7 minute read
Grassroots Conservation: Reinventing the Lawn With California Native Grasses
By Keith Nevison, Director of Horticulture and Facilities
During wet years, we Californians breath a sigh of relief when winter’s rains fill our creeks and reservoirs, greening up hillsides and hydrating our thirsty plants and grasses. But as we all know, weather patterns change dramatically in our notoriously unpredictable state, especially in the era of climate change. For this reason, it's important we tune in to the dry years as well. Regardless of what the weather is like today, we need to prepare our landscapes and lawns for the impact fluctuating weather has on our home and community spaces. Our ability to sustain multipurpose landscapes requires that they use less water while still being welcoming to native fauna and humans. Enter native grasses and lawns.
Grass Knowing and Growing
Having evolved in the Golden State, native grasses are typically adapted to use less water than conventional turfgrasses — a huge plus. Nonnative grasses (first imported from Europe, Asia, Oceania, and Africa) are often water guzzlers, using up much precious irrigation that is sometimes delivered from hundreds of miles away via the California system. What often overrides that deficiency is that nonnatives can handle heavy foot traffic better than natives, leading them to be favored as recreational turf surfaces in parks, schools, commercial areas, and residential yards. But residential yards have different use patterns than public spaces. Native grasses certainly can be a great addition to the home landscape, where small patches of grass are desired for pets and kids, occasional picnics, or framing out planting beds to showcase California’s beautiful native perennials, annuals, trees, and shrubs.
Experimenting With Native Lawns
Well aware of the copious need for supplemental irrigation to be applied to nonnative turf, Santa Barbara Botanic Garden decided to plant three distinct lawn zones in our Island View Section in front of the Pritzlaff Conservation Center (PCC), just after its construction in 2016. Since this time, two of our “lawns” have performed rather well: blue grama grass (Bouteloua gracilis) and clustered field sedge (Carex praegracilis). Both have held up decently to numerous pets and humans, yoga classes, weddings, Summer Serenades, and other events held throughout the year, though both have required occasional (sometimes frequent) interventions of heavy compost applications, reseeding, and weeding out dandelions and other weedy interlopers. Our third "grass" section has been more of a journey. In the past, it supported a low-growing perennial groundcover, kurapia (Phyla nodiflora), which is rather oddly listed as being native to both the United States and Brazil. When our kurapia section ultimately failed under persistent foot traffic, it opened up an opportunity to test a native, cool-season seashore dunegrass (Agrostis pallens). This grass species has limited evaluation in the landscape and nursery trade, but so far, we are seeing okay results, after its first full growing season. It reemerged this spring with the promise of a strong second growing season after its planting in June 2023.
The PCC isn’t the only place where you’ll find a native-grass lawn. The south side of Caretaker’s Cottage sports a blue grama grass patch for the Home Demonstration Section. This lawn display was installed in 1991, and has performed admirably well, being less subjected to foot traffic. In this instance, one can see the true longevity of a native lawn, with lighter daily use.
All in all, our results at a busy, public-facing garden open 362 days a year are a bit lackluster. However, it does hold up well enough to regrow year after year, and it provides guests with a soft surface on which to walk their dogs or hold a downward dog pose. What one might expect on their less-heavily-traversed home turf could be even more encouraging.
Could a Rare Grass Redefine the Everyday?
While we would be fine tending only to our three distinct graminoid zones (fun fact: a graminoid is a grass or grass-like plant, which includes sedges and rushes), we at the Garden are always curious to study native plants for novel applications. In pursuit of this, the Garden applied and was awarded a 2023–24 Saratoga Horticultural Research Endowment grant to collect, plant, and evaluate a state-listed rare grass species, Hoover’s bentgrass (Agrostis hooveri), for its potential for introduction into the landscaping and horticultural trades. In the wild, Hoover’s bentgrass is very rare and moderately threatened (1B.2 statelisted), isolated to just Santa Barbara and San Luis Obispo counties, with fewer than 20 known populations, and apparently still declining. As a rare plant, not much is known about how to successfully propagate and establish this grass in landscapes. This led the Garden to choose it as an experimental species to see how it performs in nursery pots and in ground, and we will potentially subject it to foot traffic, pets, and recreational activities to test whether it could be recommended as a turfgrass alternative species. As already noted, it is typically held that native grasses don’t perform as well as nonnatives under heavy foot traffic and that native grasses and sedges can be a good substitute for areas with only light foot traffic; however, I’d like to highlight an additional overlooked point that native grasses and sedges support more native wildlife species than their nonnative counterparts! For example, Hoover’s bentgrass is suspected of supporting four species of native moths and skippers. Commonly planted and/or escaped nonnative Bermuda grass (Cynodon dactylon) or ripgut brome (Bromus diandrus) haven’t been observed supporting any native lepidopteran insects, key to supporting the diet of local songbirds. In fact, the spread of nonnative grass and other plant species into natural areas can easily lead them to outcompete and suppress native plants, contributing to a worsening state of invasion in our natural ecosystems. Let’s steer clear of these nonnative grasses!
The More Graminoids and Forbs, the Merrier
While the Garden has historically opted to grow singlespecies lawn monocultures to test how well they establish and perform, an alternative approach could involve a lawn polyculture. This would feature a mix of graminoids and low-growing forbs (herbaceous, flowering, non-grass plants) to form a tight-knit planting that functions similarly to turf, providing recreation with a promise of habitat. Colleagues at Cornell Botanic Gardens have had success with this approach, albeit with a significantly different climate in Ithaca, New York, versus Santa Barbara, California.
If you are still leaning toward single-species options, the California Native Plant Society has a nice article by Audrey Pongs describing “Native Grass Alternatives to Lawns.” She offers two different approaches of working with meadow plants versus installing lawn replacements.
How Water Usage Weighs In
Water usage is a hot topic in California — and all this talk of turfs and lawns can’t help but circle back to water. An estimated half of all water use in California’s homes currently goes to irrigate landscaping. From a commercial standpoint, the recent 2023 passing of Assembly Bill 1572 declares that “the use of potable water to irrigate nonfunctional turf is wasteful and incompatible with state policy relating to climate change, water conservation, and reduced reliance on the Sacramento-San Joaquin Delta ecosystem.” I believe pressure will mount to convert more nonnative residential lawns to landscapes that require less water, and it seems logical that commercial landscapes will follow suit.
Gracias, Native Grasses
Let’s look to native grasses to help ease these transitions. For residences, they can provide soft, pervious walkways that frame planting beds and allow for human and pet traffic. For higher-traffic areas, the Garden will continue pursuing, studying, and experimenting with native grasses, in search of the hardiest native turf options. You can look to us to keep educating guests and promoting the conversion of nonnative turf to spaces that are beautiful, functional, and beneficial.
