While most gardeners prefer to grow perennials from established plants in containers or as divisions, transplants, or bare root, growing many perennials successfully from seed is possible.
Many gardeners prefer perennials grown from established plants because when propagated vegetatively by division or other methods using the plant's vegetative parts (roots, stems, and/or leaves), they result in propagules identical to the parent plant. Perennials grown from seed will be similar to the parent plant but may differ in flower color, leaf pattern, size, habit, or other ways. Sometimes, this variation is not a problem - sometimes, it is even welcome. However, if you want to maintain a specific trait, like flower color, the variation from seed propagation is problematic.
Growing perennials from seed offers gardeners a cost-effective and rewarding way to fill their gardens with a diverse range of plants. While it requires patience and some basic knowledge, the process can be fulfilling. Here’s a detailed guide on how to successfully grow perennials from seed.
Seed Collection | Breaking Dormancy | Set-up | Easy Perennials to Grow From Seed | Germination of Specific Species | Sources | More Information
Seed Collection
Harvesting Seed
The late growing season is a good time to collect seeds from many perennials, but the precise timing will vary from species to species. Collect seed after it’s been allowed to reach full maturity. Just as flowers and fruit form at different times on the plant, seeds will mature at different rates. Collect individual pods or fruit that contain seeds throughout the growing season as they mature. When seeds are in dry husks or pods, leave them on the plant to dry as long as possible. If conditions become too wet or cold, entire plants can be harvested and hung to allow seeds to fully mature.
Harvest seed from the best performing plants in the garden. Save seeds from the plants with the best color, most desirable form or growth habit, and exhibit the fewest disease issues. This will ensure that future generations will perform well in your garden.
Processing and Cleaning Seed
Cleaning methods for seeds will vary from species to species depending on whether the seeds are in dry or fleshy fruit. Most perennials produce seeds in dry fruit or pods. The mature seed can be separated from the chaff in several ways. Threshing, smashing, and shelling can be used to physically separate the seed from the flower head, husk, or pod. For some seeds, simply shaking the seed over a container or paper bag will release the seed. Screening with colanders, sieves, or other screen materials can also be used to separate the seeds from the chaff. Winnowing separates heavier seeds from lightweight chaff by using a fan to blow away the chaff. Seed lots are often screened or winnowed several times to remove as much chaff as possible.
Storing Seed
Seed that will not be sown immediately must be stored properly to maintain viability and good germination at planting time. Seeds should be kept dry and cool. A sealed glass jar can keep excess moisture out and protect seeds from pests like mice or insects. Store jars in a cool, dry location such as a cool closet, root cellar, or refrigerator. Test the germination rate on the seeds about one month prior to planting.
Ensuring the seed is dry after cleaning and processing is the most important step to successfully storing seed. Place seed in labeled envelopes. In a separate envelope, place an equal amount of silica gel. Place both envelopes into a clean glass jar and seal shut. After one to two weeks, the seed should be sufficiently dry for storage. Remove the silica gel and return the envelope to the glass jar. Some seeds may dry sufficiently by utilizing a fan in a seed drying cabinet. Avoid using a food dehydrator to dry seeds as they usually get too warm and damage the seed.
Breaking Seed Dormancy
Many perennials have cold treatments or other requirements for successful germination and many will take several years for the plant to become large enough to flower. Research the growing requirements for any perennial to understand what special germination requirements are needed to grow them from seed.
Scarification - Breaking the Seed Coat
In some perennials, dormancy results from a thick, hard seed coat. To germinate, the seed coat must be broken. This process is called scarification.
The seed coat may be broken in various ways. Mechanical means, such as a metal file or coarse sandpaper, can be used to break the seed coat, especially on large seeds. Treatment with boiling water can also be successful for several perennial species. In nature, the seed coat may be broken by microbial action, passage of the seed through the digestive tract of a bird or other animal, exposure to alternate freezing and thawing, or fire.
Stratification - Providing a Cold Treatment
The seeds of many species will not germinate until they have been exposed to cool temperatures and moist conditions for several weeks or months. Winter weather in Iowa provides the necessary conditions to break dormancy. When the seed is planted in the fall, Mother Nature provides the stratification naturally. Gardeners can accomplish the same results through a process called stratification.
Seed can be stratified by placing the seed in a moist 50:50 sand and peat moss mixture. Suitable containers include coffee cans, plastic jars, and cottage cheese containers. (Punch holes in the lid of the container to provide air.) Seed can also be stratified in plastic bags. Stratify the seed in the refrigerator. For most species, stratify the seed at 32° and 40°F for 3 to 4 months. The best temperature and time frame for a particular species will differ.
Both Treatments May be Needed
The seeds of some perennials have hard, impermeable seed coats and dormant embryos. They require both scarification and stratification for germination. For these species, provide the scarification first, then the stratification treatment.
