Monthly Archives: February 2010

gardening, landscape, my garden

after the rain delay

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The rain last weekend cleared out long enough for us to install the shade panel we’d constructed.

The fence you see faces north by northwest. Anything growing in the bed is in total shade for several months. About this time of year, though, the sun swings north, and things start to get sun exposure in the later parts of the day. We removed the termite-munched patio cover that shaded the delicate plants last fall–it had to go–but suddenly time was of the essence in restoring shade.

This is where a few shade denizens live in the bed…

…along with John’s collection of orchid cactus, Epiphyllum, that he’s amassed over the years. We also have a small assortment of hanging tillandsias and some tropicals, including a few surviving orchids from my rabid orchid-growing days two decades ago.

This weekend has turned rainy again, filling many of the holes in the shade screen with water. It’s slowed down moving the plants to their new home, but I won’t complain about the water we’re getting.

We’re already two inches ahead of the entire rainfall for last season (July 1, 2008 to June 30, 2009). And last month’s rain accumulation alone, 5.4 inches, came close to the 5.5 total for all of 2009. Still we have a couple inches to go before we can even claim an average rainfall year.

This season’s rain is filling up vernal pools after several years of disappointments. Friday I stopped by some pools with a biologist to scope out a potential field trip for the local native plant society. Vernal pools are among the most threatened habitats locally. The occur on our mesa tops, areas that prove irresistible to developers because they’re flat and require less soil preparation than canyon bottoms or slopes.

Young plants were everywhere, including those of San Diego mesa mint (Pogogyne abramsii), a plant on several endangered species lists. If the rains keep up, it looks like it’s going to be a great year for them.

gardening, my garden

rain delay

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It’s almost never too rainy to garden, and of course it’s never too wet to blog. But some outdoor projects have had to be put on hold temporarily.

Yesterday, when it was still dry, we started to construct a shade panel to begin to replace a patio cover we tore down last fall. Many of the plants on the patio are shade plants, and we still have some shade plants hanging in the shade of the greenhouse. As the weather warms and the sun begins to burn hotter in the sky many of the plants are starting to need some cover.

We got this far on the panel project yesterday. It’s a ten-by-four foot frame of aluminum, with an inset of perforated aluminum mesh. The diagonal cross pieces are for both structural support and what I hope will be a level of coolness.

And then it began to rain: Light mist now and then yesterday, and occasional rainsqualls this morning. Not safe weather for operating electric devices outside, but nothing to stop me from pulling some weeds and then stopping by my favorite local nursery, Walter Andersen Nursery. There was a bald spot out front and I needed a plant to fill it. One plant.

But the nursery was oozing green life force that proved irresistible and I came home with three instead: white flowering currant (Ribes indecorum), Route 66 California fuchsia (Zauschneria california ‘Route 66’) a second plant of Ceanothus ‘Tuxedo’ to go with one I purchased last year. I’ve resolved to plant at least fifty per-cent California native plants, and I think I succeeded. The first two qualify, and the last gets partial credit. (I have a post in the works describing why.)

Of course for me rainy days turn into opportunities to collect more rainwater for the prima donna bog plants that detest the water that comes from the tap. At this point I probably have several months’ supply in buckets and barrels. And the ground will hold its moisture and require minimal watering for several weeks. I wouldn’t want to force our county’s golf courses go without water, would I? (Well, yes, actually, I would. Yet another blog post…)

gardening, my garden

from leaf to mulch

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For my first attempt at participating in Pam at Digging’s Foliage Follow-up Day I looked under the grapefruit tree for inspiration. As the leaves fall from the tree they go from green to brown to gray before they finally become part of the compost that enriches the top of the soil. That last stage produces some gorgeous artifacts, where what’s left is mostly the thicker veins of the leaf. Even as the leaf tissue between the veins becomes compost or is consumed by the little critters living in the mulch, the structure of the leaf still remains.

Here’s a series of photos of those last recognizable traces of formerly-living leaves. Most of the below take advantage of the fact that the shadow can seem much more substantial as the thing itself. Maybe it’s a metaphor for the lasting power of a leaf that is about to become compost? Something about the cycle of life?

gardening, my garden

plants as compass (february bloom day)

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I was looking at my blooming Agave attenuata and noticed something for the first time. The flowers on its spike have been opening asymmetrically, with the south-facing buds opening a few days earlier than the ones on the shaded side. I guess it’s the agave equivalent of moss growing on the shaded north side of a tree trunk. As I looked at all the agaves in the neighborhood, I was noticing the same thing: All the south-facing buds open first. It makes sense, I guess, with the sun-warmed buds developing sooner than the ones growing in the shade. There must be a botanical term for this–I’ll see if I can’t look it up sometime.

