You may have heard of “right plant, right place” but have you heard of “right purpose”? Likely coined by Julie Weisenhorn et al. who developed a plant selection tool for the University of Minnesota Extension, this approach seeks to match plants to the conditions they evolved with rather than attempting to fit plants into conditions that may not support their long-term success. By selecting plants according to current conditions (rather than attempting to engineer different conditions), caretakers can greatly increase the chances of plant success and decrease long-term maintenance needs. Furthermore, planning for plants to die out or migrate over time is not only good design but also reflective of a broader regenerative approach to landscape gardening that allows for the caretaker to adjust to conditions as they naturally change over time. Embracing natural change and phasing plants in or out accordingly supports a more resilient and biodiverse landscape.
What is “regenerative” planting?
“Regenerative” is a definitely a buzz word these days, which means you’ll probably find multiple definitions for it across the internet. Put simply, we think of regeneration as the duty that humans have to engage the landscape in ways that extend beyond repair and support and even enhance it. The regenerative philosophy frames human kind as one of many– albeit important– components of the natural environment. In acknowledging how extensive our impact on natural processes and biodiversity can be, the regenerative philosophy suggests humans lean into our influential role to actively encourage the development of complex living systems. ReScape, a San Francisco-based regenerative landscaping workforce development organization, has distilled this philosophy down to 8 practical principles worth exploring here.
Regenerative philosophy suggests humans lean into our influential role to actively encourage the development of complex living systems.
Landscape Planting: Then and Now
Landscaping and gardening values, like most cultural values, change over time. However, some aesthetically-driven values continue to inform our perceptions of beauty and kemptness to this day. Before diving into succession and habitat gardening, let’s explore how we got here first.
Historically, gardens in the western world were a luxury enjoyed by folks who did not have to rely on their land for sustenance. Think: the wealthy nobility of France and England with their strolling gardens and highly manicured lawns. Gardens were designed as extensions of the dwelling’s architecture, continuing lines that imposed order on the landscape accordingly. Highly sculpted evergreen plants represented refinement and a triumph over chaos (nature). Sloping lawns and reflecting pools evoked ideas of infinity and power. Meanwhile, flowering plants were bred to have bigger, fuller, more frequent blooms, a practice that still takes place to this day.
Nowadays, private gardens (or yards) are a thing enjoyed by much of the first world’s middle class. If you’ve ever had your yard designed by a professional, it’s still a common practice to approach the garden as a series of outdoor “rooms” where occupants can enjoy green nature while still feeling the safety and assurance of their home. In this way, residential landscapes are still treated like an extension of the home, so it makes sense that plant and hardscape materials often reflect the owner or tenant’s stylistic preferences. Without any ingrained knowledge of local plants, the average lay person chooses plants they like with little or no practical knowledge of the conditions in which they evolved. The myriad of commercially available cultivars leaves little room to question otherwise.
Understand Your Site
The first step to designing a planting plan is site analysis. Map your site’s existing conditions and, most importantly, how they change throughout the seasons. Most designers can’t do this for you; they will only be able to capture a single snapshot in time whereas you, the caretaker and steward, are developing an ongoing conversation with your landscape. A habitat or biodiversity-focused designer should be willing to visit the site during the winter and summer for a full picture of how the site’s exposure and micro-climates change throughout the year. This is especially important for places around the house and trees so that the changes and shade and sun angle can be directly observed rather than postulated.
The next step is to select plants that have evolved within a location’s set of conditions, rather than the other way around. Since regeneration is interested in enhancing what’s naturally occuring, responding to existing conditions with well-adapted plants (think: natives), rather than creating new conditions, is the name of the game. This idea of planting is also known as successional planting and is well-documented as a small-scale farming practice.
For landscaping, we recommend starting with CalScape.This online database of California native plants can show you what’s native to your exact location (using your address) and tell you the soil, sun, and water needs for each plant. By capturing as full of a picture of the microclimate, soils, drainage, and exposure of specific locations as possible, you can greatly improve the rate of plant success, which decreases waste and reliance on inputs over time. Stronger, well-adapted plants will make your garden more resilient to pests and drought stress over time, which will make them better able to support pollinators and withstand wildlife impacts, too.