Set-up
Nursery Bed
In many situations, the most straightforward way to grow perennials from seed for the home gardener is to plant them outdoors in a nursery bed, allowing Mother Nature to satisfy the scarification (breaking seed coat) and stratification (cold treatment) requirements. A nursery bed is a temporary location to germinate and grow your perennials. The seed is sown close together with the knowledge that they will not have space in the nursery bed to grow to full size but will instead be transplanted to a permanent location once they are large enough and have developed a healthy root system.
It is much easier to pamper your seedlings when they are all growing together in a single nursery bed rather than trying to care for individual seedlings or plantings in isolated locations around the garden. These beds should be situated in protected locations out of harsh winds and intense sunlight. Keep the area weed-free to prevent crowding out. Having a water source nearby makes it easier to provide the frequent light waterings needed by seedlings with small, limited root systems.
Fence the area to prevent animals such as rabbits or deer from eating the newly emerged seedlings and prevent animals such as mice or chipmunks from digging up recently sown seed. Fencing may be required on the sides and top if animal pressure is high.
Utilizing a cold frame can help prevent damage from heavy rains or cold temperatures and extend the growing season to allow for more growth.
Many perennials sown in a nursery bed in the fall should be sown 8 to 10 weeks before the first frost. Although the timing the best suits any particular species will vary.
Indoors
Growing seeds in a nursery bed has advantages but can also create some difficulties. Extreme weather (wind, rain, temperatures) can kill young seedlings, and germination rates are often lower in these outdoor laissez-faire style set-ups. Starting seeds indoors allows you to provide ideal growing conditions, improving the germination rates and allowing more seedlings to reach a larger size. Additionally, you can grow seedlings year-round, allowing you to get plants to a larger size more quickly, reducing the time it takes to get plants to a blooming size.
When grown indoors, the gardener must provide any necessary scarification or stratification treatments. Stratification is often best achieved in a refrigerator. See the section above (Breaking Seed Dormancy) for more details on scarifying and stratifying your seed.
Once dormancy has been broken, the process looks virtually identical to starting the seeds of more commonly grown vegetables and annuals. Learn more about soil, light, moisture and other essential requirements on seed starting in this article: How to Successfully Start Seed Indoors.
Easy Perennials to Grow From Seed
While any perennial could potentially be grown from seed, these perennials are relatively easy because they have simple germination requirements and grow to blooming size quickly.
- Columbine (Aquilegia spp.)
- Ornamental Onion, Chives (Allium spp.)
- Pinks (Dianthus spp.)
- Catmint (Nepeta spp.)
- Purple Coneflower (Echinacea spp.)
- Black-eyed Susan (Rudbeckia spp.)
- Oriental Poppy (Papaver orientale)
- Anise Hyssop (Agastache spp.)
- Blackberry Lily (Iris domestica syn: Belamcanda chinensis)
- Hollyhock (Alcea rosea)*
- Beardtongue (Penstemon spp.)
- Balloon Flower (Platycodon grandiflorus)
- Delphinium (Delphinium spp.)
- Butterfly Weed (Asclepias tuberosa)
- Blanket Flower (Gaillardia spp.)
- Yarrow (Achillea spp.)
- Perennial Salvia (Salvia spp.)
- Catchfly (Silene spp.)
- Rose Campion (Lychnis coronaria)
- Tickseed (Coreopsis spp.)
* a biennial that often behaves as a perennial in the garden
Germination Requirements for Specific Perennial Species
Specific information on germinating seed for several easy-to-germinate and common garden species follows.
Yarrow | Anise Hyssop | Hollyhock | Columbine | Milkweed | False Indigo | Tickseed | Delphinium | Purple Coneflower | Daylily | Hosta | Iris | Blackberry Lily | Catmint | Oriental Poppy | Beardtongue | Balloon Flower | Salvia | Goldenrod
Yarrow (Achillea spp.)
Yarrow requires no special pretreatments to germinate. The ideal germination temperature is 65°F to 70°F. Sow seed and seedlings should emerge 10 to 15 days later. You can lightly cover the seed or leave it exposed to light during germination.
Anise Hyssop (Agastache spp.)
Hyssop does not require a cold treatment, but cold, moist stratification will improve germination rates. The ideal germination temperature is 70°F to 75°F. Cover the seed lightly, as exposure to light improves germination rates. Seedlings emerge 1 to 4 weeks after sowing. Plants started in fall will bloom the following summer.
Hollyhock (Alcea rosea)
No special pretreatments are necessary to germinate. Seedlings emerge 5 to 10 days after sowing when soil is warm (70°F) and 10 to 21 days in cooler soil. Lightly cover the seed during germination. The seed needs good soil contact, but light aids germination, so don't bury it too deeply. Seed sown outdoors from spring until two months before frost will bloom the following summer.
Columbine (Aquilegia spp.)
Columbine germinates readily with no pretreatment. The ideal germination temperature is 70°F to 75°F. Do not cover the seed, as light is needed for germination. New seeds will germinate in 10 to 20 days; older seeds (over a year old) may take up to four weeks to emerge. If germination does not occur in four weeks, move flats to cold storage (40°F) for approximately three weeks. Do not overwater when being stratified.
