Spreading the love: Plants that reseed themselves

I love a free plant. Even better, one that plants itself. I'm talking about reseeding plants, the ones that once done with flowering, set seed and spew forth their progeny with wild abandon.

In garden catalogs they are sometimes politely labeled prolific, yet at other times called out as promiscuous, as with Verbena bonariensis, "a shameless self-seeder."

Of course, there's a fine line between enthusiastic reseeding and downright invasiveness in certain species. I'm as fearful as the next person of "vigorous" (another catalog code word) plants that multiply with underground rhizomes or runners hellbent on world domination. But for the most part, the plants I describe in this column are old-fashioned annuals (and a few perennials) that you can sow once and then enjoy forever.

Self-seeders certainly appeal to the budget-conscious gardener but you might even say these repeat performers help keep a garden sustainable, as they can be depended upon to return with little input from the homeowner.

Left to their own devices, these plants disperse seed close to the mother plant and germinate the following season, leaving no mistake about identification. However, in some cases, the seeds travel on the wind or by bird; humans help out, too, with their watering hoses and leaf blowers often sending the seeds far from their original source.

Without obvious clues to their parentage, these farther-flung seedlings can be harder to identify at first. You may want to delay spring weeding until the tiny plants have developed their true leaves for a proper ID.

Sometimes you may have to let the plant gain some size before deciding if it's friend or foe. And then there are those mystery tomatoes.

For me, I like this element of surprise. A few years back, I could have sworn the late-emerging seedlings around my patio beds were from one of several coreopsis varieties growing nearby. Soon, though, they revealed themselves to be bright purple gomphrena sprung from the previous year's window box. I now look forward to their timely arrival right when those beds need a colorful midseason pick-me-up.

I'm also enamored of the way reseeding plants bring a more casual, cottage feel to gardens. California poppies move around my garden each year, knitting colors and textures together in a natural way that makes it seem not so "landscaped."

While most self-seeders show up where conditions favor their germination — good soil (un-mulched), along with adequate moisture and light — some self-seeders defy this rule, thriving in cracks and crevices. The funny and often unlikely spots where some volunteers set up shop fascinate me. While delicate-seeming columbines are recommended for shade and moist soil, the most robust self-planted specimen in my yard emerged and endures on the hot, sandy edge of our driveway where it's regularly assaulted by our passing cars. Go figure.

I'm also baffled when I attempt to nurture a certain plant from seed and fail, only to find it growing just fine on its own in some forgotten corner of the garden. I attribute this to the exterior elements providing the right conditions to encourage germination that gardeners can only hope to mimic by chilling and/or scarification (nicking the seed).

When self-seeders are too successful, they can become a beautiful nuisance. In my yard, a small drift of 'Lauren's Grape' poppies multiplied into hundreds of silky purple blooms. Thankfully, the seedlings are easy to manage, thanks to their distinctive gray-green color, height and "pull-ability."

You can help the process along with some of your favorite plants; just crush and crumble the seed heads wherever you hope to grow more. Occasionally, folks trim entire stalks with seed heads and lay them across flower beds to encourage new plants. Note that hybridized plants will not come true to type.

If you fear flower proliferation, do the opposite and cut off those flower heads before they can go about reproducing. Dispose of the seed heads in the compost heap (only if it's hot enough to destroy them) or in yard waste bags.

Rhonda Fleming Hayes is a Minneapolis-based garden writer who blogs at thegardenbuzz.com. She is the author of "Pollinator-Friendly Gardening: Gardening for Bees, Butterflies and Other Pollinators," available at Amazon.com.