Notice how the trees are planted in the 17th-century Patio de Los Naranjos in Cordoba, Spain – in basins and connected by way of channels. No overhead emitters; no automatic sprinkler system. Just plants planted slightly sunken so that water can percolate straight down to the roots of the trees, drawing the roots down with it.
Many a landscape professional has looked on in horror when we have proposed or used this technique in our landscapes; and yet, here it is, time-worn and tested, the trees clearly thriving and growing well.
We need to start rethinking our planting practices and the notion that a landscape must have an irrigation system of emitters and lines and tubing in order to survive. The Patio de los Naranjos is yet more evidence of why this just isn’t so.
What is so fascinating about this documentary on Southern California’s Descanso Gardens is that it really traces the evolution of our understanding as a culture of nature, ecology, and gardening. And this evolution can be seen through what the Gardens have prioritized and modified over the years – such as moving water-loving camelias (the early cornerstone of the Gardens) away from the live oaks (which hate summer water), and an increasing focus on water conservation and habitat landscaping. The documentary even weaves in the ugly history of Japanese internment, its connection to the Gardens, and how that story, once buried, is now told very openly.
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.
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.
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.
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.