Set Succession in Motion
Keep in mind that adding plants (especially trees and larger shrubs) is likely to change the microclimate of one or several plant locations, so having some understanding of each plant’s influence is ideal. For example, most California native soils are nitrogen-poor, so planting nitrogen-fixing plants (i.e. most members of the pea family) outside of vegetable and herb beds will make the site less suitable over time for otherwise well-adapted native plants. Some change is inevitable, but the regenerative approach embraces those changes and asks, “What can this site support now that it previously could not?” Embracing change is an inherently adaptive mindset that can help you to anticipate the domino effects of your tinkering and recognize new opportunities as they arise in your garden. In this way you can begin to allow your garden to mimic ecological succession at the individual site scale.
One way to set the stage for this process is to phase your garden design. Depending on the site’s exposure and soils, it might be worth starting with more grasses or pioneer plants and/or larger plants and trees. This will allow the larger plants time to establish and for the pioneers to build topsoil, giving you the chance to reassess the change in soil and microclimate conditions and to select plants from the next phase that are best suited for the new conditions. This will again reduce waste in the long-run as choices are made in accordance with the direction that the site is shifting.
Another way plants influence a site is through cooperation and competition. We understand a lot about beneficial companions for food-producing plants, but we don’t know as much about how native plants help or hinder each other. However, we do know a bit about which plants are often found together in the wild, which can give us clues as to how to group them in a landscape setting. Along with growth requirements, CalScape also lists companion plants, pollinator relationships, bloom times, and more for every plant entry searched.
Embrace the “Bad” with the Good
It may be worth noting that some changes might not be for the better, in this case, an abundant, biodiverse, and resilient garden. For example, some plants may be too well adapted to a site and might overtake those around it. Contrary to popular belief, it is entirely possible for even native plants to become invasive. To be clear, any plant that spreads easily is not invasive; it’s the degree to which that plant keeps other species from growing and thereby significantly diminishing the garden’s overall diversity that determines if it’s a “weed” or not. Don’t be afraid to be your garden’s guardian; sometimes protecting the trajectory of the whole means weeding out the occasional ill-suited individual.
Be ok with knowing that your garden may take years to reach its “peak”. Make the act of observing your garden a regular practice (dare we say spiritual?). As plants grow, new pockets for later successional plants might open up while others may close. As perennial debris builds the soil, less pest management may be needed but early pioneer plants may die. Keep in mind that working in alignment with processes is an inherently time-consuming thing that pays for itself in the long-run. For this reason, developing a master plan with a variety of plants for each phase (rather than having determined plants in fixed locations) can build-in flexibility. Giving yourself the wiggle room to select species or cultivars that are aligned with your preferences as well as the direction your landscape is moving can ensure the regenerative nature of your efforts while also retaining your individual touch.
Nadja Quiroz operates Mend Landscapes, a member of Pollinate Collective and subcontractor to Habitat Corridor Project and April Owens Design, LLC.
Walking along Santa Rosa creek recently, during a break between atmospheric river events, I was delighted to see Common Mergansers—a male and two females— feeding in the fast-moving creek. Been hearing the Great Horned Owls, too, hooting nightly. Bird activity really starts to heat up in early spring; it’s nesting season. Turns out we have a pair of bald eagles nesting in the Laguna de Santa Rosa and they have produced 14 offspring over a 14-year period. Unlike the Great Horned Owls and the eagles who build their own nests, there are others who are cavity-nesters, and songbirds, in particular, compete for good nesting sites. Nesting boxes are a great way to help out. Check out various bird conservation sites for information on how to build nest boxes or what to look for commercially (nestwatch.org is a good one). Nest hole size, placement, proportions of nest boxes are all important considerations.
