Recommendation: SF’s new Crosstown Trail

By Lauren Lewis

Hidden Garden StepsWe’ve entered the rainy season (phew!), which means fulfilling our need for outdoor time will take a little extra effort. If you’re feeling a bit ambitious, one fun way to be outside in the city would be to walk the Crosstown Trail, a new continuous walking route that runs diagonally across SF from Candlestick Park to Lands End. The trail and its originators were recently profiled in the New York Times, and while the author holds a pessimistic view of SF in its current form, the trail itself and the ideas behind its creation are full of optimism. So whether you choose a free day and hike it end-to-end or you cover the trail in small stretches (maybe a fun 2020 goal!), you’re likely to see some of SF you haven’t seen before and you’re certain to get some beneficial nature time.

Update: I did this hike end-to-end on January 5th and it was truly epic. My legs were sore for a good chunk of the next week, but now when I drive by all the various places I walked I have such good memories and pride in myself and our city.

Why you should be a spider for Halloween

By Lauren Lewis

In honor of Halloween season, we thought we’d highlight the super important and “scary” garden resident: the spider. Most people are very familiar with the idea of beneficial insects, who control the population of unwanted insect pests by eating them, but we normally think of a cute ladybug eating aphids off roses. Studies have shown that in fact spiders are often the most important category of arthropods for maintaining healthy species balance in a garden.

Wolf spiders (a category with many species) are important in SF gardens because theyWolf spider carrying babies are aggressive ground-dwelling hunters as opposed to web builders, so as a group, they’re eating more insects. They love mulch in the garden because they can hide among the tiny spaces it creates, so spider protection is just one of the many reasons we use a lot of mulch in our gardens.

Our design outlook is about appreciating and supporting all the living and nonliving elements that make a piece of nature function, and spiders have an under-appreciated but vital part to play.

Nerding out on: Roots

By Lauren Lewis

When you look at the plants in your garden you’re actually only seeing half of the garden’s total mass; in most species a full HALF of the plant mass exists underground in the roots. Deep, healthy root systems offer so many benefits to the plant and its surroundings. One of those benefits is soil carbon sequestration, whereby atmospheric carbon is brought deep into the soil for long term storage by (1) photosynthesis in the leaves followed by (2) movement of the resulting sugars to the roots. In our gardens we favor perennial plants over annuals for tons of reasons, but one is that perennials’ deeper root systems do much more to lock carbon away in the soil.

Another reason is that long-lived roots and the environment they create allow for plant communication. Trees can actually use their huge root systems to support and communicate with their neighbors, somewhat compensating for their inability to move or vocalize. Tree roots are colonized by mycorrhizal fungi, which create a physical connection between distinct trees via the fungi’s intricate web structure. Molecules can make their way out from a tree’s roots, through the fungal network, and into another tree’s roots, sending chemical assistance or signals or both. We highly recommend this lovely video lesson if you want to learn more about this fascinating process!

Thinking about conservation broadly

By Lauren Lewis

I recently had the opportunity to attend a Local Nature Walk in the Inner Sunset’s Green Hairstreak Corridor, a project of Nature in the City. The corridor is a series of nearby small green spaces that are carefully planted and managed specifically to support the presence of the Green Hairstreak butterfly, a nickel-sized, quick green butterfly that’s native to coastal SF. On this particular walk at the end of March, the big crew of butterfly enthusiasts was on the lookout for the first Green Hairstreaks of the season, and we were lucky to spot 2 or 3 while I was there. The spotting moments were full of wonderful nerdy excitement from the group, and very joyous, and it made me feel grateful for this seemingly niche work going on in the urban nature community.

If you pay attention to any sciencey news outlets, and increasingly mainstream news, you’ll notice that the news on insects is dire. The New York Times Magazine recently published a feature piece titled “The Insect Apocalypse Is Here.” The article describes how much insect biomass the earth seems to have lost recently, the challenges of tracking the changes, and humanity’s poor ability to understand the scale and the implications of the losses. Changes are slow and therefore hard to see, and insects are small and seemingly everywhere. In California, the main long term dataset comes from UC Davis professor Arthur Shapiro, whose team has walked transects of central California for nearly 50 years, counting butterflies. His most recent annual summary is dismal.

