Here I will teach you what cold seed stratification is, as well as scarification. Learn when both are appropriate to use and on what seeds. Then see how to perform both so that you can have top rate seed germination this year.
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First, let’s talk about scarification.
what is seed scarification?
Seed scarification is the process of scratching or scraping off a small amount of the outer tough layer of the seed to “scar” them. This is generally done to larger, tougher seeds prior to performing cold seed stratification.
why scarify your seeds?
Some seeds have a tough outer layer that can be difficult for moisture to penetrate. Scarifying them allows water to penetrate into the seed to aid in germination.
How do I know if I need to scarify my seeds?
Whether you need to scarify your seeds will usually be indicated on your seed packet instructions.
how to scarify your seeds
First, pour your seeds onto a piece of sandpaper
Then fold the sandpaper in half over the seeds
Rub the seeds between the sandpaper enough to scrape up the outer coating of the seeds.
Finally, plant as indicated on seed packet or cold seed stratify as needed.
Now let’s talk about cold see stratification.
What is Cold seed Stratification?
Cold seed stratification is the process used to mimic the winter dormancy period and temperature cycle that some seeds must go through in order to germinate well.
Why cold stratify your seeds?
When seeds are in storage they are kept cool and dry. But, in nature, many seeds would enter a dormancy period over winter when temperatures drop and the soil is cold and moist. Without this cold dormancy period, germination rate would be considerably lower. The warm, moist temperatures in the Spring break this dormancy and promote growth.
How can you tell what seeds would benefit from cold seed stratification?
This process is required for fruit seeds, trees and shrubs from temperate or cold climates, some flowers, and some herbs, most of which will be perennials.
Usually this would be indicated on the instructions of the seed packet. There are many seed packets that do not instruct this as it can be considered optional by some. To be sure, a quick internet search can tell you if your particular variety would benefit.
what are some common seeds that require cold seed stratification?
Here are some common plants that require stratification. this is not an exhaustive list. Please research your individual seeds before beginning stratification.
- Anise hyssop (Agastache foeniculum)
- Balloon Flower (Platycodon)
- Beard-tongue (Penstemon)
- Black cohosh (Actaea racemosa)
- Black-eyed Susan, most types(Rudbeckia)
- Blue cohosh (Caulophyllum thalictroides)
- Buttercup (Ranunculus)
- Butterfly Bush (Buddlejah)
- Catmint (Nepeta)
- Chinese Lantern (Physalis)
- Christmas & Lenten Rose (Helleborus)
- Coneflower (some varieties)
- Creeping Mazus (Mazus)
- Crimson Scabious (Knautia)
- Echinacea (Echinacea purpurea, E.angustifolia)
- Edelweiss Leontopodium)
- Evening Primrose (Oenothera)
- Hardy Hibiscus (Hibiscus)
- Hyssop (Agastache foeniculum)
- Lavender (Lavandula)
- Lupine (Lupinus)
- Marsh Marigold (Caltha palustris)
- Marshmallow (Althaea officinalis)
- Milkweed (Asclepias)
- Candytuft (Iberis)
- Sunflowers (Helianthus)
- Sweet Pea (Lathyrus)
- Peruvian Lily (Alstroemeria)
- Phlox (all types)
- Pincushion Flower (Scabiosa)
- Plume Poppy (Macleaya)
- Prairie Coneflower (Ratibida)
- Primrose (Oenothera speciosa)
- Primrose, all types (Primula)
- Shooting Star (Dodecatheon meadia)
- Skullcap (Scutellaria lateriflora)
- Soapwort (Saponaria ocymoides)
- St. John’s Wort (Hypericum perforatum)
- Stokes’ Aster (Stokesia)
- Violets (Viola)
- Virginia Bluebells (Mertensia)
- Waxbells (Kirengeshoma)
- Wild Geranium (Geranium maculatum)
- Wild yam (Dioscorea villosa)
how to cold stratify your seeds
Lay out a paper towel on a plate.
Spray the paper towel with water. Do not oversoak it or your seeds may rot. You want wet but not dripping.
Sprinkle your seeds over the wet paper towel.
Fold in half
Fold in quarters
Store in a plastic bag in the refrigerator for two to four weeks or as indicated on the seed packet.
Check your bags regularly to add water as needed. You want the paper towel moist but not sopping wet and not dry either. Once this process has been completed you can plant as instructed on your seed packet.
What do I do if my seeds start sprouting in the fridge?
This can happen sometimes and it is perfectly okay. Plant them as you normally would. Sometimes if they have been sprouting for too long the roots can begin to grow into the paper towel. Just try to be sure you do not rip off the roots when removing them.
Can’t I just plant seeds that require stratification in the fall?
Yes! You can plant seeds in the fall as soon as the temperatures cool down but before the ground freezes solid. Alternately, you can also plant them in the early spring if the ground is workable and your forecast calls for at least a month more of freezing temperatures.
Some concerns with doing this though is the potential for some seeds to rot in the ground, or be eaten by birds before they can germinate.
Are there any other ways to cold seed stratify?
Yes, there are a few more ways. Fall or early Spring planting is an option, as mentioned above. You can put the paper towel into a jar as well as skip the paper towel altogether and opt for a jar of cold water. This would need to be changed daily though and straining out the tiny seeds can be difficult.
One more way would be to put your seeds in a covered plastic container filled with a mixture of sand and peat moss or jiffy peat pellets. Moisten the soil and plant as you would when seeds starting. This can then be store in the refrigerator for the four to six weeks. Many people don’t necessarily have the storage in their fridge that this method would require though.
Are there any other ways to scarify your seeds?
Yes! you can individually run each seed over the sandpaper or you can scrape each one with a sharp knife or razorblade as well. Just be careful not to cut yourself!
Thank you for coming to learn about cold seed stratification and scarification. I hope you found value here. Please leave me a note in the comments if you found this information helpful!
Great info. Thanks!
Fascinating!!! Had no idea that these were necessary processes.
I’m glad you find it interesting! Just remember, it is not necessary for vegetable seeds.
Mandi Lynn in MN says
Wow! Thank you for taking the time to do this! I’m only in my 3rd year of gardening and have only planted annuals thus far. I’ve had much success and I’ve finally got my beds ready for their permanent plants. I have milkweed, roses,viola,lupine,sunflowers and quite a few other seeds as well. Doing the research has been pretty frustrating, just trying to find anything with the process and the pictures and the details! I’ve saved this for future reference as well. Thanks again!!
You’re welcome! I am glad you found value in it! Happy Gardening!