Seed-planting guide for natural gardens

On episode 5, season 4 of the Cottage Life Podcast, gardening expert Lorraine Johnson shares the benefits of native plants for your cottage garden. Listen to the show below, and then the rest of the season here.

Think of it as new plants for free—an endless supply at the drop of a seed. Propagating your own plants from seeds you’ve collected around your cottage saves you money, helps preserve the rich community of native species in your area, and provides an incomparable measure of satisfaction and accomplishment. Each self-raised plant feels like the most miraculous personal success—a green-thumb pat on the back. Indeed, it’s easy to feel kind of smug when all those seedlings are lined up in their pots ready to be launched into full adulthood in your cottage garden, and they’re ready because of you.

As with any aspect of native plant gardening, the key to propagating seeds from the wild is to mimic their natural process: They ripen on the plant, drop, and grow. Okay, it’s a little more complicated than that, but, essentially, you can think of it as “ready, set, grow.”

Ready, set…

During rambles in the woods or meadows around your cottage, note the wild plants you’d like to grow in your garden. Observe their flowering times (e.g. bloodroot in spring, meadow rue in summer, asters in fall) and mark their locations with a stick or even a twist-tie wrapped around the stem so you can find them easily and return for their seed.

After flowering, plants begin to form their seeds—in seedheads, pods, capsules, or fruit—and many are ready to harvest approximately one month later. Check for these clues to ripeness: When pods or capsules, say of butterfly milkweed or columbine, start to turn yellowish-brown, look dry, and begin to crack or split open, the seeds are probably ready. Simply squeeze the pod or break off and shake the capsule, then put the seeds into an envelope or paper bag (coin collection envelopes or glassine stamp envelopes, available at stationery stores, work well (not plastic containers such as baggies or film canisters because they’re airtight, and seeds need to breathe).

For species with fluffy seedheads, such as asters, ironweed, and goldenrod, just cut off the heads when they look dry and shake or rub them inside a paper bag; seeds by the hundreds will collect in the bottom. Make sure to label the envelopes or bags right away, particularly if you’re gathering a lot of different species at one time.

Other plants, such as wild geranium, large-flowered bellwort, and jewelweed, require a bit of cunning, as these species actually eject their seeds. (If you listen carefully, you’ll hear a stand of jewelweed “popping” their ripe seed.) To catch them, you’ll have to fasten a paper bag loosely around the seed pods [heads] when they start to ripe (look for a change in colour) to catch these dramatic jumpers.

Some spring-blooming woodland plants, such as mayapple, false Solomon’s seal, and Jack-in-the-pulpit, have their seeds encased in fleshy fruits, which change colour and become soft when ripe. Pluck the fruit from a species and soak it in a container of water for a day or two, after which you should discard any that rise to the surface. (These floaters won’t germinate.) Put the rest of the fruit in a sieve and gently mash, releasing the seed from the flesh. It’s important that seeds from fleshy fruits don’t dry out, so plant them immediately. Most other species, though, can be stored until you’re ready to plant.

Although you may be tempted to collect all the available seeds, resist the temptation. As Deborah Dale, president of the North American Native Plant Society (NANPS), says, “We recommend you collect no more than 10 per cent of the seeds from a particular plant; leave the rest for natural dispersal. And, of course, don’t take seeds from endangered or rare plants, or plants with very limited populations.”

…Grow

Once you’ve got a collection of labelled seeds, it’s a good idea to let them dry in the open air for a few days to lower their moisture content so they’re less vulnerable to disease, then clean the chaff for easier planting later. Then consider your storage options. For most native species, it’s safe to store seeds for a winter; if you end up stashing them for a year or more, you’ll have lower rates of germination, but some of the seeds will still be viable. (The exceptions to this rule are seeds in fleshy fruits—they do not store well and should be planted soon after collection and not allowed to dry out.) If you choose to store seeds over winter or longer, they’ll need to go through either a cold period or a cold moist period that mimics our natural winter before they can germinate. This process is called cold or cold moist stratification and involves storing seeds in the fridge (in a sealed baggie filled with damp vermiculite) for approximately six to eight weeks before you plan to pot them up for germination.

A more convenient strategy for cottagers is simply to pot the seeds in autumn and leave them outside all winter. If you go this route, use sterilized potting soil, which can be purchased from any nursery; soil from the garden will have lots of weed and other seeds, which, when they sprout, will make it hard for you to identify the desired species. To plant the seeds, scatter them lightly onto the surface of the potting mix and finger-press them down. Cover with a light dusting of potting mix and then sprinkle some water on top, gently. A good general practice is to plant seeds to the same depth as their thickness.

