As much as I love the controlled chaos of sowing seed pots—the desire to grow bridled by little plastic cubes that make my young plants so easy to pop out and place just where I’d like them—I must admit it isn’t nature’s way. Nature’s way is something like Darwin outlined: an intersection of chance, genetic aptitude, and opportunism. This is how the forest floor is gardened, how a meadow gets planted, or a rockface, a riverbank, the cracks of a sidewalk. As much effort as we put into making it otherwise, the same forces are at play in our own gardens.
Someone once told me, and I’ve heard it said many times since, that a weed is just a plant that pops up where you don’t want it to be. As all gardeners know, flora we intentionally plant may also prove a bit weedy for our tastes (foxglove, hellebore, many ornamental grasses, to name but a few). Even the vegetable plot sometimes gains a confidence of its own, sprouting seedlings without express permission. While a dandelion is almost always a weed, we often call these little upstarts “volunteers.”
Some vegetables are more likely to voluntarily emerge than others: tomatoes and cucurbits are common. In the height of summer, fruits drop; if we don’t pick them up, they rot, leaving primed seeds behind. Lettuces, brassicas (like kale or mustard greens), arugula, sunflowers, and cilantro are equally prolific if your harvesting habits allow them to reach seed-bearing stage. I’ve never dug up a potato patch without inadvertently leaving behind a few tiny spuds that inevitably re-sprout the following spring.
So it goes. If allowed, your garden would start gardening itself. Some gardeners suppress the garden’s urge to volunteer, others are charmed by it. Where you stand on the scale between methodical and improvisational is a matter of personal preference. I’ve envied both bountifully tidy garden rows and those described by Masanobu Fukuoka, a 20th Century Japanese farmer and writer who pioneered his own eclectic brand of natural farming. Fukuoka planted his un-tilled fields using seed balls, a method that capitalizes on the spirit of volunteerism. Seed balls contain a variety of seeds rolled into little clay globes that the farmer chucks into their fields at just the right time (when the cover crop has died down and weed competition is at its lowest). Those that land in an opportunistic place will, in theory, grow to be robust, drought-resistant plants.
Though seed ball planting is not necessarily the best choice for residential gardens (or any garden desiring specific levels of productivity), it’s a useful metaphor for what we are always doing when we garden—throwing our seeds into the ring and hoping they have a fighting chance. Volunteers are accidental victories, and because they made it through Darwin’s qualifying rounds, they deserve consideration. Not surprisingly, volunteers often end up being highly productive, vigorous plants. Unlike transplants, their roots never felt the shock of moving from one environment to another, nor were they ever stopped in their downward descent by the bottom of a plastic pot.
Equally unsurprising is that volunteers are unpredictable. Most tomato seeds will grow back true to type; volunteers sprouting where you grew that cherry variety last year will likely grow up to be the same cherry variety. Cucurbits, like zucchinis and cucumbers, often do the same, especially if you only planted one or two varieties the year before. However, in a few rare but notable instances a cucurbit will revert to its ancestral genetics, over-producing cucurbitacin, a bitter compound used by wild cucurbits to repel insects. If you bite into a zuke, cuke, winter squash, or melon that tastes unbelievably bitter, spit it out. Toxic squash syndrome, the name for what happens if you swallow that bite, causes gastrointestinal mayhem and can result in serious complications from dehydration.
Though not a human health concern, allowing volunteers to reappear in the same place year after year permits the buildup of soil diseases: onion and garlic grown in the same spot will cultivate damaging fungal communities, an everlasting potato patch will soon be host to many debilitating pathogens, even tomatoes (who otherwise don’t nutritionally suffer from repeated plantings in the same soil) will attract a population of blight spores that will eventually be powerful enough to take out a whole patch in two days. Once in the soil, these diseases won’t leave in a gardener’s lifetime, hence the oft-repeated advice to rotate your garden vegetables.
With some discrimination, volunteers can be good for the garden (and gardener). Wind-dispersed seeds like lettuce will move about the garden on their own. If you’d like to rotate tomato or cucurbit volunteers, throw a few fruits here or there in late summer. Naturally occurring variations and adaptations make the going fun. If you aren’t a stickler for specific varieties, seeing and tasting what your volunteers become makes your garden unknown territory and you the explorer. This, along with a general appreciation for a garden’s will to live, is the point of volunteer gardening—to discover.