Sometimes we want to do something beneficial, like turning our backyard into a wildlife habitat, but it feels too big a task or we just don’t know where to start. The good news: you really don’t have to start over; there are so many ways to make a garden more wildlife-friendly. So where to start? Is there space to add one or more native trees or shrubs? Ceanothus, coffeeberry, hollyleaf cherry, toyon, for example, like sunny spots and are drought tolerant. Do you need a hedge for screening? These plants double as hedgerow options, too, while providing nectar or berries, or both. Can you find room in planting beds for a drift of native perennials or small shrubs? Early spring-blooming native salvias are a great source of nectar for native bees, honeybees and butterflies. Summer-blooming coyotemint (Mondardella spp.), a favorite of butterflies, looks beautiful massed or spilling over a wall. Taking a big-picture view of your back and front gardens, look for ways to increase diversity. Planning for more vertical layers of trees, shrubs, and ground plants will add shelter and nesting places. Plants that produce seeds and berries, fruits and nuts add more foraging sites. A water source for birds can be as simple as a birdbath filled with fresh water. Summer is a good time to see who is showing up in your garden.
There are many ways to attract birds to your garden—water features, plants that offer seeds, nuts, fruit (especially California natives) and plants that provide cover and nesting sites. But If your habitat area is small or you just love watching birds from your window, bird feeders are a way to enhance the experience. Hanging bird feeders that are far enough off the ground to discourage cats and other predators are good choices. Most bird conservation groups recommend feeders that exclude songbird predators such as jays and crows. Equally important is keeping bird feeders clean. Contaminated food, water and feeder surfaces can spread disease among wild bird populations. For this reason, platform feeders are no longer recommended.
If you use hummingbird feeders, be sure to wash them thoroughly at each refill. If you go on vacation and feeders will not be maintained, it is better to take them down than to risk infecting your local hummers.
As co-founder with April of our Habitat Corridor Project, I mostly talk about how to make gardens more wildlife friendly, and the habitat value of native plants. Though I have written more than a few times this past year on monarch butterflies and milkweed, it seems important to highlight some concerns over recent efforts to ban the sale (and discourage the planting of) tropical milkweed. Asclepias curassavica (tropical milkweed) has been banned in several California counties, including Marin, Contra Costa, San Mateo, and Ventura. And I hope it doesn’t happen here. The downfall of the monarch butterfly is a complex issue that many experts believe involves climate change, loss of habitat, and pesticides. In a UC Davis Bug Squad blog (see link below), Professor Hugh Dingle (UC Davis), whose focus the last 20 years has been on monarch butterflies, says that “it is a wasted effort”. Art Shapiro, expert on monarchs for the last six decades at UC Davis, agrees, calling the rationale behind the ban “hogwash”. These two researchers and others believe that winter breeding by monarchs is influenced by warmer winters caused by climate change. Shapiro points out that this tropical milkweed has been planted in coastal southern California for a century, but winter breeding only began about a decade ago. Moreover, another entomology professor at Washington State University, David James, who has studied monarch migrations and breeding in the Bay Area, believes tropical milkweed may be a vital resource for monarchs in a changing climate. The “parasite” question and current research is thoroughly evaluated in this article. I will add this from my own personal experience (and that of other habitat colleagues in Marin County): Without the easy availability of tropical milkweed (at the time), I would not have been able to successfully rear caterpillars taken from a native milkweed that had been stripped. No matter what milkweed a monarch caterpillar starts out on, it can be successfully transferred to tropical milkweed. To read all of the evidence, please follow the link below.
If you are looking to enhance the habitat value of your garden, you won’t want to miss the annual CNPS (California Native Plant Society) plant sale on October 8, 10am-1pm, at the Laguna Foundation, 900 Sanford Road, Santa Rosa. There will be all the usual suspects— manzanitas, ceanothus, coyote bush, salvias, monkeyflowers —plus many more great habitat plants. Here are a few on offer that may be less familiar. Do you have quail on your property or nearby? Quail bush or saltbush (Atriplex) is a fast growing, dense, silvery gray shrub that grows 5 feet or more, and quail love to use it for cover. It’s tough and drought tolerant and tolerates wind and saline soil conditions. Spicebush (Calycanthus), a large bird-habitat shrub I enjoyed immensely at a former garden, is ideal for planting near ponds, along streams or other moist areas. Growing 5-12 feet tall with beautiful green foliage and exotic dark maroon flowers in spring, which are beetle-pollinated, spicebush does best with part shade. Our native red-twigged dogwood (Cornus sericea) is another large shrub that needs some summer water or a moist location. With beautiful red stems that look dramatic in the winter and white flower clusters in the spring, this dogwood provides food and cover for birds and also serves as a host plant for the Spring Azure butterfly. A plant I always look for in late spring on certain trails near the coast is bee plant (Scrophularia). I once planted a drift of this local perennial under a black oak and watched the hummers nectar on the long stemmed tiny red flowers—bee plant is a delightful addition to a habitat garden. Hummers also love the gooseberries and there will be several ribes species available: pink-flowering currant and golden currant. And don’t forget milkweed for the Monarchs! Enjoy!
