By Jen Smith with input from the Propagation Committee
Native Seeds Germination Methods
Scatter Seeds Outdoors at the Beginning of an Early Winter Snowstorm
The snow will blanket the seeds, gently pressing them into the soil and providing initial moisture. It mimics the process seeds go through in nature. Make sure you’ve scattered the seeds where you want them to sprout! With this method, some seeds may be eaten by wildlife and it can be difficult to ensure the seeds have adequate moisture throughout the winter and spring. However, even if you get just a few seedlings, what an easy way to get them!
Winter Sow Native Seeds in Milk Jugs or Plastic Containers
These containers will serve as mini-greenhouses once you seal them while allowing moisture to enter and giving the seeds adequate drainage. As a result, they retain moisture better, which increases germination particularly as temperatures warm in the spring. However, there is work required to set these up and monitor them.
Check out the below video demonstrating how to sow native seeds in milk jugs. This was from an in-person workshop co-sponsored by the Colorado Native Plant Society, the Colorado Springs Horticultural Department, and Wild Ones Front Range.
This next video, Get Native Plants the Cheap Way by Winter Sowing, features Jennifer Frazer1 and her friend, demonstrating how to sow seeds in plastic bags. Jennifer also provides step-by-step instructions in How to Sow Native Seeds in Milk Jugs and Plastic Containers.
Sow the Seeds Outdoors in Cells
This approach allows for easy transplanting and/or bumping up of seedlings since they germinate in cells. The open cells do dry out faster than the container method, above, so more frequent monitoring and watering will be required. Here is a step-by-step Colorado Native Seeds Starting Guide to help you sow native seeds in this way. For much more information, please refer to the Germination Guide for Native Seeds compiled by WOFR member Jan Midgley. Jan will be updating this guide as her research progresses. And, Rob Greer, another Wild Ones member has put together a Germination Techniques Overview.
And, if you are very new to growing native plants from seed, we have compiled a list of Easy to Grow Colorado Native Plants that are suitable for novice growers. These seeds meet the following criteria: they need little to no pretreatment; germinate readily; are easy to grow in all kinds of soil; and are easy to collect.
Just remember that not all seeds germinate. The success rate varies by plant, but it is normal to get a less than 50% germination rate. Seed-grown plants can perform better than plants purchased from a nursery because they are typically grown in conditions closer to their final site and are often planted smaller than nursery plants. This “pre-adaptation” and quick establishment in the permanent location can give plants a real leg up over their counterparts matured in “cushier” conditions.
Soil Mix for the Best Germination
Many people have had success germinating native seeds in potting soil. Remember that with commercial potting mixes, you get what you pay for (at best), and caveat emptor. One of our members, Brian Rasmussen, decided to test sowing the same seed species in two different soil mixes and compared the results. For three species, Brian sowed the left half of the flat in Black Gold Seedling Mix and the right half of the flat in his homemade native soil mix. The pictures below demonstrate that the native soil mix was the clear winner!
Brian’s native soil, at his home in Boulder County is decomposed granite from a forest slope, and he is at 8200 feet in elevation. The native soil he uses has a very high mineral content – lots of rock and gravel. He amends this decomposed granite with approximately 5-10% compost. Then, the soil is screened with a ¼” screen to remove the larger mineral/rock and larger compost pieces. Then, he mixes 1 part Perlite to 3 parts soil.
After adding seeds, Brian puts a sprinkle of native soil mix as a top dressing. The top dressing is the native ¼” screened soil mix after sifting out the finer particles with a metal kitchen strainer/screen. The result is a native “squeegee” like material, similar to coarse sand.
It’s important to note that the seeds Brian is germinating are native to the soil he is using. And he germinates outside in natural winter conditions at 8,200 feet in elevation. You can find Brian’s complete process here (need to insert link).
Common Propagation Questions & Answers
Question # 1: When literature recommends 30 days-, 45 days-, 60 days-, or 90 days- cold stratification, is that number a floor or a ceiling? ie. if for simplicity, a grower started everything at a longer-than-recommended period, will that ruin the seeds requiring less?
Answer: The number of days of stratification is a floor. Most things can tolerate a longer period of time if they are in a container. In the refrigerator, the radicle(s) might emerge and then you have to get them into soil. I think grasses are an exception. You can lose a lot of the seeds to rot (or birds, if sown in situ) if you sow them before March.
Question # 2: I’m curious about the size of the seed containers. Jan was using quite small cells in her demonstration. Is there a propagation reason (as opposed to, say, a budget or storage reason) not to simply start everything in larger containers (maybe deep pots)? Seems like starting in larger containers would avoid the need for pricking out and moving the seedlings.
Answer: The biggest risk of large pots is overwatering and rotting your seeds or seedlings. Cells are handy for folks sowing a lot of different species or working in greenhouses. If you do sow in pots, narrower and deeper is better for 2-3 seeds. Well draining soil is important too. A number of us are thinking that a portion of native soil (for mycorrhizae?) is also helpful.
Join the Propagation Committee to Learn More
All Wild Ones Front Range members are welcome to join our Propagation Committee. The committee discusses and tests propagation techniques and updates these Best Practices with what they learn. It’s a fun community of people who are passionate about growing more native plants. Email us with your interest!
Curious to learn more about transforming your garden into a habitat with Colorado native wildflowers, grasses, shrubs, and trees? Check out our native gardening toolkit, register for an upcoming event, subscribe to our newsletter, and/or become a member – if you’re not one already!
- Jennifer Frazer is an enthusiastic home gardener and biologist turned science writer who for nine years wrote a natural history blog at Scientific American called “The Artful Amoeba”. She’s been propagating her own plants via winter sowing in plastic bags for six years for use in her own garden, which takes up the whole back yard, and last year when she discovered the importance of native plant gardening she resolved to propagate her methods too. She has taught mushroom and lichen classes for the Boulder County Nature Association and the Rocky Mountain Conservancy and was twice a featured guest on Radio Lab, speaking about the fungi that live in association with tree roots and about plant intelligence (From Tree to Shining Tree and Smarty Plants episodes). She is currently writing a book about slime molds. ↩︎