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 served as the executive director of the nonprofit Wild Seed Project from 2014 to 2021. She is also the lead author of the first Wild Seed Project guide, Native Trees for Northeast Landscapes, wrote the Maine Department of Transportation native plants handbook and was the founding editor of Wild Seed magazine.
Heather McCargo is the founder and former executive director of the Wild Seed Project and the founding editor of Wild Seed Magazine. (Photo Courtesy of Heather McCargo)
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.
Blue vervain seeds. (Photo Courtesy of Heather McCargo)
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.
Wild geranium (Geranium maculatum) seedheads. (Photo Courtesy of Heather McCargo)
Sow Native Flower Seeds in Pots for Greater Success
Heather advises New England gardeners to sow seeds over the winter holidays, once other outdoor tasks are done. In warmer climates, the timing may differ, but the approach is the same: sow seeds in pots rather than scattering them outdoors. This significantly boosts the chances of successful germination and growth.
“Everybody wants to just toss the seeds out into the landscape, but what that doesn’t take into account is the dangerous life of a seed,” Heather says. “Most seeds that a wild plant produces don’t land in a place where they germinate and become an adult plant. A typical plant can produce millions of seeds over its lifetime, and those aren’t all becoming new plants. They get eaten by birds or mice. They become part of the food chain.”
When sowed in small pots outdoors, however, most native seeds will successfully germinate. Clay pots are ideal due to their porosity, though recycled plastic pots work too, as long as they don’t retain too much water. Fiber pots are not recommended, as they slow down plant growth.
When sowed in small pots outdoors, most native seeds will successfully germinate. Wire mesh will protect the seeds from hungry critters. (Photo Courtesy of Heather McCargo)
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.
Beardtongue (Penstemon) seedheads and seeds. (Photo Courtesy of Heather McCargo)
Potting Up & Planting Native Flowers
In summer, Heather moves plants from their small starter pots into larger ones. While plants can be divided, it disrupts the roots and slows growth. If overcrowded, divide the pot into quarters and transplant each into a larger pot.
Water the pots regularly to prevent them from drying out, checking moisture three times a week and removing any weeds. Once the summer heat subsides, usually in September, transplant the seedlings into the landscape.
After the seeds sprout and fill out their original pots in spring, pot up the plants so they have room to grow in summer. (Photo Courtesy of Heather McCargo)
I hope you enjoyed my conversation with Heather McCargo on starting native flower seeds. If you haven’t listened yet, you can do so now by scrolling to the top of the page and clicking the Play icon in the green bar under the page title.
Have you started native flower seeds? Let us know about your experience in the comments below.
Links & Resources
Some product links in this guide are affiliate links. See full disclosure below.
Episode 015: Life Lessons on Gardening and Design with Margaret Roach
Episode 037: Starting Seeds Indoors: The Non-Negotiables for Success, Pt. 1
Episode 072: Creating an Eco-friendly Garden & Landscape: 7 Key Tenets
Episode 094: How to Start and Care for Seedlings Indoors: My Steps for Success
Episode 103: How to Create a Backyard Meadow: Simple Steps for Success No Matter the Space
Episode 130: Winter Sowing: A Simple Way To Successfully Start Seeds Outdoors
Episode 180: Growing and Using Ornamental Grasses in the Landscape, with Brie Arthur
Episode 197: The Many Benefits of Building a Naturalistic Garden, with Kelly Norris
Episode 201: Understanding Regenerative Agriculture and Permaculture, with Dr. Jake Mowrer
Episode 234: Converting Lawn into Meadow
Episode 235: The Easiest Way to Start and Grow Native Seeds in Winter: No Special Equipment Required
joegardener blog: The Best Soil Temperature for Seed Germination
joegardenerTV YouTube: How to Create a Wildlife-Friendly Habitat in Your Garden or Landscape
joegardenerTV YouTube: Seed Germination – Easy Tricks for More Success
joegardenerTV YouTube: How to Know if Seeds Are Still Good
joegardenerTV YouTube: How to Plant Seeds for Indoor Seed-Starting
joegardener Online Gardening Academy™: Popular courses on gardening fundamentals; managing pests, diseases & weeds; seed starting and more.
joegardener Online Gardening Academy Organic Vegetable Gardening: My new premium online course. The course is designed to be a comprehensive guide to starting, growing, nurturing and harvesting your favorite vegetables, no matter what you love to eat, no matter where you live, no matter your level of gardening experience.
joegardener Online Gardening Academy Master Seed Starting: Everything you need to know to start your own plants from seed — indoors and out.
joegardener Online Gardening Academy Beginning Gardener Fundamentals: Essential principles to know to create a thriving garden.
joegardener Online Gardening Academy Growing Epic Tomatoes: Learn how to grow epic tomatoes with Joe Lamp’l and Craig LeHoullier.
joegardener Online Gardening Academy Master Pests, Diseases & Weeds: Learn the proactive steps to take to manage pests, diseases and weeds for a more successful garden with a lot less frustration. Just $47 for lifetime access!
joegardener Online Gardening Academy Perfect Soil Recipe Master Class: Learn how to create the perfect soil environment for thriving plants.
GGW Episode 418: Garden with Margaret Roach
GGW Episode 1011: Creating a Meadow Garden, Anywhere Around Your Yard
“Native Trees for Northeast Landscapes: A Wild Seed Project Guide” by Heather McCargo and Anna Fialkoff
“Native Plants for Roadside Restoration” by Heather McCargo
Arnold Arboretum of Harvard University
Milorganite® – Our podcast episode sponsor and Brand Partner of joegardener.com
Disclosure: Some product links in this guide are affiliate links, which means we get a commission if you purchase. However, none of the prices of these resources have been increased to compensate us, and compensation is not an influencing factor on their inclusion here. The selection of all items featured in this post and podcast was based solely on merit and in no way influenced by any affiliate or financial incentive, or contractual relationship. At the time of this writing, Joe Lamp’l has professional relationships with the following companies who may have products included in this post and podcast: Corona Tools, Milorganite, Soil3, Territorial Seed Company, Earth’s Ally, Proven Winners ColorChoice, Farmer’s Defense, Heirloom Roses and Dramm. These companies are either Brand Partners of joegardener.com and/or advertise on our website. However, we receive no additional compensation from the sales or promotion of their product through this guide. The inclusion of any products mentioned within this post is entirely independent and exclusive of any relationship.
