Sadly, I remember only two things from my studies back in the day at the University of Arizona. The first, from my bug class, is that moths and butterflies belong to the insect order Lepidoptera. The other — which I thought flippant at the time — was told to us by my plant identification instructor on our first day of class: “Weeds are merely plants growing in the wrong places.”
Although these are indeed impressive facts, they have never proved to impress at parties, gatherings, or other social situations and are difficult to incorporate into a conversation around the hummus and brie. However, when I’m at work in the dirt, I do often ponder the second one.
Sometimes, what at first look like weeds coming up all over my garden turn out to be volunteer seedlings from existing or neighboring plants. This seems to be more of an occurrence when we have fall and winter rains or if I use overhead watering such as sprinklers instead of drip irrigation. But nonetheless, I try to remind myself to take a second look before yanking them out.
Once a Good Plant, Always a Good Plant
In some of my gardens, I have welcomed volunteer seedlings from bedding plants such as lobelia, violas, alyssum, marigold, calendula, and false freesia (Freesia laxa), to name a few—especially when those plants have gone to seed and are yet to be deadheaded to remove spent flowers.
Perennials such as milkweed (Asclepias curassavica), ruby grass (Melinis nerviglumis), sweet violet, rose campion (Lychnis coronaria), columbine, wild strawberry, Mediterranean spurge (Euphorbia characias), and lion’s tail (Leonotis leonurus) have shown up uninvited yet appreciated in gardens that I’ve cared for, as well.
I’m always happy to see tomato seedlings show up unannounced when I’ve top-dressed my garden with homemade compost.
None of these above mentioned plant-lets are especially invasive even when they appear in wholesale numbers. Most are easy to remove by selective weeding if they’re blocking a path or crowding out more desirable plants.
When Good Plants Go Bad
On the other hand, sometimes volunteers are not wanted in our landscapes, especially when they scatter seed and germinate in such large numbers that they escape from our gardens and crowd out native species. Fountain grass (Pennisetum setaceum) for example, was and is sometimes still available for sale but is dangerously invasive in our area. All one has to do is take a drive up Foothill Road near Ontare Road in Santa Barbara to see how enthusiastically this ornamental grass reseeds and spreads.
A trip to the nursery will almost always yield a suitable and attractive substitute for an invasive species. “Evergreen” fountain grass (Pennisetum ‘Fairy Tales’) is like “regular” fountain grass’s polite and well-behaved cousin. It doesn’t make a pest of itself and never, ever shows up uninvited.