Ecological Garden Design - Part II (Pollinators)

By ​Felicia Fredd
Xtreme Design SW

In Ecological Garden Design - Part One, I introduced Douglas Tallamy’s proposed Four Universal Landscape Ecological Goals. Dr. Tallamy, a conservation entomologist at University of Delaware, has spearheaded initiatives to promote ecologically oriented home landscape and garden practices which, he says, “… must now take a leading role in the future of conservation.”

“Our parks and preserves are vital, but … they are not large enough and are too isolated from each other to sustain for much longer the plants and animals that run our ecosystems.” Doug Tallamy, https://www.karenbussolini.com/restoring-insects-to-our-landscapes-every-yard-counts/

Tallamy’s Four Universal Landscape Ecological Goals address critical and interrelated aspects of landscape ecology as understood by an ecologist, but in a short form organized for a simpler understanding. The first of these goals is that they “must support a diverse community of pollinators throughout the growing season.”

On this point, I found myself wondering such things as ‘How would I even know if I have a diverse community of pollinators?’, or ‘What exactly do the most special ones need throughout the growing season?’ After spending some time looking at various urban ecology studies, and their conclusions, I think it’s safe to say that although very interesting to ponder, such questions really aren’t that productive for the average non-scientist like myself. What does matter is that anyone interested in ecological gardening get familiar with their local native plants, especially local ‘keystone’ species, and perhaps some of their relative value to native pollinators. The rest naturally follows.

In a nutshell, a functionally valuable ecological garden within it’s own special ecoregion, and micro-climate, would fundamentally look like, or be, a version of the closest surrounding example of undisturbed landscape in terms of native plant composition - all the way down to cryptobiotic soil. It’s almost that simple, and if you can pull off something like that you’re golden. Ecological gardening all relates back to the native plants that have coevolved with the native wildlife and pollinators (bees, butterflies, flies, wasps, beetles, bats, etc.) to survive within their soil and climate niche(s).

“Native plants are core to the wildlife garden. Intentional use of native plants, which have formed symbiotic relationships with native wildlife over millions of years, creates the most productive and sustainable wildlife habitat. While some plants play a singular role for one or limited types of wildlife, others are essential to the life cycle of many species. The local species of these plants vary by ecoregion, that is, areas where ecosystems (and the type, quality, and quantity of environmental resources) are generally similar. Keystone plant genera are unique to local food webs within ecoregions. Remove keystone plants and the diversity and abundance of many essential insect species, which 96% of terrestrial birds rely on for food sources, will be diminished. The ecosystem collapses in a similar way that the removal of the “key” stone in ancient Roman arch will trigger its demise.” https://www.nwf.org/Native-Plant-Habitats/Plant-Native/Why-Native/Keystone-Plants-by-Ecoregion

So, the very first thing you can do for landscape is to protect what’s naturally there, and not replace existing plants with something “better” (except invasive plants/weeds). For abused, damaged spaces, the second best thing is to recreate what is around you, or ‘rewild’, as best you can (beginning with eliminating invasive weeds).

I’m particularly interested in how visual ‘framing’ and simple augmentation of preferred natural landscape features through design can help make rewilding and wild chaos, or even perceived ugliness ‘interesting’ and/or beautiful. There’s a really great article on visual framing here by Joan Iverson Nassauer here: https://drive.google.com/file/d/1U9NexhxJB30NLVKqBCut7_aQH_5JcH06/view

For what are essentially garden spaces that will see ongoing human cultivation, there are a few additional pointers. These are special environments that ecologists are particularly interested in because they have increasing value as surrogate native habitat for that which has been, or will be permanently destroyed.

1) Bringing in pollinators begins with not destroying them through so much harmful maintenance: fall and spring clean up should be light (insects overwinter in plant debris); pesticides should be avoided; weedwacking should be avoided, etc.

2) Try to follow the 70/30 rule: Limit non-native plants to 30% of cultivated space. It seems that this same 30% should be targeted at providing nectar flowers during midsummer when wild plants are less productive with flowers. Maybe it’s your herb and veggie garden (mostly non-natives in this category) to native vegetation ratio. Whatever that looks like, it’s important for insects to be able to complete their lifecycle(s), and yes they can die of starvation.

3) Don’t take things too strictly, or quickly, and rip out healthy non-native plants because something has been put down as a general rule. Even a nice old healthy ‘trash’ tree such as an elm might be providing something very important for the time being. Lawns are not automatically wicked.

4) Be aware that the more elaborate hybridized flowers (double or more petal sets) are generally less useful to insects.

“Several studies have shown that the explosion of petals that may delight gardeners can actually reduce the attractiveness of that flower to pollinators. This may be a result of lower nectar production as the plant puts its energy into making petals or it may be simply that the insects can’t get to the nectar or pollen. If you think a beautiful flower is one with a bee or butterfly on it, choose the simpler single blossoms as you make your plant selections.” https://extension.oregonstate.edu/gardening/pollinators/less-showy-flower-petals-mean-more-pollinators

5) Outside of invasive species, no one is saying that non-native plants are BAD, just that native plants are better from an ecological standpoint.
One trick I’ve found that helps people tolerate some of the more wild and rangy natives is to combine them with closely related ‘nativars’ or with similar but fancier genera. I guess it’s kind of like hiding the monster in a pile of plushies. Planting a slightly ‘weedy’ looking Velvetweed (Gaura parviflora) with Whirling Butterflies (Gaura lindheimeri), or planting basic annual sunflower with a fancy hybrid sunflower works beautifully .

6) Layer. This happens to capture some seasonal patterns of dominant pollen sources as well. Taller fruit/nut producing trees and shrubs tend to flower first in spring. Here, that will be things like chokecherry, golden currant, serviceberry, new mexico privet, cottonwood, oak, willows, boxelder maple, wild plum, silver buffaloberry. In late spring-midsummer, it seems the wildflowers dominate. Some important ones are: penstemon, coreopsis, milkweed, clover, globemallow. In Fall, it seems many of the rangeland shrubs like chamisa, sage (all types), and snakeweed are taking over in flower and pollen production.

Marilyn Phillips of The Abiquiu News Bloom Blog put together a great image catalog identifying local native flowering by month - linked here: https://www.rockymountainsflora.com/news/abiquiu/abiquiu-july.html. It’s a great tool because it allows someone less familiar with plants by name to explore ecological design planning with plants in bloom and serving pollinators across the months of the growing season. It’s just so much better than trying to decipher descriptives like ‘early spring’ or mid-summer’. We need more of this.
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Also, do check out one version of the Homegrown National Park keystone species by ecoregion chart here: https://www.nwf.org/-/media/Documents/PDFs/Garden-for-Wildlife/Keystone-Plants/NWF-GFW-keystone-plant-list-ecoregion-10-north-american-deserts.pdf. It’s really interesting to see how many insects depend on native plants.