Use the Winter Sowing Method to Grow a Rainbow of Annual Flowers

By Jill M. Nicolaus (critterologist) April 3, 2008

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Winter is turning to Spring, and you still have a stash of empty milk jugs you were saving for “winter sowing?” Put them to use! It’s not too late to grow plants with the winter sowing method. In fact, in temperate zones, spring is the perfect time to sow annuals. With the great germination and survival rates of this method, you’ll have gobs of seedlings to plant out for an explosion of color in your summer garden.

The USDA Agricultural Library's Glossary defines the Winter Sowing Method as "a propagation method used throughout the winter where temperate climate seeds are sown into protective vented containers and placed outdoors to foster a naturally timed, high percentage germination of climate tolerant seedlings." This same winter sowing (WS) method can be used in early spring to give half-hardy annuals a good start.

My Groundhog's Day article, "Celebrate by Winter Sowing Your Seeds," details selecting, preparing, and planting WS containers. The method is just the same at this time of year. You need a covered, vented container that holds several inches of potting mix and provides seedlings with light, water, and drainage. With the stronger spring sunshine, it's even more important to find a location where your containers will be shaded from hot afternoon sun. A pinch of polymer moisture crystals added to your potting mix can help keep it from drying out, but you may have to do a little watering if you get hot days with no rain.

What annuals do especially well with the WS method? If you drop by the DG Winter Sowing Forum, you'll pick up all sorts of ideas for annuals that can be successfully winter sown. Some people start on the Winter Solstice in December; I like to wait until Groundhog's Day in February. Have you had any annuals reseed for you? When I find scattered volunteers of Petunias, Sweet Alyssum, Amaranthus, or other annuals I planted the previous year, I know I've got another great candidate for my winter sowing containers!

The timing of using the WS method for annuals depends on how the relative hardiness of the plant. Some of the annuals in our summer gardens are tropical plants that can't tolerate a hint of frost. Others, like pansies, may even be planted in fall to over-winter and come back the following spring, blooming like crazy. The more hardy the annual, the sooner you can sow it.

You may already have winter sown some hardy annuals. Hardy annuals can handle some frost and may even need cold stratification to germinate. Bachelor Buttons, Poppies, Violas, Snapdragons, Calendula and Cleome are some common hardy annuals that germinate readily with the winter sowing method. If you didn't sow them in February, go ahead and "winter sow" them now. If it's cold enough that you grab a jacket when you go out at night, it's cold enough to give those seeds the chilling that they like.

Half-hardy annuals can tolerate some chilly weather but may be damaged by frost. Marigolds, Love-in-a-Mist, Four O'Clocks, Cosmos, Petunias, and annual Salvias can be started by the WS method in early spring.

Tender annuals often wither at the least touch of frost. They can also be started in WS containers, but it's prudent to wait until the time for hard freezes is past. You can also direct-sow tender annuals after the soil warms up. Using the WS method gives them several weeks' head start, as the container serves as a sort of miniature cold frame. Morning Glories, Nasturtiums, Zinnias, Basils, and even Tomatoes can be started this way, especially cherry or other early bearing varieties.

The mini-greenhouse environment under the lids and domes of WS containers gives your seedlings extra protection against cold. Even so, if a hard freeze is forecast, I'd suggest covering containers with sprouted seedlings or moving them to shelter for the night. An unheated garage is a better choice than a warm house, as they'll have to re-adjust to outside temperatures when you move them back. Seedlings that have grown large enough to touch the sides and tops of their containers seem more likely to be damaged by cold.

Are there annuals that shouldn't be started with the WS method? Some annuals germinate best in warmer temperatures and may simply take too long to sprout outside, even in their little "greenhouse" containers. Annuals that take 10 or 12 weeks to bloom from seed should probably be started inside on light shelves. Otherwise, you'll only have a few days to enjoy their flowers before frost. Examples of common, slow-to-mature annuals are annual Geraniums, Wishbone Flower, Impatiens, Begonias, Heliotrope, some Petunia varieties, and Coleus.

This is about the time when I realize I will never have enough room on my light shelves for all the seeds I'd like to start this year. And it's such fun to have flats of annuals to plant all around the yard for a riot of color! I was delighted to learn I can continue to use the WS method as winter turns into spring.

Now my supply of annual bedding plants is limited only by my ability to scrounge milk jugs and other suitable containers. It's hard not to go overboard. I try to keep in mind that more plants = more digging and planting in a few weeks. But when it comes to having a rainbow of color in the garden, I'll just never believe that "less is more." Sometimes, more is more! Keep using the WS method this spring, and grow a rainbow of your own.

Photos by Jill M. Nicolaus. 

About Jill M. Nicolaus   Better known as "Critter" on DG, Jill gardens in Frederick, MD. This week, I've been cutting lavender, putting up pluots (plum-apricot fruits), and pulling weeds (always, LOL). I love being outside in the cooler morning -- coffee cup in one hand, watering hose in the other -- watching the birds and butterflies among the flowers.(Images in my articles are from my photos, unless otherwise credited.)

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Subject: Great!!!

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Posted by Jax4ever (from Boxford, MA) on April 3, 2008 at 1:24 AM:

I, too, will NEVER have the room indoors to start all the annuals I want to grow. What terrific news to hear that I can start planting some now!
I was going to try a very few of certain annuals outdoors as an experiment- now I have the confidence to plant a few more flats outdoors now!!!
THANK YOU, Jill!!!
P. S. I always feel guilty if I don't get around to planting all the plants I sowed. That's just silly! I do the best I can and that's that. Seeds cost pennies, and it's good to have too many than not enough!

