Winter sowing, aka cold stratification

– Posted in: Seeds and Seed Starting
11 comments

Winter sowing, as far as I can tell, is identical to what, in my self-education as a gardener, I learned as cold stratification. The more traditional description of the procedure is to put the seeds in the fridge for the requisite period of time, and then sow them in pots or flats or whatever your technique is for seed starting.

I learned stratification from Lauren Springer’s book The Undaunted Garden: Planting for Weather-Resilient Beauty. Her method is similar to what is commonly referred to as winter sowing now, but she didn’t bother with greenhouse-like containers to protect the pots of seeds. Instead, she covers the soil mix with “one-eighth inch of fine gravel (one or two grades coarser than sand)” and after watering them from the bottom, she puts “them outside on the north side of my shed, which stays shaded throughout the winter. This prevents the seed from experiencing the wide temperature fluctuations of warm, sunny winter days.” They aren’t covered because “The ideal cover…is a blanket of snow.”

This made sense to me, as it closely mimicked how the seeds would sprout in their native land under natural conditions, while still allowing the gardener the measure of control that most gardeners desire (like, knowing the names of the seeds that have sprouted). And when I tried it, it worked. This winter, observing that we have been having alternate thaws and freezes (it’s raining and 42F right now), I decided to use milk jugs and keep the containers on my porch. Even Lauren Springer says “if one lives in a climate with much winter rain, a cover over the pots is a great help,” and by keeping them on the porch, I am less likely to forget to check the moisture level of the pots when things get warmer in spring.

For the most part I have gotten away from growing plants from seed, after realizing that I never got the seedlings in the ground on time. But when Talitha was sorting through the family seed collection I found some perennial seeds for Iris setosa and Lobelia cardinalis and thought it would be nice to have some plants. And I also harvested some colchicum seeds and decided to try my hand at that as well.

Sowing seeds is a hopeful act, and preferable to moping about the length of winter. Unlike some people, I don’t expect to see crocus sprouts for another month, at least.

About the Author

Kathy Purdy is a colchicum evangelist, converting unsuspecting gardeners into colchicophiles. She would be delighted to speak to your group about colchicums or other gardening topics. Kathy’s been writing since 4th grade, gardening since high school, and blogging since 2002.

In the end, this may be the most important thing about frost: Frost slows us down. In spring, it tempers our eagerness. In fall, it brings closure and rest. In our gotta-go world–where every nanosecond seems to count–slowness can be a great gift. So rather than see Jack Frost as an adversary, you could choose to greet him as a friend.

~Philip Harnden in A Gardener’s Guide to Frost: Outwit the Weather and Extend the Spring and Fall Seasons

Comments on this entry are closed.

Lynn July 18, 2008, 1:43 pm

Thanks for demystify this for me, Kathy. I’ve just come across “winter sowing” resources and want to know more (and your post was on the first Google page). Growing from seed would help us re-do a front yard much more economically (I hope). This helps 🙂

Kim February 14, 2008, 8:52 pm

Interesting post, Kathy. At the risk of stirring up something, I will say that certain people who have laid claim to “creating” winter sowing have always kind of made me raise my eyebrow at their sometimes militant stance on the issue, because I’m sure it had been done before…

In any case, I was also interested in the idea that cold stratification, winter sowing, whatever you want to call it, should be done on the north side of the house. Ever since I moved here, I’ve done mine on the south side–because it was right outside my side door, and I would see and remember the little containers to check them every once in a while!

Shady Gardener February 10, 2008, 10:58 pm

Encouraging post. Perhaps I’ll get out some soil and seeds YET! 🙂

Neil Moran February 10, 2008, 12:29 pm

I stratify native perennial seeds in my refrigerator. I do this in ziplock bags and chewing tobacco containers. I mix in enough potting mix to keep it moist. Works well, but keep an eye on it, in some cases it may sprout! Once, I did Sorbus seeds this way and they sprouted. I caught it in time and went on to grow some nice Mountain Ash trees.

wiseacre February 6, 2008, 8:31 am

I wasn’t familiar with Iris setosa so I went ad looked it up. I found some interesting info at Dave’s Garden:

Now I wonder if I haven’t actually seen them or a hybrid in the wild and mistook them for the more common Iris versicolor.

jodi February 6, 2008, 12:15 am

Between you, and Nan Ondra, and a few others, I’m actually starting to psyche myself up for doing this. I don’t have the room or the time indoors to start a lot of seeds–plus the eight little catchildren like to “help’ when I do start seeds, but I’m really tempted to do some perennials outdoors. Not quite there, but if I keep thinking about it…this is a long nasty winter and a little puttering in soil would do me good.

Carol February 5, 2008, 11:05 pm

Kathy, excellent point that winter sowing is all about cold stratification. Most of the seeds I sow are for the vegetables, so I do those inside.

And thanks for the link. After the rains we’ve had, my crocus might have drowned.

Carol, May Dreams Gardens

Curtis February 5, 2008, 8:30 pm

My front porch faces north so keeping them from the winter sun is no problem here. Thanks for the tip.

Bonnie Story February 5, 2008, 5:01 pm

Hi again Kathy,
I found you thru the Heronswood Voice. Heronswood Nursery is still a huge name around here, despite having closed.

Are you familiar with my part of WA, the Toandos Peninsula? It’s pretty much zone 8 in the books but I’m going to plan towards zone 7 and 6 just to be a bit more conservative. This is a pretty bitter winter we are havin’.

We just moved from CA to WA and absolutely love it here. Bought the place 3 years ago and just 4 months ago came up to live.

http://back2theland.blogspot.com/

Also my dog has a blog… I’m codogpendent!
http://sonomadoggybloggy.blogspot.com/

Thanks so much for your excellent blogs and for your encouragement! I look forward to reading future posts.

Very sincerely, Bonnie

Kathy Purdy February 5, 2008, 2:52 pm

Thank you for stopping by and expressing your appreciation, Bonnie. Looks like I could learn a lot from you, too. Great looking site you have there. Do you have a blog by any chance?

Bonnie Story February 5, 2008, 2:43 pm

Great blog, Kathy. You write really well and I have learned quite a bit from exploring your archives too.