DryStoneGarden

Aspens with California Poppy

Aspens in the Bay Area? Somewhat in keeping with snow on Mt. Diablo, not really the popular image of our area, but there they are. According to Sunset, P. tremuloides ‘generally performs poorly or grows slowly in lowlands; usually short lived in warmer climates.” The ones at the Tilden botanic garden seem to be doing well, though it’s true they aren’t large and did probably grow slowly. They were definitely one of the most beautiful things in the garden when I stopped off on my way home the other day. We get asked about aspens sometimes and have always advised people to plant birches instead, but clearly aspens can work, so maybe we need to modify that advice. The bot garden is in a cool micro-climate (small valley surrounded by hills) and there was ice on the lawn and on a few of the plants, so that might be helping these aspens. Next year I need to remember to stop off and see their fall color. This has been a good year for fall color in the Bay Area, so they were probably beautiful.

Redtwig Dogwoods with Aspens

Sunset also says aspens make a ‘good background tree for native shrubs and wildflowers.’ Indeed. I like how the redtwig dogwood and the aspens are both somewhat see-through, and how the colors are so strongly contrasting even as the upright forms are so similar. We’ve planted redtwigs against a light-colored wall a few times, and last week we planted a yellowtwig dogwood against a brick chimney. The line of aspens is just as architectural and works just as well for a backdrop.

Redtwig Dogwoods and Aspens

Specimen Manzanita with Manzanita Backdrop

One of my reasons for stopping at Tilden was to look at native plants in the winter and see what was blooming in December (Answer: not much, a few late blooms amongst the deadheads on some buckwheat and erigeron species, two raggedy grindelias still blooming, a few stray off-season blooms, and about one fifth or one quarter of the manzanita species.). We talk to a lot of people who think natives only look good for about half of the year and sometimes I find myself believing that a bit, too, so it was good to walk around and see which plantings looked good and which ones would look ratty to that percentage of the population out there who are skeptical of natives. A lot of the garden and a lot of the plants were looking really beautiful, even though it was a gray day right after a cold storm. The rainforest section was looking great (though it was too dark under the canopy to take photos) but I don’t think there’s much debate about how great the woodland natives can look. Probably the biggest problem for northern California natives is just that many people don’t think of them as California natives, instead mentally classifying them as Washington/Oregon natives.

California Fuchsia Planting

I think that when many people say they don’t like natives, they have a mental image of California fuchsia in winter, and when other people say they love natives, they have an image of Cal fuchsia in summer. This is a successful planting to my eyes, but this look seems like an example of what makes some people hostile to natives, a wild-looking plant in a rather wild-looking planting. It also seems to reflect the established popular image of a ‘native planting,’ even though natives can be used in so many other ways and to create so many different looks. I’ll try to return and take a photo from this same spot when the Cal fuchsias are blooming, because they are really pretty in bloom.

Coastal Bluff Planting

The buckwheats, another species not known to shine in the winter, looked good in some plantings and not so good in others. The Coastal Bluff section has a strong design, so the prominent buckwheat in the planting also looked fine and the planting would still look fine even if the buckwheat were replaced with a dying-back Cal fuchsia.

Cold Frame at Tilden

Hello Dudleya

The desert section had some cold-frames out in the southern California desert sections. There’s no question about Agave shawii looking good in the winter. They’re really a Baja native that had a few populations on our side of the border, but those populations have been displaced and now might only exist as revegetation plantings. San Marcos Growers says they’re growing it, so it might start showing up in nurseries more often. Apparently, it’s really slow from seed.

Agave shawii

Agave shawii

Ninebark Thicket

The ninebark thicket (Physocarpus capitatus) reminds me of a crustacean, either a limpet or maybe a barnacle. I doubt this is going to inspire many people to plant ninebarks or shear them into a limpet shape, but it’s actually being used pretty well here, an effective way to make a certain type of habitat plant look intentional and not too wild. And I bet the birds love it. It looks better than the Salvia leucophylla, which is generally considered more garden worthy but was looking just as deciduous and thickety as the ninebark. In fairness, the S. leucophylla is planted in a tough spot, up against a bridge on a steep slope leading down into a creek.

Salvia leucophylla, Purple Sage

Sugarbush, Rhus ovata

I just planted Rhus ovata (Sugarbush, an evergreen sumac) for the first time, three of them at my parents’ house. The Watershed Nursery has had a supply recently, one of the first times I’ve seen them available. ( — edit — my bad, I realized that I planted the other evergreen sumac, Rhus integrifolia.) Hopefully the ones I planted will look as good as they do here. I like the flower buds as much as I like their little white flowers. This one here looks ready to do a huge bloom in February or March, that time of year when even the native skeptics agree that California natives look beautiful.

