7 Ways to Encourage Your Favorite Plants to Self-Sow
Self-sowing plants are a boon for us gardeners! They reseed themselves so we don’t have to plant them. Some sprout readily with little help, while others benefit from some care to grow their best. Use these seven methods to encourage annuals, perennials, and shrubs to sprout new seedlings throughout your garden.
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I love reseeding species! What’s not to love about them? They grow well during the growing season, producing dozens of blossoms, leaves, and seed pods. Their seeds fall to the ground where they germinate or hide out until their preferred weather arrives. They give you free plants with little effort, turning your bare garden into a lush oasis.
Native plants are the best self-sowing species, as they naturally spread themselves without human intervention in their habitats. Plant them in your garden, and they’ll sow themselves in new locations each year. They may even spread seeds to local wild spaces that need more native species!
Heirloom varieties are another ideal option. They, like native plants, grow seedlings with similar characteristics as themselves. If you plant an heirloom with red flowers, it’ll most likely grow seedlings that also have red flowers. Hybrid plants, however, aren’t genetically stable; they are more likely to sow new plants with wildly different traits. You may let them self-sow as a fun experiment to see what kind of new plants grow!
No matter which species you want to self-sow, these seven methods will guide you through the process. Let’s dive in and encourage our favorite flowers to spread!
Grow Self-Sowing Species
Whether a plant self-sows depends on a few conditions. It must adapt to your local climate, soil, and garden. Mild-climate gardeners with little winter frost should try planting tropical or subtropical species that don’t need winter chill to sprout. These perform best in warm zones since they sprout with warmth and moisture.
Cold-climate gardeners with recurring winter frosts should try reseeding species that require cold stratification. Cold stratification is a term for the frosty period some seeds need to germinate in spring. They sense freezing temperatures and the warmth that follows in spring, which signals that it’s time to sprout.
Here’s a chart that shows some of the best species to try first. Use it as a starting point, and experiment with other rare plants to find your favorites.
| Common Name | Scientific Name | Requires Cold Stratification? |
| Purple Coneflower | Echinacea purpurea | No, but it helps germination rates |
| Showy Milkweed | Asclepias speciosa | Yes |
| Black-Eyed Susan | Rudbeckia hirta | Yes |
| Poached Egg Plant | Limnanthes douglasii | No |
| Garden Balsam | Impatiens balsamina | No |
| Feverfew | Tanacetum parthenium | No |
| Pansy | Viola x wittrockiana | No |
| Spotted Geranium | Geranium maculatum | Yes |
| Goldenrod | Solidago spp. | Yes |
Stop Deadheading Spent Flowers
Plants form seeds in their flowers. Pollen falls into the stigma, the female sex organ, where it fertilizes egg cells within the flower called ovules. After fertilization, these ovules develop into embryos called seeds. These are what we use to propagate our favorite species.
This unique process only occurs if flowers persist after they fade. When you deadhead spent blossoms to encourage more blooms, you halt the fertilization process. They push more blossoms out as they attempt to make up for their lost seeds.
If you want reseeding plants to sow themselves, you must leave the flowers to wither, brown, and fall to the ground. This is true for annuals, perennials, shrubs, and trees. Leaving the blossoms also allows more insects and pollinators to visit them, increasing their chances of successful pollination and fertilization.
Deadheading is generally okay early in the growing season since there’s still ample time for your plants to form more flowers. Cease deadheading by late summer or early fall so they can create embryos before the first frosts arrive.
Feed The Soil
Rich, porous, and absorbent soil is perfect for seed starting. When it’s high quality with small particles, it’s conducive to growing new seedlings. Seeds fall into it and find the moisture, nutrients, and air they need. You’ll create the perfect home ahead of time so these new baby plants thrive from the moment they germinate.
Feeding the soil is an excellent way to maintain high-quality dirt. Add amendments like compost, leaf mold, or worm castings to help the soil structure while you feed it. Organic particles like these persist and create air spaces underground. Plant roots grow into these spaces where they access air and moisture as they need to.
Sometimes garden beds lack the nutrients that reseeding species need. A soil test kit is a great way to see which ones your garden has and which ones it’s missing. Then, you can add the correct amounts of specific amendments or fertilizers you need while avoiding oversaturation of the site. Compost and leaf mold add nutrients and structure to gardens, although they take longer to leach into the ground than fertilizers.
Don’t Add Too Much Mulch
Mulch is amazing, but too much can prevent your self-sowing plants from sprouting! You’ll want to add the perfect amount of improvements to boost their performance while ensuring they have access to rich soil.
Some amendments, like a thin layer of compost or leaf mold, allow seeds to grow despite coverings. Seedlings germinate in the nutrient-rich and porous materials, sending roots downward into the soil beneath the mulch. Other mulches, like wood chips or synthetic types, hinder seed germination by preventing them from accessing soil particles.
For best results, use soil amendments that seeds can germinate in. I can’t stress enough how good compost and leaf mold are for the garden! Other organic types are okay so long as they’re in a thin layer. Seeds will fall through the few pieces and germinate below the cover.
Concerns about overfertilizing sites with organic amendments are valid. Too much of the stuff can cause nutrient imbalances that harm sensitive roots and germinating seedlings. Use plant-based composts or leaf mold for best results, as these lack harmful manure side effects and work well in large quantities.
Help Plants Self-Sow
If germination rates are low this season, consider lending your plants a helping hand. This simple trick boosts seed starting success rates and it’s relatively easy to do. Simply gather the seed heads when they are ripe, and scatter them throughout your garden. Tamp them lightly with your foot in in-ground beds, or with your hand in raised beds.
This action gives you some control over where the garden species self-sow. Wherever you scatter the seed heads, new seedlings will likely sprout in fall or spring. Try this with any plant that germinates on the soil’s surface.
This method works well for vegetable crops and ornamentals. Try it with onions, Swiss chard, and spinach. If you have a few seedlings past the point of harvesting, let them flower and set seeds for free veggies throughout the year.
Some seeds need soil above them to germinate, and they thrive below cover. Let them fall to the ground and place mulch and amendments above them—you’ll create their ideal home and help them sprout.
Sow Seeds Yourself
While self-sowing plants usually don’t need help, you can take the initiative by boosting their population levels. Saving a few seeds gives you a backup in case seedlings don’t sprout when you expect them to.
Start by collecting seeds from spent blossoms when they’re ripe. Ripe ones are hard but slightly squishy, and they typically fall out of the heads when they’re ready. Some species, like garden balsam, have explosive seed pods that burst when you touch them! Take care during collection to ensure you find as many as possible.
Let the seeds dry, then place them in an airtight container or an envelope. Store the containers in a cool, dark location until you’re ready to plant them. Most will last for a year or longer with proper storage, meaning you can save some in the fall for new plants in spring.
Watch for Seedlings
Weeds and garden plants look similar when they’re young, and it’s easy to confuse the two! I found this the hard way one year when I pulled all my catnip seedlings thinking they were purple dead nettle! It’s best to let weeds grow a bit instead so you can properly identify them. This is especially true if you’re trying to foster reseeding plants.
Weed removal is important, though, and it helps germinating seedlings have access to all the sunlight, soil, and water they need. Find a sweet spot when the weeds are still young but identifiable, and remove them before they grow flowers and seeds.
Weeds make excellent mulch if they don’t have seeds or rooting stems on them. Pick them, separate their roots, and throw them back on the ground (as long as they aren’t an invasive species). They’ll decay and help your preferred garden plants thrive.
