Drought-tolerant vernacular

An everyday resident of Colton has planted their trees in drought-busting watering basins
An everyday resident of Colton has planted their trees in drought-busting watering basins

The watering basin is a planting technique in which the plant or tree is not planted at ground level but instead is sunken so that water is directed downwards rather than away from the plant. As a result, the plant’s roots grow deeply rather than superficially. As an added benefit, the basins both catch rainwater and make deep watering by hand much easier. The technique is a hallmark of the irrigation-free landscapes we do, and, lo and behold, is something that just an everyday resident of Colton, California, has been doing too (see photo above).

And yet, when I first shopped this planting idea around to landscape professionals and arborists when we were pitching the irrigation-free idea, I was told by many that this was bad practice. Once we had secured public funding for the pilot Irrigation-Free Landscape and I was in the thick of installing it, there was actually a professional landscape designer working on the landscape next door. While I was planting one of numerous grasses in the basin-style of planting, she came up, grabbed the plant by the crown, and said, “Why are you planting it this way? Don’t you know you are supposed to plant the crown just above soil level?” I said that I was, but above the soil level of the bottom of the basin. She was not convinced. In another conversation with an arborist, I was told that you could not plant trees in this basin style, because their roots would grow out and around and eventually girdle the trees.

In fact, within educational materials and at workshops put out and on by professionals working in the realms of sustainability and landscapes, the watering basin is simply never suggested. Rather, you are to plant your drought tolerant plants in the same way you’ve planted any other plant, and you are to still tether them to an irrigation system. In short, within the worlds of landscape architecture, design, and arborists – the professionals one would think would be at the forefront of real techniques for sustainability – there is at one end a limited take on designing for drought, and on the other, outright resistance to new techniques.

The truth is, landscape professionals and designers can be woefully unwilling to step down from their lofty seats of professionalism and advanced degrees to look at what everyday people are doing in their own landscapes when responding to drought – both in terms of planting technique and design. No, this is not to say that landscape professionals know nothing; rather, it is to say that we don’t have all the answers. No one does. And sometimes those answers lie within the work of non-professionals and what kinds of drought-tolerant vernacular landscapes they are making.

And so we come full circle to this resident in Colton, who clearly understood on an intuitive level that given low rainfall and high heat in a place like Colton, planting the trees in basins makes perfect sense, and the resident’s work has resulted in plants that are surviving and thriving.

-John Kamp

The little plant that could

Mystery plant spotted and observed in Oakland growing and still green with no irrigation for months
Mystery plant spotted and observed in Oakland growing and still green with no irrigation for months

We spotted this plant back in May, appearing seemingly out of thin air and looking surprisingly un-weedy for being a volunteer. Since then, it has grown without irrigation for months, and has stayed remarkably green too, not once showing signs of drought stress. The thing is, we have no idea what this plant is. We are waiting for it to bloom to have a better clue of what it might be. In the meantime, we’ll marvel at its toughness and its ability to plant itself in horrendously compacted soil and thrive all summer long on basically zero water.

Once again, plants growing and thriving irrigation-free are all around us. We just have to open our eyes and look.

Irrigation-free all around you

A Verbascum bombyciferum growing irrigation-free in an alleyway in Oakland, at the end of the dry season
Verbascum bombyciferum growing irrigation-free in an alleyway in Oakland, at the end of the dry season

When we say we do irrigation-free landscapes, we typically get one of three responses: 1. That can’t be done; 2. That’s been done before; or, 3. How cool. We love the third, of course, but the first and second responses do merit a conversation.

When it comes to the first, all it takes is a bit of observation just beyond your front door to see that there are plants growing irrigation-free all around us. The above photo is of a couple Verbascum bombyciferum plants growing totally irrigation free, at the tail end of the dry season in Oakland, California. And this isn’t the only one. We’ve seen canary palms, lavenders, four o’clocks, coleonemas, calla lilies, and more, growing irrigation-free and looking just fine.

Once we have seen and observed these lovely tough ones doing their thang, we should ask ourselves what we can learn from them, so that we might either use some of them in our own landscapes, or find ones better suited to the space in question and our aesthetic tastes but that have the same drought-busting qualities that these do.