Sugarbush, Rhus ovata

Update — And here is a March photo of that ninebark thicket in leaf. Still not the most ornamental plant in the garden, but not too bad.

‘So if the bird flies away, or if you’ve identified it, you can turn your attention to the tree in the same view, without moving your binoculars or telescope, and have a whole new challenge of something to identify.’ Sibley

Sibley came out with a tree guide! I haven’t yet seen any mention in the garden world, but the birding blogs are on it. 10,000 Birds has a review and an interview, and there’s a 3-part interview with him in Birder’s Magazine. He put together the guide as a birder rather than as a botanist, writing with birders as his target audience, and it’s interesting to see the elements of his bird book carry over into a tree guide.

The most obvious carry over is the life list at the back of the book. I don’t think I’ve ever met anyone who keeps a life list for trees, though the idea is intriguing. Bristlecone Pines were certainly something I felt I needed to see, and the east coast members of my trail crew this summer arrived out here determined to see a Giant Sequoia before they headed home, so the idea does make some sense. It might be interesting to keep track of how many different trees I can see just in the Bay Area.

Instead of photographs, the book uses paintings, which work better for birds and seem to work better for trees, too. The guide includes native and non-native species, making it more useful to me than, for instance, my Audobon guide which only includes native species. I find I already know a lot of the California species, but that it’s the tall non-native shade trees, trees I rarely plant or buy at the nursery but sometimes find in clients’ yards, that I need help identifying. I tried out the book with a couple of trees, the English Walnut in our yard and the Red Oaks where I was working today, and it seemed easy to use.

And it was nice that I went through the ID process without a key. Keys went out of style in the birding world a long time ago, and I’ve never liked using them for trees; they seem like a relic from old-fashioned, rote-style learning. In the Birder’s magazine interview, Sibley says he wants readers to engage more directly with the book.

‘I really wanted the book to work the same way the bird guide does. That is, if you see something interesting, whether it’s a leaf or some odd bark or an unusual type of fruit, you can open up the book and just start flipping through the pages and try to find a picture that matches.

‘I think in the long run, that’s actually more helpful and more educational than working through a key, because after you’ve done that a few times — flipped through the pages of the book, looking for things that match — you’ll realize that if you’ve seen an odd fruit and it’s not an acorn, you can skip the whole 40 pages of oaks in the middle of the book. You start to get a sense of what the variation is in all the types of fruit. Pretty soon you’ll be out in the field somewhere and say, “There’s an odd fruit. I don’t know what that tree is, but I know I’ve seen that picture in the book, and I think I remember it being toward the end of the book,” and flip through the pages and find it and put a name to it.

‘By flipping through the pages and getting an overall sense of what’s out there, you subconsciously begin to understand larger patterns — which families are similar, which families are different, what makes all the oaks similar to all the other oaks, what makes willows and poplars so similar that they’re put in the same family. You’ll develop an understanding of that simply by flipping through the pages of the book.’

I know I became a more knowledgeable birder when I discovered Sibley’s bird book. It’ll be interesting to see what I learn from his tree book.

— Addendum —

I have noticed signs that the guide was written by someone from the east coast. For instance, the guide does not include ceanothus or manzanitas, an omission in my opinion. Sibley’s definition of a tree is ‘anything that you can walk under,’ and manzanitas and ceanothus definitely meet that standard, though I suppose the 30 foot tall manzanitas and treelike ceanothus are known primarily within California native plant circles. And at the same time as the guide excludes manzanita and ceanothus, the guide includes the less treelike Toyon and the less common or iconic Western and Utah Serviceberries and the Mountain Mahogany, probably because there are large old specimens in some of the arboretums back east and in England. I say this not so much a complaint, but rather as an observation, something to maybe fix in future editions; the book is a national guide with a national perspective. And as I was saying, I already have plenty of books for the native trees. Interesting, though, that I find it most helpful for identifying the east coast and european specimens that I find in California gardens.

