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.

Surviving irrigation-free

Coleonema pulchrum, a commonly irrigated landscape plant,  growing irrigation-free in Oakland
Coleonema pulchrum, a commonly irrigated landscape plant, growing irrigation-free in Oakland

There are so many plants of the landscape that we assume are water-loving because they are never given a chance to prove otherwise, and because we don’t look into their native growing conditions to see just how little water they need to grow and thrive. Coleonema pulchrum is just such a plant. With its chartreuse leaves and pink flowers, it’s a much-loved plant in Northern California, offering a bright spot within what could be a washed-out landscape of dull greens and grays. Yet what folks probably don’t know is that this plant is native to a summer-dry, winter-wet region of South Africa and thus for many months out of the year has to tough it out with no water.

Indeed, even a drought-tolerant plant will need water up front in order to get established, but once established, the watering can be phased out, and the plant will thank you for it. Plants that are native to regions where drought is simply part of the climate oftentimes simply cannot absorb enough water from irrigation if they are watered during their period of dormancy as their root systems go into a sort of slumber during this time. In a worst-case scenario, their roots will rot, or the plant will grow much larger and faster than it should, ultimately opening out on itself and taking on a leggy appearance that no one particularly likes.

In our inveterate efforts to show that irrigation-free is all around us, we hope that folks will start to open their eyes to other plants they’ve seen growing irrigation-free and doing just fine.

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.”

Rethinking the magnolia

Two dead magnolia trees in Alhambra, California. Victims of drought and a lack of foresight.
Two dead magnolia trees in Alhambra, California. Victims of drought and a lack of foresight.

While past peak, the years-long drought in California is showing its effects in slo-mo delay, coming on in the form of many a street tree stressed to the point of just not being able to take it anymore. Nowhere can this phenomenon be seen more than in Southern Calfifornia, where one of the street trees hardest hit has been the southern magnolia / Magnolia grandiflora. A tree native to the rain-abundant American South, it probably never should have been planted in Southern California at all, where rainfall is typically a scant 12 – 15″ during a good year. But, alas, like so many consumer goods, trees come in and out of fashion, regardless of what practical considerations there may be. So in the ’50s and ’60s street upon street were planted with magnolias in places like Hollywood, and Beverly Hills, and Alhambra – all arid regions and all requiring that the magnolias be irrigated generously in order to survive and thrive. So when the watering bans then hit a few years ago and folks were told to let their lawns and parkways go brown, the trees were never ready for the suddenly parched conditions. Many became stressed, and now, some years later, many are dying. As a result, the cooling shade and outdoor-room-creating canopies will be lost, and we will be left with wide streets and excessive sunlight and heat.

A jacaranda, cactus, and yuccas growing and thriving in hot Riverside County.
A jacaranda, cactus, and yuccas growing and thriving in hot Riverside County.

While devastating for the character of so many neighborhoods and the quality of life of our cities, we need to view this loss of trees as an opportunity to rethink what we plant and how. Even before the drought and worsening global warming, LA was a dry place. This simple truism is not going to change in the foreseeable future, and thus we must start planting trees that can handle these hotter and drier conditions – and that can handle them for the long haul. All it takes is a little observation to see which trees are still pushing on and looking good. In the photo above, you can see that this jacaranda – a tree actually not considered one of the most drought tolerant – and its surrounding plants are doing just fine – more than fine – and this is in hot hot Riverside County, in a parkway space surrounded by heat-absorbing asphalt and concrete. What other trees do you see still doing well? What other trees that you haven’t seen could be invited in, to create amazing tree-lined boulevards for the 21st century? Mesquites, acacias, jacarandas, palo verdes, tristanias – and the list goes on. We cannot keep doing what we’ve always done; it’s simply not working, and we’re seeing our lack of foresight in the form of sadly dying trees and sunbaked parkways. Let’s do better this time around.