
by Emily Skelton
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"Every species has some mechanism for delaying
germination until after the seed has dispersed."
- Norman C. Deno, Seed Germination Theory and Practice |
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Nature has designed seeds to germinate at an optimal time of year for each species. Many seeds enter a period of waiting as soon as they fall from the parent plant. For most vegetable varieties a combination of warm temperatures and moisture is all they need to start germinating. Many perennial flowers and herbs, however, have germinating mechanisms that are slightly more complex.
Light
affects
germination |
Some seeds have delay mechanisms that are altered by the presence or absence of light. For seeds where light inhibits germination, bury the seed. Some species require light to germinate: sow these on the surface. |
Temperature
affects
germination |
Temperature is a major variable in seed germination. Some seeds require cold periods of approximately 35-40°F to alter their delay mechanisms. Some genera (e.g., cleome) germinate better after periods of oscillating temperatures such as occur in the spring. |
Moisture
levels
affect
germination |
Germination in response to moisture
indicates a delay mechanism that waits for a rainy season (all seeds). Some species
germinate better after dry storage. Natural deterioration occurs with all seeds in dry
storage. Some deteriorate after only a short time, but most seeds last one to two
years. Others can live 100 years (usually seeds with impervious seed coats). |
Time
affects
germination |
Time works in conjunction with the above three conditions. E.g., Echinacea paradoxa needs 2-3 months of cold to allow enough
time for the chemical changes to occur. |
For the varieties that need special treatment, we can simulate the conditions their seeds need to germinate. Below we'll discuss the different germination methods and give special recommendations on germination techniques for the perennial flowers and herbs that we carry in our catalog.
Three Methods For Simulating Natural
Seed Germinating Conditions
SCARIFICATION
Some seed has an impermeable seed coat which causes a physical barrier to germination. Scarifying, chipping or drilling the seed coat, removes a small sliver from the side of a seed. Through this hole the seed can imbibe water. For small seeds, try rubbing them gently on sand paper. Plant the seed immediately or soak it for 24 hours in warm water (Lupinus spp., Baptista australis, Lathyrus spp.) See table below for a list of varieties offered in our catalog that germinate better with scarification.
SURFACE SOWING
Seeds that are dependent on light to germinate need to be planted on the surface. It is very important for the seed to have good contact with the planting medium (for our soilless potting mix tips, click here). Press seed firmly into the medium. Keep moist until germination. You can cover with clear plastic to enhance moisture retention. As soon as the seedling appears remove any covering. See below for a list of varieties offered in our catalog that require surface sowing.
COLD STRATIFICATION
Can be done in several ways...
| Outdoor Sow |
Sow in Flats or Pots |
Sow in Paper Towels or Soilless Medium in Plastic Bags |
| Sow seeds in the ground outside in early spring when temperatures fluctuate wildly and frost still occurs or sow outdoors in the fall. Make sure to label, record in a notebook, or make a map. You can also sow seeds in flats inside plastic bags and store them outside in a cold frame over the winter. |
Fill pots or flats with soilless mix, moisten but don't saturate, sow seeds in individual cells for easy recognition and less thinning. Place containers in plastic bags with a small hole for circulation (avoid extra-thick freezer bags as they do not breathe.) Label with name and date. Place in refrigerator for a predetermined time depending on species. Keep moist. |
Position seeds between folds of moist, extra strong, folded paper towels or in moist soilless medium (Mix equal parts sand, vermiculite and peat or coconut fiber). Place inside thin walled, slightly open plastic bags. Label with name and date. Place in refrigerator. Check for moisture periodically. |
| Disadvantages to this method: Forgetting where you planted the seeds. Tags get lost. Birds and rodents may eat the seed. Plants are subject to weed pressure. Insufficient moisture for surface sown seeds and they don't germinate. |
Disadvantages of this method: Not enough room in the refrigerator for your food and the seed flats&emdash;you have to choose whether you want to eat or want a gorgeous garden. |
Disadvantages of this method: Still need to plant the wet seeds. In soilless medium in bags, seeds are somewhere within the mix. (Spread it evenly in an open flat filled with soilless seed starting mix. Thin seedlings later.) |
Specific Germination Techniques for Our Flowers
(Note: some varieties need more than one treatment.
