other fungus disease.

Here is how the plants look when they aren't blooming. They are 3-4 feet tall.

IMG_6101 copy ginger

In a warmer place, or if they had the right pollinator (not sure which or if it's both)  the flowers would be followed by orange fruits, but they haven't here. I have read that the plant is an invasive weed in Hawaii, where it does form seed, so it's just as well that it doesn't make seed here.

In any case, after they bloom, I cut off the spent flowers. By the next spring, the leafy stems that bloomed start to look kind of ragged, and, if the plant is healthy, about the same number of new shoots begin to come up at their bases. As soon as the new shoots are tall enough to be attractive, I cut the old ones to the ground, or actually, they sort of snap off just at soil level.

For the first 2-3 years I had the plants, they didn't bloom and made few new shoots. Whether they were just young, or needed better care, I can't say. After that time, I started fertilizing the plants in spring and summer, and giving them more water, and then they started blooming and growing new blooming stems each year.

Next entry (to come soon): California fuchsia vs. pineapple sage--two hummingbird pleasers.

 


More on Early Blight of Potatoes & Tomatoes

(See photos in the previous post)

In my last post, I reported having seen some potato plants in San Francisco with what looked like early blight, a disease caused by the fungus Alternaria solani. I remembered from my research for the book Controlling Vegetable Pests, which I wrote in the early '90s, that this disease is not common here in California, but much more so elsewhere in the US. I wrote then that it is "less common in arid regions of the West, although overhead irrigation and frequent heavy dew promote disease in these areas." It showed up the week after we had an unusual June rain, and in a garden that has frequent fog. But the question is: Where did the spores come from?

My first thought was that someone had planted potatoes from the grocery store. These could carry the spores, even without symptoms, or could have had dark lesions with underlying brown or blacky corky rot from spores that grew on their surfaces. However, the gardener assured me that these were purchased at a nursery as certified disease-free.

So the spores must have blown in from a nearby garden or were carried in the rain. Then they landed on potato leaves that had some injury, at a time when the temperature and amount of hunidity were right for them to start growing, and the rest is history. The ideal temperature for early blight spore growth is 75-80 degrees F, but the symptoms develop fastest at 70 degrees. 

This disease can also infect tomato, and, occasionally, eggplant or pepper. Wild relatives of these plants are also susceptible. On tomato, the leafe symptoms, the bull's eye spots, are the same as on potato, and there may be sunken lesions on older stems. In additon, there may be excessive blossom drop (common here anyway due to cold nights) and leathery, sunken, dark brown lesions on the stem end of the fruits.

If this disease shows up in your garden, take the plants out of the garden. (In San Francisco, they can go in the Green Bin, since the municipal composting system will heat up enough to kill the spores.) If potato plants have formed tubers, eat them up soon, as they may decay in storage. Don't store them where you will kep other, healthy, potatoes later.

The spores can germinate in plant material from infected plants as long as it has not completely decayed, so pick up every bit of the plant and dig up most of its root. Do not save seeds from tomatoes that ripened on infected plants, as the spores can hide in the seeds.

Remove any solanum weeds that are growing in your garden, as they can harbor the disease. (They have flowers similar to those of tomato, but usually with white or pale lavender petals, and have clusters of small, inedible berries that turn black when ripe.)

Plan not to grow tomatoes or potatoes in the place where infected plants grew for two to three years.

When you do plant potatoes or tomatoes, provide your plants with adequate water and fertilizer and avoid getting water on the leaves of tomato'potato family plants. Start examining them when they are about a foot tall to be sure they do not have symptoms. Prevention is more successful than cure when it comes to plant diseases, but if you have had the disease, or if you see the first lesions it is causing, you might try the fungicide Serenade, which is based on a soil bacterium. Follow directions on the label, including repeated sprayings as it directs. (If you are spraying after seeing lesions on a leaf or two, pick off those first infected leaves before you spray.)

May early blight of tomato or potato not darken your door, or the leaves of any plants you are growing to produce food!