California is full of invasive plant species that threaten our wild habitat by outcompeting native species. A native species, by definition is a plant, fungus, or animal species that is not native to a specific location (an introduced species), and which has a tendency to spread to a degree believed to cause damage to the environment, human economy or human health.
While more people are coming to recognize invasive species, there are still so many used and sold in the landscaping trade. Often, with plants such as English Ivy (Hedera helix) people are accustomed to the look and do not know, or maybe care, to find another way to achieve a landscape goal with a more suitable, less destructive plant.
Here is a small list of invasive plants and native alternatives that I would recommend when renovating an existing garden or starting fresh. This selection accounts for invasive plants I still see widely used in gardens, here in Napa County and California in general.
INVASIVE: English Ivy (Hedera helix). As a ground cover it will totally take over and begin to climb up trees and strangle them. The picture above is a perfect example of a tree that must be constantly defended by pulling back the Ivy vines to make sure it survives. It's ugly and requires lots of maintenance. The picture below shows the classic use of English Ivy as an evergreen vine that covers the sides of buildings. This is where this plant becomes so problematic, and predictable, because people want to re-create this 'look' regardless of its negative impacts.
ALTERNATIVES: Heuchera maxima, Island Allum Root as a ground cover. Evergreen, large bold green foliage, and delicate white floral wands make this an excellent native alternative. Vitis californica, California Wild Grape as a climbining vine makes a great alternative with lush green spring and summer foliage, bright orange/red fall foliage and edible fruit. This vine is not evergreen, but its natural twisted vines make for a great winter look.
INVASIVE: Pampas Grass (Cortaderia selloana) is native to Africa and its fluffy seed heads spread everywhere here in California. The grass is very showy, so it has been used a great deal in the designed landscape, thankfully there are alternatives.
ALTERNATIVE: Muhlenbergia rigens, Deer grass is an excellent showy alternative to Pampas Grass. It is also a great habitat builder for the California Quail. This native bunch grass requires very little water and maintenance.
INVASIVE: Calla Lily (Zantedeschia aethiopica) seems to be all the rage on bridal blogs, no wonder it is still being used in gardens, even though it is an invasive spreader in damp woodlands and near precious ecosystems such as riparian zones. It spreads by rhizomes, so digging up the plant to remove it is extra challenging as straggler baby rhizomes are bound to be left behind to re-populate.
ALTERNATIVE: Carpenteria californica, Bush anemone likes part shade to full sun conditions and a little extra water similar to the Calla Lily. It is a native evergreen shrub that offers glossy dark green leaves and amazing Spring blooms of white flowers to be enjoyed similar to the Calla Lily.
INVASIVE: Mexican Feather Grass (Nassella tenuissima) is something I see A LOT in the California landscape, it is especially used quite a bit in the commercial landscape setting (think your local Target parking lot). I understand the appeal, when I first moved to California, I hoped it was native, because it sure was pretty. But alas, this detrimental grass spreads significantly and outcompetes our precious native bunch grasses.
ALTERNATIVE: Bouteloua gracilis, Blue Grama Grass offers a similar airiness that Mexican Feather Grass claims, without taking over. This native grass can be used to create soft drama in the landscape, or even be a great low-water lawn alternative.