Something else I noticed the other week was that two of the little rosettes growing underneath the growth producing the big spike are also blooming. They’re nice, but the blooms get pretty lost in the foliage.

And compared to the big main spike, which must be something like twelve or more feet from base to tip, you can see how it’d be easy to overlook the little pups…

In the photo above you can make out this big red aloe in the background, Aloe arborescens. The clump began as a one-gallon plant in the early nineties. Now it’s probably six feet tall and twelve across.

February in Southern California is a busy month for flowering plants. Here’s a selection of what else is blooming in the garden.

This raised planter of Oxalis purpurea is the first part of the garden that visitors encounter as they head up the front steps. Dozens of white flowers and a lone pink one in the front. Oops.

Verbena lilacina, greened up from the rains, beginning to hit its stride.

One of several plants of Nuttall's milkvetch, Astragalus nuttallii, that I raised from seed last summer.

Snapdragon-relative Galvezia speciosa 'Firecracker,' never a prolific bloomer for me, though mine's a young plant.

The pink-flowered, purple-leaved form of Oxalis purpurea.

Carpenteria californica, a California plant that reminds me a lot of sasanqua camellias in its simple contrast of stamens against broad petals.

First flowers on Phlomis monocephala.

February flowers on a yellow crassula that I've forgotten the name of...

The final blooms of the season on another crassula, your basic jade plant, Crassula ovata...

The fragrant Solanum parishii, a widespread California native, doing battle on the slope garden against iceplant, Algerian ivy and Bermuda buttercup.

Freeway daisies (Osteospermun) below, with black sage (Salvia mellifera, prostrate form) above.

Keeping up the daisy theme, Arctotis acaulis hybrid...

Another actotis, 'Big Magneta'...

...and a final photo, a final arctotis, shown against a piece of garden art made from glass, steel, and concrete.

As always, my thanks to Carol at May Dreams Gardens for hosting Garden Bloggers’ Bloom Day. Even with snow on the ground many places up north, there’s still plenty in bloom today in warmer, more southern locations, and on windowsills and greenhouses around the world. Check them out [ here ].

gardening, my garden

plants falling asleep

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White Oxalis purpurea closing up for the evening
White Oxalis purpurea closing up for the evening.
Detail of white Oxalis purpurea thinking about some shut-eye.
Purple-leaved Oxalis purpurea closing up in the late afternoon shade.

A lot of the flowering plants in the garden don’t bother opening their petals until the sun’s up and then shut their flowers as soon as the light begins to fade and temperatures drop in the afternoon. Over the weekend I was noticing this going on with my oxalis plants and, less dramatically, with my arctotis.

There must be a name for this behavior, I thought, and so off I went looking for an answer. Before long up pop three interesting words: photonasty, thermonasty and nyctinasty.

According to one of the sources, the Textbook of Botany by Chhatwal and Singh, photonasty happens when a plant senses light and reacts to it by opening or closing its flowers. Because of this, morning glories open in the…well, morning. Then there’s thermonasty, where flowers react primarily to temperature. Tulips will open with a rise of 2-3 degrees Celsius, while a crocus will zip open when the temperature rises just a half degree.

And then there’s the more complex phenomenon of nyctinasty, which “is influenced by the intensity of light and also temperature differentials, the former stimulus being more powerful and effective. The foliage leaves and also the floral leaves in many species of plants…attain different positions at day time and at night viz during the day, the leaflets remain open or spread up in case of Oxalis, clever beans, alfalfa, etc., while by the onset of darkness they close down. This is also known as sleep movement.”

Yesterday afternoon was pretty bright, but cool. The oxalis barely opened before shutting back up. So it requires both heat and warmth to open fully. So nyctinasty makes sense. The arctotis seemed to open more fully, earlier in the day. My guess is that they respond more simply, mainly to light, which would mean that they exhibit photonasty. (What’s truly going on could be lots more complex than this and really might only be solved by experimentation, a point made in an article, “Flower opening and closure: a review” by Wouter G. van Doorn and Uulke van Meeteren in the Journal of Experimental Botany. Read the interesting text [ here ].)

Next I need to find out what “clever beans” are.

In my web trawl it turns out I’m not the only garden blogger looking at this phenomenon this week. Tilthy Rich took a quick spin around nyctinasty [ here ]. Maybe he has the same plants blooming, making him ask the same questions…

Flowers of Arctotis acaulis 'Big Magenta' beginning to fold up for the night.

Another clone of Artotis acaulis closing up in the afternoon: Photonasty? Thermonasty? Nyctinasty?

gardening, landscape

our gardens after we’re gone

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Ever wonder what your garden would look like if the human caretakers just vanished?

Maybe I’ve been inspired by all the disaster flicks like 2012 or the History Channel’s Life After People series. But envisioning gardens after gardeners is an interesting intellectual exercise that might help us answer that pesky question: What is a garden?

