Saturday, February 11, 2012

Winter Sowing Seed Project: Part 2

In my ever-increasing quest for more native plants, and because as Oscar Wilde said, "More is never enough", earlier this winter I started a seed sowing project. Most native plant seeds need to experience a cold, moist period in order to trigger their DNA to germinate. This can either occur naturally out in a garden bed, outside in a container of soil, or inside in your refrigerator- then planted outside. Supposedly sowing seed directly in a bed produces the lowest germination rate because the seed is the most vulnerable to being washed away, eaten, covered up with debris, or otherwise re-located. I've read reports on the internet (and everything we read on the internet is true, right?) of higher success rates by sowing in containers left exposed to the elements or pre-treating in the fridge then sowing in containers. Theoretically we're controlling some of the variables which should lead to a higher success rate.

Back in December, I selected a few plants to experiment with and planted seeds both outdoors in the elements and indoors in baggies for the refrigerator method. This will be especially interesting this year since it has not exactly been a properly cold winter. Some seeds require as much as 60-90 days of cold, moist stratification, like Vernonia fasciculata (common ironweed) and I will be able to compare the results of the same seed with natural stratification and forced stratification. I won't be surprised at all if the Vernonia I planted outside doesn't germinate as well as the Vernonia seeds I stratified in the fridge thanks to not receiving adequate chilling time courtesy of our warm winter.

Seeds sown in outside in containers, rather than scattered on the ground

I'm also trying the "milk jug method" on a few seeds, but I'm finding they heat up quite a bit- not good if you need them to stay frozen or cold. Specifically I'm using the milk jugs for Columbine, which need to be surface sown and the jugs offer some additional protection.

By the way, the milk jug method is roughly as follows: take an empty, clean gallon milk jug and cut it in half almost all the way around, fold the top half back, fill with seed starting mix, seeds, water, tape shut, leave cap off to breathe, stick outside in the shade, then move into the sun in spring. You can also Google it and find lots more info and pictures.

Milk and Spring Water jugs, with Columbine seeds

Some seeds have already completed their 30 day treatment in my fridge and are ready to be planted outside. This afternoon I'll be potting up the Verbesina alternifolia (wingstem) and Verb. occidentalis (yellow crownbeard) and placing them outside to (hopefully) germinate when it warms up. These two are also seeds, like the Vernonia, that I also planted in flats outside and I'll be able to compare the germination rate between outdoor only stratification and refrigerator/outdoor stratification.

Pre-treated Verbesina seeds, ready to be planted

Even better are the plants that need no pre-treatment, like Monarda fistulosa (wild bergamot) and Echinacea purpurpea (purple coneflower). I decided to do another experiment to compare the germination rate, hardiness, and overall growth characteristics between starting some of these seeds early indoors under my grow lights, and outdoors in containers au naturale. The ones planted indoors, just last week, have already germinated. Woohoo! They're going to get a huge head-start before spring, this will be really interesting. Of course, the ones sown outside have not germinated yet.

Echinacea sprouts

Have you ever noticed how almost all seeds' first leaves look similar? Generic and round, perhaps to catch the most light. A seedlings second pair of leaves usually look most like the mature leaves of the plant it will become.

Monarda sprouts
Do you folks have any favorite plants or other native plant species you might recommend as easy and fun to start from seed?


  1. Hey Julie, congratulations on your 100th post!! Maybe this weekends hard cold snap will magically make up for all the warmish days and stratify all your seeds. Good luck and keep up the good work:)

  2. Hi Julie,
    We've tried all methods except the milk jugs. Have had the best luck with cold stratification in the fridge then sowing directly outside in a designated bed. Sowing into pots outside in fall had really poor results.

    Good luck, my husband grows ironweed every year and finds it an easy one to get tot germinate.