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.

When a forest isn’t a forest

A prairie savannah in what had recently been forest in Phil Hardberger Park, San Antonio, TX. Photo from the Phil Hardberger Park Conservancy.
A prairie savannah in what had once been forest in Phil Hardberger Park, San Antonio, TX. Photo from the Phil Hardberger Park Conservancy.

We so often think that forest is the natural result of just letting nature be and that to see forest is to see an indication of a healthy ecosystem. Yet we forget that many ecosystems are actually not forest-based at all, or else they are a mix of forest and other types of ecologies, such as grasslands and prairies. Years of fire suppression and mismanagement in the US have actually allowed many formerly grassland and savannah (mix of grassland and forest) ecologies to become completely dominated by forest, which is then often dominated by one or two species that have simply outcompeted everything else.

This scenario was very much the case within what is now Phil Hardberger Park in San Antonio. Years of fire suppression, grazing, and dairy ranching on the site had turned what had once been prairie, prairie savannah, and some forest, into basically all forest. So embedded had the forest look and feel of the area become that within the local narrative of the place people simply saw it as natural and having always been there. Recently, when the site was to be re-envisioned as a park, designers and ecologists had to contend with vast stands of juniper that had worked their way in and basically choked out native grasses, oaks, and perennials.

This foresting of places that were never forests to begin with is nothing new in American history. In fact, much of California was grassland before European settlers arrived. In his book, Trees in Paradise, Jared Farmer writes that settlers coming to the Far West wanted to “complete” the land by foresting it. “They forced grasslands and wetlands to metamorphose into fields, orchards, and garden cities,” he writes. To use a term of the time, they “emparadised” it. These longstanding efforts, combined with years of fire suppression, have transformed parts of California into hybrid manmade-natural tree-dominant ecologies that didn’t exist prior to the arrival of the Spanish some 450 years ago.

Of course, the lessons we can learn from these examples are not that trees don’t have their place in spaces where perhaps they once didn’t grow. Our urban and suburban landscapes are brimming with things that didn’t used to be there – pavement, right angles, roofs, to name a few – so to make the case that trees shouldn’t be there because they weren’t there before doesn’t really hold water. Not to mention that we need street trees more than even, given the realities of the urban heat island effect and climate change. Yet when it comes to our less urbanized and wilder spaces and places, rethinking the role of the tree in ecologies that were not ever forest is a much-needed endeavor. To restore these places back to prairie or Savannah is a way of ensuring that they are able to grow and evolve in a way that ultimately reaches a balance, so that one species – such as juniper – doesn’t become so dominant as to prevent biodiversity from flourishing. As a result, intense, long-term maintenance of the space does not have to be a prolonged and expensive reality.

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.”

Goldenrod, a sign of now

An illustration of goldenrod from the Macmillan Wildflower Book, 1954
An illustration of goldenrod from the Macmillan Wildflower Book, 1954

Late summer and early fall in much of the country are characterized by golds and purples, if you know where to look. In fields, prairies, vacant lots, and roadsides, the gold of goldenrod makes its determined and brilliant appearance. Growing from spring through summer, slowly sending its flower buds forth, it finally bursts into explosions of gold when many plants have long finished flowering and are already getting ready to slow down for winter. Bees and butterflies then flock to its flowers, stocking up on pollen and nectar before hunkering down or flying south. And then, just like that, the spectacle of color is over – or seemingly so – as a new spectacle then appears: birds, coming to feast on the seeds.

While some goldenrods do look a bit on the weedy side at times, we can forgive them for that, because everything else about them is, well, golden. For further reading, we cannot think of a better writing on this amazing plant and flower than the poem “Goldenrod” by Mary Oliver. You can read that here.

Plants as magnets for the good and bad

Observing the Joppa Avenue Landscape in Minneapolis, Minnesota, for bees, butterflies, and bunnies
Lounging and observing the laboratory

The occasional sad reality of doing landscape design is that not all landscapes you create will survive long-term. Ownership can change, and maintenance can be spotty. At the very least, you can expect that some plants will die or be less successful than planned due to circumstances outside of your control, and the result will be a landscape different than what you had envisioned. In our case we never could have anticipated the bumper crop of rabbits that seemed to emerge in Minneapolis in the summer of 2009, or how that bumper crop would subside by 2014. Nor could we have anticipated how much the monarch and honeybee populations would dwindle during that same period. Fortunately, we’ve had a living laboratory of sorts in which to observe all of these phenomena long-term and to see what plants are bunny magnets, and which are monarch and bee magnets.

Here is our run-down:

BEE/POLLINATOR MAGNETS
Nepeta x faassenii ‘Walker’s Low’ / Walker’s Low catmint: Blooms for at least a month (reblooms after a mid-summer haircut), with the bees (bumble, honey, and solitary, not to mention hoverflies, hummingbird moths, butterflies, and hummingbirds) on it from sunrise to sunset
Aster oolentangiensis / sky-blue aster: Very good late-summer nectar/pollen source
Solidago speciosa / showy goldenrod: Also an ideal late-summer nectar/pollen source
Diervilla sessilifolia ‘Butterfly’ / Butterfly bush honeysuckle: Bumblebees love the little yellow flowers; lightly cut back after blooming for a second bloom
Perovskia atriplicifolia ‘Longin’ / ‘Longin’ Russian sage: Bees of all varieties love this plant, and it blooms from July virtually til the end of summer
Sedum ‘Autumn Joy’ / Autumn Joy stonecrop: Amazing late-summer nectar/pollen source

MONARCH MAGNETS
Liatris ligulistylis / meadow blazing star: They bloom, and the monarchs come. . . in droves; it’s as simple as that
Eutrochium purpurea / Joe Pye weed: Huge, tall, and full of monarchs once they bloom in July
Verbena bonariensis / Brazilian verbena: An annual that blooms from June (depending on when you plant it) until the end of summer and thus provides a very consistent nectar source for monarchs, which flock to it

RABBIT MAGNETS
Echinacea purpurea / purple coneflower: Numbers dwindled down to almost none by 2013, have replanted new ones and caged them
Panicum virgatum / switchgrass: Ultimately disappeared after two years and space taken over by other plants
Sporobolus heterolepis / prairie dropseed: Initially took a huge hit from the rabbits but now seems to be doing better now that it’s been in the ground longer (maybe rabbits don’t like crusty old grasses?)
Koeleria macrantha / June grass: Suffers some damage by rabbits each year in the spring, becomes less attractive to them by July
Rudbeckia hirta / gloriosa daisy: Numbers dwindled down to almost none by 2012; some that had self-sown in cages around other plants managed to survive, and now the landscape is full of them again (but there are also fewer rabbits now)
Liatris spicata / dense blazing star: Caged them and the rabbits have since kept away; landscape now dense enough that the plant has self-sown here and there, and the seedlings seem to be protected by other plants (that is a very loose hypothesis based on casual observation)
Aster oolentangiensis / sky-blue aster: Some were gnawed down to the ground and died; remaining ones caged and are now thriving and self-sowing with a bit too much aplomb
Liatris ligulistylis / prairie blazing star: A choice meal of rabbits of all shapes and sizes; the plants need cages around them if they are to survive a rabbit’s dinnertime whims

Just to be clear and in layman’s terms: bee and monarch magnets will bring you happiness; rabbit magnets, without the proper protection, will bring you sadness.

John Kamp