(Feathery-leafed yarrow seedlings)
The recent rain has woken up a bunch of seeds: some intentionally planted, some accidental but desired, and some not wanted.
A seed is an amazing thing. Within a tiny structure, there is the potential for a 6-foot tall sunflower or even a 60-foot tree. Seeds have the capacity to lie dormant for years until the right temperature and moisture conditions for germination come along. This is why mallow seedlings keep coming up on 20th Street every rainy season even though there hasn’t been a flowering mallow plant there for at least 2 years.
On the extreme end, lotus seeds collected in Manchuria from ancient lake beds were carbon-dated to 830 to 1250 years old. Some of those did sprout and produce flowers. Some vegetable seeds – cucumber and endive among them – may still sprout after 10 years. However, most seeds are viable – alive – for a few years at most.
The area in front of Sightglass Coffee, which in 2013 was underwatered and affected by foot traffic and construction, was replanted with native nursery plants in April of this year. Last month, wildflower seeds were sown to fill in bare areas. The recent rains have encouraged these seeds to germinate. Please don’t step on them!
The seed mix is the California Shady Wildflower Mix from Larner Seeds in Bolinas (www.larnerseeds.com) including the following native flowers: showy clarkia, Chinese houses, mountain phlox, mountain garland, five spot, tansy-leaf phacelia, bird’s eye gilia, tall and dwarf farewell-to-spring, and baby blue eyes (Clarkia amoena, Clarkia bottae, Clarkia unguiculata, Claytonia sibirica, Collinsia heterophylla, Gilia tricolor, Linanthus grandiflorus, Nemophila maculata, Nemophila menziesii, Phacelia bolanderii, Phacelia tanacetifolia).
Why plant from seed at all? Seedlings are vulnerable – their size makes them more easily damaged by careless feet, drought or frost. There’s also much less instant gratification factor. Putting plants in your garden would seem to make more sense. However, many plants available from nurseries are actually clones. (Insert bad sci-fi music here…) They are propagated from vegetative cuttings to create bigger plants on a faster timeline, and ensure a certain consistency. When you buy a flat of petunias from Home Depot, you can feel assured that they will all look and grow the same way in your garden.
Seeds, on the other hand, have some genetic diversity. To create a seed, pollen from a male flower part must fertilize an ovule in a female flower part, otherwise known as sexual reproduction. (*This is the PG-13 part!) Sexual reproduction results in genetic mixing, which is why you, your parents and your siblings don’t look exactly alike. Most plants have natural adaptations to prevent self-fertilization, to ensure genetic mixing with other plants of their species. Genetic mixing gives a more robust population, with better resistance to pest and disease, and some variation in size, shape and flower color.
Even better, plants grown from seed can generally produce more seed, which means free plants for the garden! By contrast, many nursery plants are not only clones, but also sterile hybrids (the parallel in the animal world would be the mule, which is the sterile offspring of a horse and a donkey). Most of the plants in the 20th Street Garden were originally grown from seed, even if they were installed as larger plants, so there is always sexual reproduction going on right there in the sidewalk. Who knew?
(A newer Bunny Tails grass (left) grown from a seed from the older plant (right))
Plants reseeding themselves on 20th Street include California Fuschia, Yarrow, Hedge Nettle and ornamental grasses. Not all of these seedlings will survive or grow in a desirable place, but we hope that enough will thrive and recharge the garden. The next time something unfamiliar sprouts in your garden, don’t just pull it up – wait a while and see what it turns out to be. You just might be pleasantly surprised.
Ellyn Shea is a gardener and garden consultant in San Francisco. Visit her at http://www.garden-guidance.com.