Manzanar Cemetery Monument

I’ve been meaning to post about this for a while, but I wanted to first reread Farewell to Manzanar, Jeane Wakatsuki Houston’s memoir of her childhood in the internment camp. I hadn’t really thought about that book since reading it back in eighth grade, but while I was out on the east side I visited Manzanar, an interesting place to visit despite the fact that there’s not a lot there any more. Whether for practical or more guilt-oriented reasons, the site was almost completely erased after it closed in 1945. All of the buildings were dismantled and hauled away, leaving only some concrete foundations, the large auditorium, two stone sentry posts built by a stonemason internee Ryozo Kado, the cemetery with its concrete monument (also built by Kado), and the remains of a few gardens built by the internees. Now, the place feels barren and desolate, which is, I guess, appropriate.

The park service has done a lot of work to put together a visitor center that gives a sense of what life might have been like in the camp. Their website says they will have a virtual tour online in the future, but for now the wikipedia page or this article in Lost Magazine have the most info and links that I could find on the web. Farewell to Manzanar, though, is the best source. I don’t remember the book making much of an impression when I was young, but this time I found it quite compelling, perhaps because the story is relevant to our country’s recent history.

Entry Pillar

Kado’s work is all very meticulous for someone who was essentially a prisoner. He created almost everything that remains at the site, which may I guess have been a motivation. There’s a saying: If you want it to last, build it with stone. His stonework makes this memorial possible.

Military Police Sentry Post at Manzanar

The lintels are made of concrete finished to look like wood, apparently a signature of Kado’s work.

Concrete with Faux-Wood Finish

The posts at the sentry station resemble a tree trunk, while the ones in the cemetery have a smooth finish as if they were scoured by sand or water.

Manzanar Cemetery Monument with Posts

Manzanar Block 34 Garden

There are the remnants of several traditional Japanese gardens built by the internees. I don’t know of any photos that show the gardens in their prime, but they look like they were quite complex, involving water features, landscape boulders, and masonry. Kado was one of the main creators, and some of the concrete ponds were lined with more of his faux-wood masonry. This article talks about the park service’s archeological efforts with the gardens, including more details about Kado and a number of photos of the garden ruins. In person, the effect is quite powerful, especially for someone like myself who creates gardens for a living.

Garden at Manzanar

Houston talks about the gardens in her chapter about revisiting the ruins of Manzanar.

‘It is so characteristically Japanese, the way lives were made more tolerable by gathering loose desert stones and forming with them something enduringly human. These rock gardens had outlived the barracks and the towers and would surely outlive the asphalt road and rusted pipes and shattered slabs of concrete. Each stone was a mouth, speaking for a family, for some man who had beautified his doorstep.’

Photos #5 and #6 from Wiki user Mav.

Update — 99% Invisible has a podcast telling the story of the establishment of Manzanar National Historic Site, as well as some great photos by Ansel Adams and Dorthea Lange and creator of the podcast. It looks like the park service has done a lot of work developing the historic site in the eight or so years since I was there.

I recently netflixed Standing with Stones, a travelogue overview of the megaliths, henges, and stone circles of Great Britain. It’s good stuff, put together by just two guys, the filmmaker and the narrator. My favorite parts were probably the segment on Men-an-Tol and a short rant about some misguided preservationists who “restored” Newgrange using Portland cement. There is maybe a bit much of “…and we have no idea what it was for!” but I suppose that’s a reflection of how ancient these stone sites are and not really the fault of the filmmakers. Personally, I had no idea there were so many sites and that they were so old. Those early Brits really liked to move rocks.

A playlist with 15 segments can be found on Youtube. The filmmakers have an interview up on Youtube and an interesting blog.

Failed Moss Rock Wall

In light of all today’s talk about tearing down that (Berlin) wall, here’s some photos of the biggest wall to come down in my neighborhood this past winter, when a section of hillside pushed a moss rock retaining wall into the road. Must have been a shock to the homeowner and whoever built it (not me).

Though, without sounding like I’m piling on the unfortunate builder of the wall, it was predictable that this wall would fail. A three foot high wall is supposed to be two feet thick at the base, and this wall isn’t even one foot thick. It also doesn’t have a proper foundation or gravel backfill. I see a lot of failed retaining walls around town, and the common denominator is that they are always backfilled with dirt instead of the drain rock or rubble that virtually every book or manual recommends.

Failed Moss Rock Wall

Intact Section of Wall

The wall is still intact where the bottom course has bigger rocks and the rocks are toed in against the curb.

Failing Section of Wall

Failing Section of Wall

Moss Rock

Two more waller nightmares are below. Read the rest of this entry »

Pack Mules on Duck Pass Trail

The topic for this month’s design workshop at Gardening Gone Wild is dealing with slopes. The description mentions “tips for building steps and paths to make slopes easier to navigate,” so I thought I’d cite the source I learned from, the forest service Trail Construction and Maintenance Notebook, which is online and in the public domain (Who owns this government document? We do!). The text might have a few elements geared towards public trails rather than residential gardens, but the diagrams are good and the principles are solid.