As for the second response, the dismissive one of “Oh that’s been done before” – well, in part they are right. Nature has been doing irrigation-free for milllenia. Yet as far as actual gardeners, landscape designers, architects, contractors doing irrigation-free in more cultivated landscapes – especially in the US – we have seen very little of it. The drought training, the watering basins, the right plants, the rainwater harvesting, the monitoring of how much water each plant gets, all in one landscape – we’ve done this, yes, and very successfully in our pilot landscape. Brad Lancaster has done much with rainwater harvesting and contouring in his, and there is some truly forward-thinking stuff going on in Tucson. But we have seen little beyond this, especially in a place as supposedly forward-thinking and progressive as the Bay Area, where we are actually light years behind when it comes to both stormwater retention and truly drought-tolerant landscapes. Most of our rainwater ends up running into the Bay, and virtually all of our landscapes are tethered to irrigation systems – even the drought-tolerant ones. In other words, we have a long way to go. In any case, though, if it has been done, well, it couldn’t hurt the planet to have it be done much much more.

In the meantime, we as Prairieform will keep giving presentations on irrigation-free landscapes (most recently at the University of East London and UC Davis), make those landscapes a reality, and keep chugging forward, finding those folks whose response is refreshingly, “How cool.”

Hope

dwarf fritillary butterfly caterpillars on passion vine in Oakland, California
Dwarf fritillary butterfly caterpillars on passion vine

In 21st-century California, it is increasingly a luxury of kingly proportions to have a yard of one’s own, especially within one of the state’s major metropolitan areas. As such, container gardening is the only option for many of us, a type of gardening that presents its own set of challenges, not the least of which being watering, as even the most drought-tolerant of plants will require much more watering in a container than they would in the ground. Maintenance reservations aside, I bit the bullet some months ago and started transforming the fire escape/balcony we have here in Oakland into a pollinator garden that is ideally groovy to look at and hang out in as well. To these ends, I planted, among other ‘tings, three kinds of passion vine back in April, hoping to attract the dwarf fritillary butterfly, whose food of choice is the passion vine. Well, as of a month ago, I discovered tiny orange eggs on the vines, and then two weeks ago, these eggs hatched into the tiniest of caterpillars. Since then, the caterpillar children have eaten to their hearts’ content and grown exponentially bigger by the day.

It would be a cliche to say that these are uncertain times we are living in, but, well, the cliche rings true. And in such uncertain times, inviting wildlife intro your landscape in whatever way possible can be a tonic to the lunancy about, serving as a small beacon of hope. What’s not to marvel over that a tiny butterfly would fly around and somehow locate a little patch of passion vine in the middle of dense, urbanized Oakland and decide to make that small patch of green home for its butterfly kids? It is marvel-worthy indeed.

John Kamp

Wantonly Weedy Wednesday

Acacia melanoxylon, or black acacia, found growing between curb and concrete on Adeline Street in Berkeley, California, completely irrigation-free and mid-drought
An Acacia melanoxylon / black acacia seedling found growing in the crack between a curb and a concrete slab in Berkeley, CA

While hated by many for its invasiveness, it’s difficult not to marvel for just a moment at the multi-toned, variegated, and delicate beauty of an Acacia melanoxylon / black acacia seedling. You might marvel even more if you knew that this particular seedling shown above was found growing between the curb and a concrete slab of an unirrigated median on busy, traffic-soaked Adeline Street in south Berkeley (otherwise known as Quadrant B of the Vacant Lands Broakland Study Area). This is true tenacity.

How this seedling made its way to this particular spot is anyone’s guess, but an 1858 seed catalog might hold the key. It was brought from Australia to England in 1819 and was one of the first Australian plants offered for sale in California. William Walker was the first Californian to make it commercially available in his 1858 Golden Gate Nursery catalog. And now the tree can be found growing not only in California, but also in Africa, Asia, Europe, South America, and the continental US – a vast range in large part due to the plant’s knack for self-sowing with abandon and being able to grow and thrive within the toughest of conditions – from drought, to smog, to everything in between. Far from being a mere survivor, the tree is actually prized for its wood, both as durable lumber and as the raw material for something more decorative – say a chair, or, perhaps, a chaise.

Final tidbit of Acacia melanoxylon trivia: it goes by many more accessible, some might say sassier, names: Sally wattle, lightwood, hickory, mudgerabah, Tasmanian blackwood, black wattle, or blackwood acacia.

John Kamp