These are listed in more than one column.)
| Scarify |
Cold Stratify |
| Botanical Name |
Common Name |
Botanical Name |
Common Name |
Alcea rosea
Baptista australis (soak 24 hours in warm water)
Lupinus pilosus (soak 24 hours in warm water)
Lathyrus odorata (soak 24 hours in warm water)
Malope trifida
|
Hollyhock, Single Mix
Indigo, False Blue
Lupine, Mt. Blue
Sweet Pea, Royalty Mix
Mallow, Purple Spanish
|
**Aquilegia vulgaris (14-21 days)
Asclepias curassavica (14-21 days)
Belamcanda chinensis (7 days)
Cleome hasslerana (14-21 days)
**Delphinium elatum (14-21 days)
*Lobelia cardinalis (56-70 days)
Polygonum orientale (14-21 days)
*Salvia spp. (14-21 days, seeds short lived)
|
Columbine, 'Mckanna's'
Blood Flower
Lily, Blackberry
Cleome, Purple Queen
Delphinium, Belladonna Blue
Cardinal Flower
Kiss-Me-Over -the-Garden-Gate
Sage, New Mexico, Silver Downy Leaf, Texas Hummingbird, Victoria, Nemerosa
|
| Surface Sow |
| Botanical Name |
Common Name |
*Antirrhinum majus
Aquilegia vulgaris
Campanula persicifolia
Chrysanthemum x superbum
Cleome hasselerana
Coreopsis lanceolata
Coreopsis tinctoria
Digitalis purpurea
Echium vulgare
Gaillardia pinnatifida
Hesperis matronalis
*Impatiens balsamina
*Lobelia cardinalis
*Matthiola bicornis |
Snapdragon
Columbine, 'Mckanna's'
Campanula, 'Peach Leaf'
Daisy, Shasta
Cleome, Purple Queen
Coreopsis, Maroon
Coreopsis, Bouquet Magic Mix
Foxglove Foxy
Echium
Gaillardia, Blanket Flower
Dame's Rocket, Purple
Balsam, Garden
Cardinal Flower
Stock, Evening
|
*Seedlings susceptible to damping off (plants rot underground, at soil line, or crown). Sow in a very light soilless mix utilizing mostly perlite and vermiculite. Water from the bottom.
**Wet soil first then seed in pots/flats, cover with thin layer coarse dry vermiculite; refrigerate lightly covered in plastic as seed does not like to be too wet. Seedlings are delicate, plants like cool weather. |
Additional Germination Techniques for Our Herbs
| Scarify |
Cold Stratify |
| Botanical Name |
Common Name |
Botanical Name |
Common Name |
Althaea officinalis
Astragalus membranaceous
|
Marshmallow
Milk Vetch
|
Asclepias tuberosa (14-21 days)
Echinacea spp. (21-60 days)
Lavandula viridis (14-40 days)
Lobelia siphlitica (56-70 days)
Melissa officinalis (14-21 days)
Veronicastrum virginicum (14-21 days)
|
Butterfly Weed
Coneflower, Yellow, Purple, Pale Purple, Tennessee
Lavender, Yellow
Lobelia, Great Blue
Lemon Balm
Culver's Root
|
| Surface Sow |
| Botanical Name |
Common Name |
Achillea millefolium
Agastache foeniculum
Althaea officinalis
Angelica archangelica (seed short lived)
Artemesia vulgaris
Inula helenium
Matricaria recutita
Melissa officinalis
Mentha pulegium
Monarda fistulosa
Monarda punctata
Origanum hirtum
Rosmarinus officinalis
Tanacetum parthenium
Thymus vulgaris
Valeriana officinalis
Veronicastrum virginicum
Withonia somnifera
|
Yarrow
Mint, Licorice
Marshmallow
Angelica
Mugwort
Elecampane
Chamomile
Lemon Balm
Pennyroyal
Lavender Bergamot
Dotted Mint
Greek Oregano
Rosemary
Feverfew
Thyme, English
Valerian
Culver's Root
Ashwaganda
|
Norman Deno says, "to plant a seed is a noble deed," and that "propagation is conservation." By planting many of these herbs and wild flowers we are increasing diversity. This is one of our company's primary missions. These seeds will germinate if we learn what specific conditions they need and then simulate their natural environment using well-tested methods.
Emily Skelton
Seeds of Change Greenhouse Specialist
References:
Arnosky, Pamela and Frank. "Tricks of the Trade for Starting Flower Seed" - Article in Growing for Market (March, 2004).
Clothier, Tom. http://tomclothier.hort.net/index.html Excellent reference site for planting any perennial flower: has a large section devoted just to Penstemon spp. Has some good photos.
Deno, Norman C. Seed Germination Theory and Practice (1994, Second Edition).
Powell, Eileen. Seed to Bloom: How to Grow Over 500 Annuals, Perennials and Herbs (1994).


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