Step Construction

‘Build stairways from the bottom up, at a break in the grade. The most common mistake is to start part way up a grade. If you do so, the trail will wash out below the stairs. The bottom stair should be constructed on a solid, excavated footing. If it is constructed on top of exposed rock, it should be well pinned to the footing. Each successive stair is placed atop [or against] the previous stair. Dry masonry rock stairs usually rely on the contact with the stair below and with the footing to provide stability.

‘Hikers, especially backpackers, generally don’t like steps and will walk alongside them if there is any opportunity. The steps need to be comfortable to climb or they won’t be used. This means keeping the rise a reasonable 6 to 8 in (150 to 200 mm) and the run long enough to hold a hiker’s entire foot rather than just their toe. It’s helpful to armor the sides of steps with rocks to encourage users to stay on the steps.’

Stepping Rock and Riser Stairways

‘The most important area of the step is usually in the run. This is where most traffic steps as it climbs. If the step is composed of something like a board on edge with fill behind it, then the traffic will step onto the landing. Almost all foot traffic descending the step will walk off the edge of the step. The top of the step (and landing) should be stable and provide secure footing. The edge of the step should be solid and durable. The face of each step should not contain a batter that creates a “face run” of over 2 in (50 mm) from top to bottom. This is particularly important as the rise of the step increases.

‘Steps with landings are a bit harder to secure in place because the stairs do not overlap. Each step can either be placed in an excavated footing and the material below the rise removed to form the landing of the next lower step. This is usually the most stable arrangement. Or the step can be secured on the surface and fill used to form a landing behind it. The material used to provide the rise does double duty as a retaining structure when the landing consists of tamped fill. These steps must be seated well to prevent them from being dislodged by traffic. For stock use, landings should be long enough to hold all four of the animal’s feet.’

Riprap Stairway

‘In more primitive settings, you don’t need a uniform flight of steps as long as the route is obvious and there is solid tread at each stepping point. In the Sierra, a cross between cobblestones and stairs, locally called riprap, is commonly used for this purpose.

‘If the stairway climbs straight up the hill, each step should be slightly crowned to drain water to the edges or slightly sloped to one side. When the trail traverses a slope, each step and landing should be slightly outsloped. Water should not be allowed to descend long lengths of a set of steps or to collect on or behind a step on the landing. A drain dip where the trail approaches the top of the steps is a good idea.

‘In all steps, the key is to use the largest material possible and to seat it as deeply as possible. Rocks should be massive and rectangular. On steps that traverse a slope, it helps to seat the upper end of the step material in footings excavated into the slope.’

Rock Staircase

Best practice for building a stairway these days, if the rocks are big enough, is to butt them against each other instead of on top of each other. That way it is possible to repair one of the steps without redoing the whole staircase.

Rock Staircase

It doesn’t say in the notebook, but I was taught to kick test every step. If the stone moves when you kick it, it isn’t solid enough. A bit of a shock, sometimes, to see someone kick the structure you just labored on, but the step is definitely going to get kicked when people use it, so you might as well find out if it is going to last. You want to feel confident that your stairs are safe. It’s scary enough the first time you see a mule train crank through a set of steps that you’ve built even when you know the steps are solid. There aren’t mules in residential backyards, but the foot of a 150 lb. person can easily impact with 300 lbs. of force, so the basic principle is the same. Steps should be strong.

Steps also need to be regular. The test is to walk up and down the stairway without looking down at your feet. If the rise and run are even, you shouldn’t trip or stumble.

Old Town Wall Steps

In the front country I usually don’t get to work with stones that are “massive and rectangular,” but I still kick test every step and walk the staircase with my eyes closed. This set of steps, built with a local sandstone called Old Town Wall, was a lot of work, getting the risers to all match and the stones all interlocked enough to stay in place. I was working for a designer who is a serious dry stone purist, so mortar was out of the question. I think the steps and cheekwall took me longer than the entire rest of the wall.

Mortared Arizona Flagstone Steps

When it’s up to me — though I’m a dry stacker at heart — I usually build steps with mortar, usually by stacking flagstone with a recessed mortar joint. I don’t think that method holds up in areas with heavy freezes and probably not if the steps are going to be used by mules, but it does well in Bay Area gardens. A before photo of these steps and another mule photo are below. Read the rest of this entry »