With these trends in mind, the successes of the Green Hairstreak Corridor and similar projects feels very meaningful. In the Presidio, naturalists recently discovered a bustling colony of silver digger bees, a species that was last seen in SF in any significant numbers nearly 100 years ago. This and other species rejuvenations are attributed to nearly 30 years of habitat restoration work happening in the Presidio- careful removal of non-native plant species and replanting of plants that support a ecosystem more like the one that existed before humans used the land for buildings and roads.

I also recently read “Rambunctious Garden” by Emma Marris, and while it’s now nearly a decade old, the book is still very worth a read if you’re thinking about restoration projects like these. Marris encourages the reader to view conservation not simply as bringing pieces of land back to some old “wild” state (what we think of as “wild” is often wildly inaccurate), but rather something that depends entirely on our goals. Humans have impacted literally every inch of the planet in some way, so when we work to conserve the environment, we must know our specific goal in that instance and work toward it, rather than just reaching for some ill-defined and probably unattainable “wild” state.

For Nature in the City and the Presidio Trust it’s about preventing the loss of once-thriving species, but even within that, you have to ask: why? The answer could be ecological, aesthetic, moral, something else, some of each. No reason is necessarily better than the others, but the key is that we go about the work with thought and intention. The joy of spotting the years’ first tiny butterfly with fellow appreciators might be precisely the goal, and maybe that’s just fine.

 

Mimicking local plant communities in the garden

By Lauren Lewis

In the past I’ve written about the types of plant communities that are local to SF and the benefits we at SSG see in knowing and recognizing our native ecosystems. To connect with those ideas more deeply we can seek to mimic Bay Area plant communities when designing and updating our own personal outdoor spaces. Not only does this approach bring satisfying regional context to our gardens, tying us to our particular place in the world, but it can also result in lower input requirements for the garden- less water, less soil amendment, etc, because the plants we use are well suited to the space.

rtm6yubtsme0koxnmrpcw.jpgTo take this design approach, the critical step is to carefully observe the garden space, or the smaller space within the garden. Regarding sun exposure: which direction does it face? Does it have a slope? Does it have shading elements nearby, like buildings or big trees? Does the space have existing features that will stay, like a tree or large rock? Is the soil sandy, clay, or in between? These factors combine to suggest certain plant communities.

For a space with direct sun and some slope, chaparral or coastal scrub communities make sense. Chaparral is characterized by woody, hardy shrubs like manzanita, ceanothus and toyon, and the color combinations you can get from these shrubs are beautiful. Chaparral is characterized mainly by approximately waist-high plants, with very little low understory. If the garden gets direct sun exposure but is also often foggy then you can veer toward coastal scrub plant choices, which tend to be daintier: coyote brush, lupines, buckwheat. Add in very sandy soil to these characteristics and this suggests a sand dune community, where the plants are shorter still. Beach strawberry, bbej4hsqrqk4kj6rnfm7wg-e1551826450750.jpg
dune sagewort (a variety of artemisia), yellow sand verbena- these plants tend to create a carpet of succulent leaves and bright flowers.

Any fairly sunny spot, but especially a flatter one, would likely support a coastal prairie community, and we love these for their textural diversity and the way we can plant densely. Fescues, needlegrass, lupines, buckwheat (you’ll notice some overlap with the coastal scrub community), and douglas iris all work well here.

For a shady spot, whether shaded from buildings, existing trees, or trees you’ve chosen, you can take advantage of the shade to create a more woodland-leaning feel. Ferns are classic understory plants and they make a garden feel lush. We love native huckleberry and juncus for the mid-height, and for color in the low understory we use flowering shade plants like coral bells, hedgenettle, and yerba buena.