On July 21 the monarch butterfly was declared endangered by IUCN (The International Union for the Conservation of Nature). Being listed on the IUCN Red List means it is the first time the monarch has been officially considered in danger of extinction. Evidently, there is a big difference in which population —the eastern or the western— is more at risk. Our western population has declined 99.9 percent in the last few decades, from around 10 million in the 1980s to under 2,000 in 2121. The eastern population declined by 84 percent between 1996 and 2014. There was a recent controversial study based on citizen-science data from summer nesting sites that showed an increase in some US locations. However, according to the latest research, it is the winter data that tells the real story. Even if populations rebound in some places in the summer, overwintering populations, whether declining or even remaining stable, are just way too low.
So what to do? As always, plant as much milkweed as possible, because chemically sprayed farmland milkweed, loss of habitat, and overdevelopment of traditional nesting grounds are some of the reasons our gardens seem to be the last ditch resource for our western monarchs. We advocate planting native milkweeds, but if you do plant tropical milkweed, be sure to cut it back in the fall/winter. Tropical milkweed stays green and discourages monarchs from migrating. Cutting it back also helps to eliminate spores that could be on the plant. Climate change has made it easier for tropical milkweed to overwinter in our area. So I repeat, be sure to cut it back. Look for native milkweed plants at our CNPS plant sale this fall. We’ll keep you updated on which species will be available.
It has been encouraging to see so many habitat gardening enthusiasts plant more milkweed and work together to save the rapidly declining Monarch populations. While there was some good news of a significant increase in the overwintering Monarch populations on the West Coast, we are still far from the numbers we have seen in the past. We continue to need more milkweed in backyard gardens, public gardens, undeveloped land—anywhere we can replace some of the milkweed that has been lost to development.
Meanwhile, there are many other local butterflies that are not flourishing. Even if I hadn’t seen news of declining butterfly populations, in general, I would be worried at how many fewer butterfly species I am seeing each year in gardens, on hikes. Unlike the Monarch, some of our local butterflies can lay their eggs on several species of host plants, though they are often in the same plant family. Some of our butterfly host plants are trees or shrubs, such as willows (Mourning Cloak, Western Tiger Swallowtail, Lorquin’s Admiral), oaks (Mournful Duskywing, California Sister), California coffeeberry (Pale Swallowtail, Gray Hairstreak), and mallows (Painted Lady, West Coast Lady, Common Checkered Skipper).
Mallows include shrubs and perennials, and they are easy to grow. Chaparral mallow (Malacothamnus fasciculatus) is a fast growing shrub up to 6 ft tall; island mallow (Lavatera assurgentiflora), which is native to the Channel Islands, is also a fast growing shrub (up to 10 feet tall) with beautiful foliage and showy rose-pink flowers from spring to fall. Though drought tolerant it is happiest at the coast and would need summer water inland. A friend grows it successfully in Novato by planting it near the house, which offers some wind protection. Our native perennial wildflower, checkerbloom (Sidalcea malviflora) is commonly planted as a host plant, but trailing mallow (Modiolastrum lateritum), if you can find it, was always the favorite choice of a botanist friend who inspired me to plant for butterflies many years ago. Mallows, of course, are great nectar plants for all pollinators.
Nancy Bauer Co-Founder - the Habitat Corridor Project and Author of The California Wildlife Habitat Garden: How to Attract Bees, Butterflies, Birds, and Other Animals (UC Press)