Black Eyed Susan seeds are small, dark, narrow structures roughly the size of a grain of rice or slightly smaller. Each seed is typically about 1.5 to 2 millimeters long, dark brown to nearly black, and has a slightly angular or ridged shape with four subtle sides. They develop inside the prominent dark central cone of the flower head, packed tightly together in a spiral pattern, and they look nothing like the bright yellow blooms they eventually produce.
A Closer Look at the Seeds
The seeds of Rudbeckia hirta, the most common Black Eyed Susan species grown in gardens, are easy to overlook because of their size. Hold one between your fingertips and you’ll notice it’s elongated, somewhat club-shaped, and slightly wider at one end than the other. The surface has a faint texture to it, with fine lengthwise ridges running along the body of the seed. The color ranges from medium brown to very dark brown, sometimes appearing almost black when fully mature. Lighter brown or tan seeds pulled from a head that hasn’t fully dried tend to be less mature and may not germinate as reliably.
Unlike seeds from sunflowers (a close relative in the same plant family), Black Eyed Susan seeds have no obvious shell to crack open and no fluffy tuft of hairs to help them drift on the wind. They’re dry, hard little slivers. Botanically, each one is an achene, meaning the “seed” is actually a small dry fruit with the true seed enclosed inside a thin outer wall. For practical gardening purposes this distinction doesn’t matter much, but it explains why the seeds feel firm rather than soft when you roll them between your fingers.
What the Seed Head Looks Like Before You Harvest
Knowing what the seeds look like in isolation is useful, but most people first encounter them still sitting in the dried flower head. After the yellow petals drop in late summer or early fall, the central cone remains on the stem. That cone, which was dark brown or nearly black even when the flower was in bloom, gradually dries out and turns a lighter grayish-brown. The cone’s surface is covered in tiny, tightly packed scales, each one sheltering a single seed underneath.
When the seed head is fully ripe, it feels dry and somewhat brittle. If you press on it or roll it between your palms, the individual scales separate and the seeds start falling out. An unripe head will feel firmer and more resistant to crumbling. You can test readiness by bending the stem: if it snaps cleanly and the head crumbles easily, the seeds are ready. If the stem is still flexible and green, give it more time.
A single mature flower head can contain dozens of seeds, sometimes well over a hundred in larger varieties. The seeds are mixed in with the small papery scales (chaff) from the cone, so what falls out looks like a jumble of dark slivers and lighter bits of plant debris. Separating the two is part of the harvesting process.
How to Tell Seeds Apart from Chaff
This is the question that trips up most first-time seed savers. When you crumble a dried Black Eyed Susan seed head, you get a pile of material that all looks vaguely similar at first glance. The seeds and the chaff are roughly the same size, and both are brown. Here’s how to sort them out:
- Weight: Seeds are denser than chaff. If you gently blow across a flat surface covered with the mixture, the lighter chaff will drift away while the heavier seeds stay put.
- Shape: Seeds are narrow, elongated, and slightly angular. Chaff pieces tend to be flatter, wider, and irregularly shaped, more like tiny flakes or scales.
- Color: Mature seeds are consistently dark brown to black. Chaff is usually lighter, ranging from tan to medium brown, sometimes with a papery, translucent quality.
- Firmness: A viable seed feels solid if you press it between your fingernails. Chaff crumbles or collapses easily.
Perfect separation isn’t necessary for planting. A little chaff mixed in with your seeds won’t hurt anything when you scatter them. If you’re storing seeds for later, though, removing most of the chaff helps reduce moisture and the chance of mold.
When and How to Collect Seeds
Timing matters more than technique. Black Eyed Susans bloom from early summer into fall depending on your climate, and seeds mature a few weeks after the petals fall. In most regions, seed collection happens from late August through October. The key indicator is that the seed heads have turned fully dry and brown on the plant. Heads that still have green at the base of the cone aren’t ready.