Butterfly Weed (Asclepias tuberosa)
While seed sometimes germinates without stratification, the best germination rates come with 3 to 4 weeks of cold storage (40°F). The ideal germination temperature is 70°F to 75°F. Seed can be covered or left exposed during germination. Germination occurs in 3 to 4 weeks.
False Indigo (Baptisia spp.)
Seed benefits from scarification. Knick the seed with a knife or sandpaper. Do not damage the seed; just break the outer coat. Soaking seeds in hot (not boiling) water overnight and then providing two weeks of cold (40°F) moist stratification will also improve germination rates. All of this can be skipped if freshly harvested seed is used. Cover seeds when sowing, and seedlings should emerge in 1 to 2 weeks.
Tickseed (Coreopsis spp.)
Tickseed is easily grown from seed. No pretreatments are necessary, although germination is better up to 8 weeks of cold (40°F), moist stratification. The ideal germination temperature is 65°F to 75°F. Seed can be covered or left exposed during germination. Germination occurs in 9 to 12 days.
Delphinium (Delphinium spp.)
No pretreatments are necessary. Fresh seeds should be used. Ideally, sow seed within six months of harvesting. Germination rates drop significantly after six months, and in many cases, it is better to source new, fresh seed than to try and grow older seed. Cover the seed lightly after sowing (vermiculite works well). Germination takes 12 to 18 days. Even with the best of conditions, germination may be spotty.
Purple Coneflower (Echinacea spp.)
No pretreatments are necessary. The ideal germination temperature is 65°F to 70°F. Cover lightly with soil, and the seed will germinate in 3 to 4 weeks.
Daylily (Hemerocallis spp.)
For best germination, stratify the seed for six weeks at 40°F. Cover seed after sowing. The ideal germination temperature is 68°F to 70°F. Seeds germinate erratically, some emerging after two weeks and others not emerging until seven weeks later. Be patient, and don't give up on a seed lot too quickly.
Hosta (Hosta spp.)
Provide cold (40°F) moist stratification for 2 to 3 weeks. Stratification can sometimes be skipped when sowing fresh seed. Cover seed after sowing. The ideal germination temperature is 68°F to 72°F. Seeds emerge after 2 to 3 weeks. Plants typically take 4 to 5 years to grow large enough to divide.
Iris (Iris spp.)
Provide cold (40°F) moist stratification for three months. Cover seed after sowing. The ideal germination temperature is 50°F to 65°F. Seedlings can emerge after one month but some can take as long as one year to finally germinate. Seedlings will exhibit a lot of diversity often being quite different from the parents.
Blackberry Lily (Iris domestica syn: Belamcanda chinensis)
No pretreatments are necessary. The ideal germination temperature is 70°F to 72°F. Cover seed after sowing. Germination occurs in 15 to 25 days.
Catmint (Nepeta spp.)
No pretreatments are necessary. The ideal germination temperature is approximately 70°F. Seeds require light to germinate so do not cover. Germination occurs in 7 to 14 days.
Oriental Poppy (Papaver orientale)
No pretreatments are needed. The ideal germination temperature is 65°F to 70°F. Seeds require light to germinate so do not cover. Germination occurs in 7 to 14 days. Direct sowing is often best for this species as it can be difficult to transplant.
Beardtongue (Penstemon spp.)
Plants germinate best with 3 to 8 weeks of cold (40°F) moist stratification. The ideal germination temperature is 70°F. Surface sow seeds; do not cover. Germination occurs in 1 to 3 weeks. Timing of stratification and germination varies (sometimes widely) by species.
Balloon Flower (Platycodon grandiflorus)
No pretreatments are necessary, but germination rates will be higher with seed less than six months old. The ideal germination temperature is 65°F to 70°F. Lightly cover the seed (to prevent drying), but the seed will germinate best when exposed to light. Do not let the germinating seed dry out. Germination can vary depending on seed age - 1 to 4 weeks.
Perennial Salvia (Salvia spp.)
No pretreatments are needed. The ideal germination temperature is 72°F. Surface sow, do not cover seed. Germination typically occurs in 1 to 2 weeks. Germination rates are often better when provided one month of cold (40°F) moist stratification.
Goldenrod (Solidago spp.)
No pretreatments are necessary. The ideal germination temperature is 50°F to 70°F. Cover lightly with soil, and the seed will germinate in 1 to 3 weeks.
Sources
- Making More Plants by Ken Druse (2012)
- New England Wild Flower Society Guide to Growing and Propagating Wildflowers of the United States and Canada by William Cullina (2000)
- Ball Perennial Manual by Jim Nau (1996)
More Information
- Propagating Woodland Wildflowers
- Guide to Starting Seed Indoors
- How to Harvest and Store Seeds
- Germination of Tree Seed
- How to Divide and Transplant Perennials
- How to Plant Perennials
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