 

Updated Bay Delta Plan and what it means for SF gardens

By Lauren Lewis

In December 2018 the California State Water Resources Control Board voted to update the Bay Delta Plan in an effort to restore habitat for endangered aquatic animals in the delta. The City of San Francisco is now suing the state over the new plan, ostensibly to buy time to work out an alternate plan that is more favorable to water supply in SF but still satisfies the need for more environmental flow. So what exactly is the fight about and what does it mean for water use in San Francisco?

The shortest possible version of the story: San Francisco’s water comes primarily from Hetch Hetchy Reservoir on the Tuolumne River, a tributary of the San Joaquin River, which in turn feeds the San Francisco Bay Delta. So much water gets diverted from the San Joaquin and Sacramento Rivers, for agriculture, cities, etc, that very little is left for “environmental” uses like fish habitat. Scientists argue that 60% of the unimpaired flow (meaning 60% of the water that would flow through the delta if there were no dams and diversions) is needed to support fish populations and their valuable fisheries. The new Plan requires that 40% of the unimpaired flow be restored during Feb-Jun, when it would naturally be flowing, and that will likely mean water restrictions in San Francisco, especially during dry years.

The plan is not yet final due to the lawsuits against it, but however it shakes out there is certain to be a smaller amount of water making its way from Hetch Hetchy to San Francisco. San Francisco is going to have to get more serious about various conservation strategies, like water recycling. If we want to continue being able to grow ornamental plants, there is going to be even more need to take full advantage of the rains when we have them, which means (1) maximizing water infiltration rather than losing water to the drains and (2) planting the right plants in the right places.

For the city, water infiltration efforts means installing permeable paving when possible, and building rain gardens, which you’ll see popping up around the city. For individuals with some outdoor space it means going for soil and plants over hard surfaces whenever possible, and planting the right plants densely. (If pure water conservation was the goal then of course zero plants is better than any plants, but if we’re trying to balance water conservation with our desire to live among plants, then there are ways to do it thoughtfully. Summer-dry adapted plants are key.)

To start taking really good advantage of the rain water we receive, now is the time to be observing in your outdoor space. When it rains hard, watch the way the water moves and collects. You can have a diverse summer-dry garden and still minimize irrigation needs by planting thirstier plants in those places where the rain infiltrates most: the small depressions and low points.

 

What a garden can provide for good mental health

By Lauren Lewis

Scientists have long recognized the mental and physical health benefits that come from interacting with nature. These various benefits were reviewed comprehensively in a recent article, viewed together as an ecosystem service of nature just like carbon sequestration or water filtration. And as we gain understanding of the negative impacts of pervasive screen time, there’s more and more traction for the argument that interaction with nature is actually necessary for strong mental health rather than just a nice-to-have. Here’s a look at some of the bolstering experiences a garden can offer that are elusive in our typical day-to-days (our subjective list).

Physical Work: If your occupation requires a lot of your brain but not a lot of your body, tending the garden is a novel source of physical work. In other words, it’s exercise but with the added satisfaction of accomplishing something external simultaneously. Plus, the external motivation that something needs to get done (the ever-active ivy plant isn’t going to keep itself in check) is powerful for forcing physicality.

Visual Accomplishment: On a related note, garden tasks give us the rare gift of accomplishing something you can see very clearly. Unlike computer tasks, which exist on a finite screen of unchanging size, the garden is full of tangible, changeable elements and the work you put in is clear to see. A weedy tangle transformed by hand into a smooth space is immediate, obvious evidence of your efforts, and there’s unavoidable satisfaction in that.

Feeling of Fascination: Part of the joy of a nature-based excursion is the awe and fascination you can get from an incredible vista or a wildlife sighting. If you live in the city, finding that feeling often means traveling elsewhere (our coasts being a notable exception), but the transformations happening in a garden are fascinating if you pay close attention: the amount of new plant material being created from seemingly nothing, the velvety color intensity of a poppy petal. Our day-to-day lives, almost by definition, lack in fascination and the garden can fill that void if you allow it.