Some invasive plants are just too fun to pass up. Perennial morning glories, running bamboo, gaura, Santa Barbara daisies… as long as they limit their invasiveness to the garden. Plants listed as invasive in natural areas – things like St. John’s wort and periwinkle – are invasive everywhere, so please don’t use them at all. If your garden is adjacent to a natural area, the last thing you want is for your plants to transform into vegetative commandos that invade and conquer vast areas, eliminating the indigenous population and committing plant genocide.
Some, like the gaura, are related to native plants, and are supposedly a food plant for the white-lined sphinx moth, although somebody needs to tell the moths about this.
The bamboo can be controlled by installing root barriers so you can have your bamboo and eat it, too (the shoots of madake are edible when cooked). Bamboo supposedly thrives on gray water, so you can have an evergreen screen, carbon sucking, edible shoot plant that gets watered every time you wash your clothes – some of which could even be made from bamboo.
Others, like the morning glory, like water and don’t grow well without it. So, by limiting the plants to a wet zone in an otherwise dry garden, they can be kept manageable. The fact that they get killed to the ground by frost doesn’t hurt, either. If you plant this same morning glory in deep, rich soil with regular water, it can cover a vast structure or area almost in less time than it takes to read this, so don’t do it. Really. Just don’t.
The gaura and Santa Barbara daisy reproduce by seeding themselves wherever the soil has been disturbed, but the seedlings are easy to pull out. So we let them seed, decide if that’s where we want them and if so leave them alone. Otherwise it’s a quick rip out and off to the compost heap they go. Sometimes gardeners have no mercy.
Although these plants can spread through a garden or cover a large structure, if they were planted in a natural area where they received only normal California rainfall they would quickly become dead, dessicated twigs and no threat to any ecosystem. When in doubt, you can check a plant here (you can narrow down the search by floristic region, too). Note: it’s better to do this before you’ve fallen in love at the nursery, bought the plant and brought it home.