Would all the invasive species take over? Would the native plants reclaim their turf? For how long would you still be able to tell that a garden existed in a spot in the first place?

I looked at parts of my back yard and tried to imagine what would happen.

Within the first month, in Southern California’s dry climate, most of the potted plants would perish for lack of water. Some of the succulents might hang on longer, but without an extensive root system in the ground, they’d be doomed.

This little frog would be staring at a bog garden where all the bog plants have died back, once again for lack of water.

Within two or three months the fishponds would be dry: no waterlilies, no cattails, no sedges, no water for the local birds.

This pathetic patch of grass would go through boom and bust cycles, turning green with the rains, dying back to brown other times of year. Seeds of other plants better adapted to the conditions would eventually take hold. Maybe some plants from the local canyon. Maybe some hardy exotic or invasive species.

Behind the back fence of the house is this slope dominated by rampant iceplant. The the neighbor behind me and I haven’t been able agree on what to do with the space. I’ve planted a small collection of native plants to help stabilize the slope. These are species that with only once exception can be found within a five mile radius of the house, and include plants like this nightshade, Solanum parishii…

…and Del Mar Manzanita, Arctostaphylos glandulosa ssp. crassifolia, an extremely rare plant that’s on the Federal endangered species list. The neighbor, however, loves their iceplant and can’t imagine of a slope without this gawdawful invasive species clamoring all over it. The local chapter of the California Native Plant Society has prepared a great pamphlet on getting rid of iceplant that you can view [ here ]. It goes into some great reasons to get rid of the stuff:

Planted on hillsides of thousands of homes in San Diego, it has since crawled off the original site and into neighboring Open Space parks, endangering unique plants by smothering them. Iceplant provides little habitat value compared to the plant community that it is replacing. Compared to the native shrubs, iceplant has very shallow roots that do not hold soil well; close inspection often reveals gullies underneath the twisted mat of vines. After rain, Iceplant engorges with water, substantially increasing its weight. As a result, iceplant can cause the deterioration of steep hillsides by encouraging slumping – potentially endangering the house above.

For people in suburbia, “habitat value” might mean plants that harbor scary wild animals and bugs, so that’s not always the most compelling reason to go native. The fact that iceplant might endanger their property values could be more persuasive.

So, returning to my main topic, the iceplant would probably overrun most of the native plants in a very few years and form a deep pile. Once we neglected the slope for a few years and found that the mat of iceplant was starting to push the back fence over. Within ten years the fence would begin to fail and the iceplant would begin its descent into the lower garden.

These plants along the back fence would stand a chance of surviving without water. The yucca, palm, protea would be tall enough to survive an onslaught of marauding iceplant from behind. They’re plants that don’t require much maintenance, and this wall of foliage would probably look unchanged for a number of years. But the lower aloes and other succulents would likely be smothered by the iceplant.

This apricot against the back fence never looks great without summer watering, but it survives. It’s tall enough that it would probably survive the iceplant invasion. Some of the adjacent native plants do great with the natural conditions. They might not cope so well with the marauding iceplant.

The neighbor on the side has Algerian ivy that requires constant clipping to keep it next door. Within two years it would begin to establish itself in the back yard. Taller plants that might survive the iceplant invasion might have ivy crawling up and smothering them.

This raised bed near the house is where veggies and irrigated plants live. Most of the exotic plants wouldn’t make it without water. The Dr. Hurd manzanita, the bougainvillea vine and maybe the Garrya elliptica would probably hang in there, however, maybe for decades, maybe for much longer.

Fifty to seventy-five years out the house would start to fail. Plants might begin to move in. The surrounding garden space would be overgrown with the hardiest drought-adapted species. I almost never plant in rows, but the mixed origins of the species–South Africa, South America, Europe, as well as from all over California, not just local species–would clue an investigator into the fact that a garden existed on the site. The relationships between the plants would be dictated by nature, not a gardener preserving order between plants with mismatched levels of vigor.

Chances are excellent that one hundred years out, maybe two hundred or more, the most persistent invasive species would still be here. Iceplant and ivy, plus fennel and black mustard that have invaded the local canyons, would feature in the neighborhood landscape. But while many invasives bask in the newly disturbed earth of a garden or the re-engineered grades around roads, they don’t always do so well long-term. Biologists have suggested that many native plants would return to a place where they’re not being pulled out or constantly mowed. My yard might be colonized by the local Mexican elderberry, or toyon, or lemonade berry, or prickly pear. And maybe some of the plants I’ve already introduced to the yard will persist and reproduce. The restoration of nature might spread from my house and from the wild edges of nature just a few houses away.

Even after nature returns, the occasional hardy exotic plant surviving amidst the natives, along with some of the neighborhood’s plantings of trees and shrubs in rows will make it obvious: There used to be gardens here.