Space Invaders: Dealing with Non-Native Plants
Stamping out Marin's invasive species.
Love plants? Marin County is a stellar place to get a garden growing. Freezing temperatures are rare, winters are short, rolling hills provide wind protection, and it tends to rain here more than inland — all favorable conditions for a variety of flora. Unfortunately, that variety includes nonnative plants that can spread in your yard and neighborhood and into our prized open spaces. Here’s advice for avoiding these troublemakers and getting rid of the ones you find.
Invasive plants are nonnative to the ecosystem and have the potential to cause environmental or economic harm. Typically they’re fast growers, aren’t plagued by disease or natural predators and have many methods of multiplying.
Invasives win the competition against crops and native species for critical resources like water, soil nutrients, and sunlight; plus, they endanger wildlife by forming monocultures (dense stands of one plant) that clog waterways and raise flood and fire risk.
While all of Marin’s natural areas biologically try to defend against invasive species, some have more success than others. Over 300 documented nonnative plant species exist on Mount Tamalpais, for example.
While you may be a conscious gardener, outside actors like birds, animals, wind, and flooding can spread unwanted seeds. Check the invasive plant list at California Invasive Plant Council to see what culprits you might need to remove from your yard.
Root Them Out:
While the first defense against invasives is not to plant them, there are many ways to remove or contain them — manually pulling, weed whacking, hoeing, mowing, tarping and mulching — and using several methods is best. Also research whether your intruder reproduces by seed or by root fragments; that will determine your removal approach.
- Mexican feather grass (Stipa tenuissima)
- Licorice plant (Helichrysum petiolare)
- Pampas grass (Cortaderia selloana)
- Giant reed grass (Arundo donax)
- Running bamboo (usually Phyllostachys species but also Pseudosasa, Chimonobambusa, Arundinaria, Semiarundinaria)
- English ivy (Hedera helix)
- Highway ice plant (Carpobrotus edulis)
- Periwinkle (Vinca major)
- Pride of Madeira (Echium candicans)
IN THE FIELD “Homeowners can create a refuge for native plants, animals and pollinators. Plus, if you see a plant out of place in one of your favorite wildland places, snap a photo of it and submit it to Calflora or iNaturalist; both have apps,” says Dana Morawitz, conservation program manager for the California Invasive Plant Council. She also suggests volunteering with local land managers or neighbors for strategic invasive plant removal efforts — aka weed pulls — and subsequent restoration planting.
Kier Holmes is a native, Marin-based landscape designer who works at M2 Design and Construction, for over 15 years, has artfully designed and created sustainable gardens that are dynamic year round. She also writes for Gardenista, is an elementary school garden educator, a garden speaker for adults and leader of the Garden Club for kids at the Mill Valley Library. Holmes readily admits that she is a nerd about all things plant related, and can geek out on a dinner-plate dahlia like nobody’s business. Her natural habitat is among flowers and her hands are almost always dirty.