The simplest collection method is to snap or cut the entire dried seed head off the stem and drop it into a paper bag. Avoid plastic bags, which trap moisture and invite mold. Once you have a bag full of heads, you can crush them by hand or shake the bag vigorously to dislodge the seeds. Then pour the contents onto a plate, pick out any large stem pieces, and use the blowing technique described above to winnow out most of the chaff.
If you’d rather let the plant do the work, you can also tie a small mesh bag or piece of cheesecloth loosely around a few seed heads while they’re still on the plant. As the head dries and seeds loosen naturally, they’ll fall into the bag instead of dropping to the ground. This method is especially useful if birds are eating your seeds before you can get to them. Goldfinches are particularly fond of Rudbeckia seeds and will strip a seed head bare in a day or two if given the chance.
Checking Whether Seeds Are Viable
Not every seed you collect will be capable of growing into a plant. Some are hollow, undeveloped, or damaged. A few quick checks can help you estimate how good your seed batch is before you invest time planting.
The squeeze test is the easiest. Pick up individual seeds and press them gently between your thumbnail and fingertip. A viable seed resists the pressure and feels firm inside. An empty or dead seed collapses easily, feeling hollow or papery. In a typical harvest, expect a meaningful percentage of duds mixed in with the good ones. This is normal for wildflower seeds and is one reason gardeners tend to sow them generously rather than placing each one precisely.
You can also try a float test. Drop a small handful of seeds into a cup of water and wait five to ten minutes. Seeds that sink are generally denser and more likely to be viable. Seeds that float are often empty. This test isn’t perfect since small air pockets can keep a good seed afloat, but it’s a reasonable rough filter. Dry the seeds thoroughly on a paper towel after testing if you plan to store them rather than plant immediately.
Freshly collected seeds from a healthy plant typically have germination rates somewhere in the range of 50 to 70 percent, depending on growing conditions that season and how well the seeds were stored. That rate drops over time, so seeds planted within a year or two of collection tend to perform best.
Seeds from Different Rudbeckia Species
The name “Black Eyed Susan” gets used loosely, and several related species share it. Rudbeckia hirta is the most common, but Rudbeckia fulgida (orange coneflower) and Rudbeckia triloba (thin-leaved coneflower) also go by the same common name in different regions. Their seeds are similar enough to cause confusion but different enough to notice if you’re comparing them side by side.
Rudbeckia fulgida seeds, particularly from the popular ‘Goldsturm’ cultivar, tend to be slightly smaller than Rudbeckia hirta seeds and are often a bit more uniformly dark. Rudbeckia triloba produces noticeably smaller seeds overall, reflecting its smaller flower heads. Rudbeckia laciniata, the cutleaf coneflower, has seeds that are a bit larger and sometimes lighter in color than the typical Black Eyed Susan.
For most gardeners this distinction doesn’t matter much unless you’re trying to identify a mystery Rudbeckia by its seeds alone. In that case, seed size and the shape of the dried seed head together give you a better clue than seed appearance alone. Rudbeckia hirta seed heads are roughly hemispherical to slightly conical and about 1 to 1.5 centimeters across. Rudbeckia laciniata heads are noticeably larger and more columnar.
Storing Seeds for Future Planting
Black Eyed Susan seeds store well if you keep them cool and dry. After cleaning off most of the chaff, spread the seeds in a single layer on a paper towel or plate and let them air-dry for a few days in a spot with good air circulation and no direct sunlight. Once they feel completely dry, transfer them to a paper envelope or small glass jar.
Label the container with the species name and collection date. This sounds obvious, but a year from now, a jar of tiny dark seeds with no label is going to be impossible to identify. Store the container in a cool, dark place. A refrigerator works well. The freezer is fine too, as long as the seeds were thoroughly dried first; moisture inside frozen seeds expands and kills the embryo.
Under good storage conditions, Black Eyed Susan seeds remain viable for two to three years, sometimes longer. Germination rates decline gradually, so if you’re planting seeds that are a couple of years old, sow a little more thickly to compensate. Seeds older than four or five years may still produce a few plants, but the germination rate will be low enough that you’re better off collecting fresh seed.