You’ll have to cover them with fine wire mesh or other protection to keep rodents and small animals from digging them up, but other than that, there’s not much else you need to do. (Mist the soil after planting, but no other watering is necessary.) The seeds will freeze and thaw and get wet from rain and snow—all those things that happen to seeds in the wild—and then they’ll germinate in spring, when their internal clocks tell them it’s time. Some species, such as trillium, Solomon’s seal, false Solomon’s seal, and bellword, have to go through two winters before they germinate, but they’re the exception, not the rule.

Native plant gardener Jim Hodgins, the editor of Wildflower magazine, suggests a slightly different method, which has the advantage of not requiring pots but can still be done in fall: “In a semi-shaded area construct a nursery bed frame using logs, stones or bricks to delineate the bed. Fill with local soil. Plant collected seeds in a straight line, labelling each row with the name of the species and the date planted. Sprinkle a light covering of soil and then cover the bed with fine wire mesh to deter critters. Water gently until the soil is thoroughly moist.”

Once germination occurs, you should keep the soil moist and protected from full sun and strong winds. It’s best to wait until the plant looks vigorous and well established in its growth (at least a couple of leaves and a strong stem) before planting it out in the garden. For some fast-growing species, such as black-eyed Susans, the seedlings will probably be ready for transplanting by mid-summer. If you’re in doubt, keep your seedlings in their pots or the nursery bed until late summer or early fall, then plant them in the garden. Whenever you transplant, though, it’s important to keep the young plants well watered. You may not see blooms the first season but by the following summer, most native species will reward you with colourful flowers and then go to seed. By then, you’ll be a propagation expert, reading to begin your seed-starting adventures all over again.

Seed styles

Capsules

Eastern columbine (Aquilegia canadensis)
Turtlehead (Chelone glabra)
Beardtongue (Penstemon spp.)
Tall bellflower (Campanula americana)
Flowering spurge (Euphorbia corollata)

Pods

Butterfly Milkweed (Asclepias tuberosa)
Swamp Milkweed (Asclepias incarnata)
Spring Beauty (Claytonia virginica)
Fireweed (Epilobium angustifolium)

Fluffy seedheads

Plantainleaf pussytoes (Antannaria plantaginifolia)
Asters (Aster spp.)
Spotted Joe-pye weed (Eupatorium maculatum)
Boneset (Eupatorium perfoliatum)
Rough blazing star (Liatris aspera)
Goldenrods (Solidago spp)

Fruits/berries

Red baneberry (Actaea rubra)
Jack-in-the-pulpit (Arisaema triphyllum)
False Solomon’s seal (Smilacina racemosa)
Solomon’s seal (Polygonatum biflorum)
Wild ginger (Asarum canadense)

Seed maturation times

Early summer

Plantainleaf pussytoes (Antannaria plantaginifolia)
Eastern columbine (Aquilegia canadensis)
Wild geranium (Geranium maculatum)
Bloodroot (Sanguinaria canadensis)
Barren strawberry (Waldsteinia fragarioides)

Mid-summer

Red baneberry (Actaea rubra)
Beardtongue (Penstemon spp.)
Tall meadowrue (Thalictrum polygamum)
Foamflower (Tiarella cordifolia)
Bellwort (Uvularia grandiflora)

Late summer

Swamp milkweed (Asclepias incarnata)
Butterfly milkweed (Asclepias tuberosa)
Fireweed (Epilobium angustifolium)
Wild bergamot (Monarda fistulosa)

Fall

Jack-in-the-pulpit (Arisaema triphyllum)
Asters (Aster spp.)
Turtlehead (Chelone glabra)
Spotted Joe-pye weed (Eupatorium maculatum)

Seeds that should be planted as soon as they’re ripe

Wild ginger (Asarum canadense)
Hepatica (Hepatica spp)
Bloodroot (Sanguinaria Canadensis)
Trillium (Trillium grandiflorum)
Mayapple (Podophyllum peltatum)
Bellwort (Uvularia grandiflora)
Baneberry (Actaea spp.)
Jack-in-the-pulpit (Arisaema triphyllum)
False Solomon’s seal (Smilacina racemosa)
Solomon’s seal (Polygonatum biflorum)

Lorraine Johnson is an avid native species gardener and author of nine? books on the subject. Her latest, The Gardener’s Manifesto, is now out in paperback.

This essay appeared in the October 2003 issue of Cottage Life as the last part of a four-part series. You can find the rest here: Part 1: Let native plants guide your gardening, Part 2: Understanding soil and landscape quality when gardening, Part 3: Overcoming your garden’s critters and septic beds.

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