Germinating native flower seeds is more involved than the seed starting you may be used to, but it's not hard and it will scratch your gardening itch in winter. Wild Seed Project founder Heather McCargo joins me to explain how to start native flower seeds and the biodiversity benefits that it provides.
Heather grew up in Western Pennsylvania, outside of Pittsburgh. Her mother was a long-time organic gardener and naturalist, and Heather spent her time outdoors playing in the woods, fields, wetlands and streamsides. "I'm a child of nature," Heather says. She studied plant ecology at Hampshire College and got hands-on experience during several horticultural internships. She earned a master's from Conway School of Landscape Design, and during the 1990s, she was the head plant propagator at the Native Plant Trust's Garden in the Woods in Massachusetts.
Heather's experience also includes apprenticing under Jack Alexander, the propagator at the Arnold Arboretum of Harvard University in Boston. Jack taught Heather the many methods used to encourage seeds of hardy woody plants to germinate: filing the seed coat, touching the seed with a lit match, pouring boiling water on the seed, putting the seed in a refrigerator, etc. Though all these methods have some degree of effectiveness, Jack taught Heather in her first week that the simplest, most effective method is to simply throw the seeds outside.
Heather's goal is not to save native seeds but to sow native seeds and make more plants. From a little pot with 30 to 100 native seeds, you can plant out a population of natives. It's economical and rewarding, she says. "If you are always giving your neighbors giant zucchinis, instead you could be sharing those plants with your friends."
Heather started the Wild Seed Project because collecting, cleaning and processing wild seeds is time consuming and not economical. It requires a team of volunteers, though she says the work is, conveniently, a lot of fun.
You can read on for a brief recap of my conversation with Heather or see the show notes from the original airing for an unabridged write-up of our discussion.
Native Seeds and Plants Are Easier to Work With
When Heather shifted her focus to propagating native species, she aimed to mimic natural germination. She finds that sowing native seeds is easier than growing domesticated plants, which need compost, manure, and weeding. Native plants are adapted to local soils and don't require extra fertility.
Unlike vegetable seeds, native seeds shouldn't be started indoors or in a greenhouse. They germinate best when sown outdoors in late fall. Native plants vary in soil preferences - some like dry, sandy, or gravelly soil, others prefer hot clay or wet conditions - but they are generally less demanding.
Heather appreciates that native plants are resilient and vigorous. They don't need compost or manure for nutrients. For slow-growing natives in pots, she uses a weak seaweed solution as fertilizer. For established plants, she adds raked fall leaves to the beds, which provide all the supplemental nutrients the plants need.
How to Start Native Flower Seeds
Heather starts seeds outdoors in a compost-based potting soil, sowing one species per pot, leaving an 8th-inch of space between seeds. She then covers the seeds with coarse builder's sand in a layer that is as thick as the seeds are large. So an acorn is covered by an inch of sand, and a sunflower seed is covered by a quarter-inch. Tiny, dust-like seeds that are traditionally sown directly on the soil surface get just a dusting of sand.
The coarse sand protects the seeds from bouncing out of the pot in the rain. A storm window can be placed over the pots to protect the seeds from torrential rains, but the windows need to be removed as soon as the seeds germinate.
Because the pots are outdoors, fungus gnats, damping off, mold, mildew and other challenges that occur indoors are not an issue. Heather never worries about the seeds rotting in wet weather either. The seeds can take it. However, being outdoors means the pots need protection from squirrels and chipmunks. so place wire mesh over the pots.
Place the pots in a shady area on a flat surface, like a stone terrace on the north side of your house. A level surface ensures the seeds don't shift to one side. Shade is crucial to prevent seedlings from drying out on hot spring days. Once the seedlings are established, sun-loving species can be moved to a sunnier spot.
Over the winter, the seeds may experience freezing rain, snow and sleet. That's great because the seeds need fluctuation in temperatures to germinate. Freezing and thawing breaks apart the seed coat. If the seeds prematurely germinate during a warm spell, the plants are not doomed. The seeds know what they are doing, and the seedlings will stay tiny until spring comes.