Why Seeds Look Different from What You Expected
If you bought a packet of Black Eyed Susan seeds from a garden center, the seeds inside may look slightly different from what you’d harvest from your own plants. Commercial seed is often cleaned more thoroughly, so there’s less chaff mixed in. Some commercial seed is also coated with a thin layer of clay or fungicide, which can make the seeds appear lighter in color, slightly larger, or more uniformly shaped than raw seed. A bright blue or pink coating is a fungicide treatment and is common on commercially sold flower seed. The coating doesn’t change what’s inside.
Hybrid cultivars can also produce seeds that look a bit different from the straight species. ‘Cherokee Sunset,’ ‘Denver Daisy,’ and other named varieties have been bred for specific flower traits, and their seeds may be slightly larger or smaller than typical Rudbeckia hirta seed. The basic shape and color remain recognizable, though. If it’s a small, dark, angular sliver, you’re looking at a Black Eyed Susan seed regardless of the cultivar.
One more source of confusion: seeds from plants in the broader Asteraceae family, which includes coneflowers, daisies, and asters, share a general family resemblance. Echinacea seeds (purple coneflower) are a common mix-up. They’re similar in size and shape to Rudbeckia seeds but tend to be slightly lighter in color, more angular, and often have a sharper point at one end. If you’ve been growing both plants in the same bed and lost track of which seed head came from which plant, comparing the size and shape of the dried cone is a more reliable identification method than staring at the individual seeds.
Planting Seeds Directly Outdoors
Black Eyed Susans are one of the easier wildflowers to grow from seed, partly because the seeds aren’t picky about conditions. They germinate best with a period of cold stratification, which is a fancy way of saying they like to experience winter before sprouting. If you sow seeds in the fall, the natural freeze-thaw cycles of winter take care of this. Scatter the seeds on the soil surface, press them lightly into contact with the ground, and leave them uncovered or barely covered. The seeds need light to germinate, so burying them even a centimeter deep can reduce your success rate significantly.
Spring sowing works too, but you may want to simulate winter first by mixing the seeds with a small amount of damp sand, sealing the mixture in a plastic bag, and refrigerating it for four to six weeks before planting. This cold-moist treatment breaks seed dormancy and improves germination. Without it, spring-sown seeds may still come up, but less reliably and over a longer, more erratic timeframe.
Expect germination in roughly one to three weeks once soil temperatures are consistently warm, around 15 to 21°C (60 to 70°F). The first leaves you’ll see are a pair of small, rounded cotyledons that look nothing like the rough, lance-shaped leaves of the adult plant. Don’t mistake the seedlings for weeds and pull them. By the time the second set of true leaves appears, the characteristic leaf shape becomes recognizable.
Self-Seeding and Volunteer Plants
Once established, Black Eyed Susans are prolific self-seeders. Each plant produces hundreds of seeds across multiple flower heads, and those seeds don’t need any help from you to find the ground. In a garden setting, this can be either a gift or a headache depending on your tolerance for plants that colonize freely.
Rudbeckia hirta is technically a short-lived perennial or biennial, meaning individual plants typically live two to three years. The species persists in a garden not because the same plants keep returning, but because new seedlings constantly replace the ones that die off. If you deadhead spent flowers before the seeds mature, you can slow this cycle considerably. If you want more plants, leave a few seed heads standing through winter and you’ll likely have dozens of volunteers the following spring.
The volunteer seedlings from hybrid cultivars won’t necessarily look like their parent. If you grew ‘Cherokee Sunset’ with its russet and bronze tones, the seedlings may revert toward the classic yellow-petaled, dark-centered look of the wild species. Seed saved from hybrids is genetically variable in a way that seed from straight species is not. For consistent results with named cultivars, purchasing fresh seed or dividing established clumps of perennial Rudbeckia species is more reliable than saving your own.