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Posted by darius (from Marion, VA) on April 3, 2008 at 8:15 AM:

Good Article, Jill. Simple and easy to understand, and therefore encouraging a plan of action!

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Posted by critterologist (from Frederick, MD) on April 3, 2008 at 9:01 AM:

Thanks! It's amazing what a few packets of seed from the Dollar Store or the "cheap" rack at WalMart can turn into... and as I've become more confident about the WS method, I've been entrusting my more "special" seeds to it also.

It's wonderful to have flats of annuals to set out... I don't know about anybody else, but when I have to pay for them by the pot or by the 6-pack, I always come home with fewer than I'd really like, and I parcel them out very carefully in my containers and borders. Whether you start seeds inside or outside, by growing your own you can be lavish with them!

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Posted by CapeCodGardener (from Mid-Cape, MA) on April 3, 2008 at 10:01 AM:

Thanks, Critter-Jill! Loved the lists of plants you gave, in order of their hardiness. You've inspired me to get those seeds out into my milk jugs again!

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Posted by critterologist (from Frederick, MD) on April 3, 2008 at 10:14 AM:

:-)

There was some overlap and some disagreement between lists of hardy, half-hardy, and tender annuals from various sources... but I tried to pick a few examples that I figured were most likely to work out well, based on my own success with them and/or seeing success reports from folks in the WS forum.

There are lots of other annuals that will do fine with this method also, so don't limit yourself to the ones mentioned in the article!

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Posted by beth_donovan (from Easton, KS) on April 3, 2008 at 11:30 AM:

I really like this winter sowing! I have sown some seeds in flats under light and I'm sowing some of the same seeds the winter sowing method - so I can see which seeds do better with which method.

I had never heard of it until I found DG - it's just so easy to do!

Thanks for the great article!

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Posted by darlindeb (from Claremore, OK) on April 3, 2008 at 11:51 AM:

Loved it! It's nice when you can put your arrow on the pictures and find out what the plant pictured is. Another home run from Jill!

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Posted by Pamgarden (from Central, VA) on April 3, 2008 at 1:49 PM:

Jill, Great article. I enjoyed the Ground Hog Day article as well. I was looking for the Direct Seeding Forum when I saw your article. Maybe direct seeding is an intuitive thing, but it was surprising for me to learn that a delicate looking flower like cleome requires some cold to germinate. I've planted cleome seedlings, but they haven't come up. Maybe that's why. Do you think you might do an article on direct sowing?

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Posted by critterologist (from Frederick, MD) on April 3, 2008 at 2:18 PM:

Pam, I direct sow when I have bunches of seed to scatter around (like when I save or purchase big handfuls of zinnia seeds), but mostly I start seeds by some method that offers them a little initial protection. We have literally dozens of rabbits around here, so between them and the slugs that become an issue during wet springs, tiny seedlings out in the garden just don't have good survival rates for me. Also, I think I just don't pay close enough attention to things that are "way out there"... plants in pots on my deck or in flats on my seed starting shelves get a lot more TLC (and water when they need it).

Although there isn't (as far as I know) as Direct Seeding forum, you could probably get questions about direct sowing answered in the forum for whatever type of plant you're sowing -- veggies, perennials, etc.... hmm, the cottage garden forum might be a good place to ask, too.

Posts I've seen about Cleome seem to say that people have sowed it successfully later in spring (either directly or in WS containers) but that they get better germination when the seeds get some cold stratification.

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Posted by Jax4ever (from Boxford, MA) on April 3, 2008 at 2:46 PM:

I am considering doing an article on direct sowing, but it will have to be after this growing season. I've had better luck direct sowing perennial seed than annuals, but I have a few ideas to try this season. I actively garden the perimeter of my property- "way out there" b/c it's what I see from my windows, plus poses the greatest challenge. I can't water it as easily, so I'm trying to figure out how to keep seeds moist- but not soaked- while they germinate. On trick I'm trying this year is to put 1-3 seeds into a gel capsule w/ a few polymer crystals. I've pushed the capsule just under the soil (I did this last fall, b/f frost). Since it's been thawing, I've noticed little gel mounds here and there! I hope it works! (Of course, if it does, I'll be spending hours shoving seeds into gel capsules...groan..) I'm going to try it w/easy annuals, like marigold or zinnia.

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Posted by Sharran (from Calvert City, KY) on April 3, 2008 at 3:57 PM:

Great article, Jill, thanks.

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Posted by grampapa (from Wheatfield, NY) on April 3, 2008 at 9:25 PM:

Right on the money and just in time again, Jill. I'm out of room in the house. The seedlings are pushing my orchids out of their cart, we can't get near any of our windows, and all of my kitchen counters have shrunk because there are plants under the cabinet lights. Lots of room on the patio, though :0)

Thanks,
~ jan

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Posted by critterologist (from Frederick, MD) on April 3, 2008 at 11:44 PM:

:-) I know I can't make myself stop sowing when I've still got such a supply of nifty seeds! I'm glad I could pass along some good tips.

You're going to be very, very busy in a few weeks!

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Posted by Pamgarden (from Central, VA) on April 7, 2008 at 1:12 PM:

I really like the idea of perimeter sowing. I have many more seeds than beds to put them into thanks to some DG angels. I know I've seen wild flower mixes with some of the seeds. There is plenty of pasture beyond the area we've designated as lawn that I can experiment with, that is if the deer don't get them. Somewhere I read an article on someone who takes their seed, clay soil, a little potting soil and a little compost, wets it and rolls it into little terracotta like balls and throws them on waste space. Rain and weather break down the little balls and provide a small growing medium and some of the flowers take hold. She wrote that she had been doing this for years in a waste space near her property and it had become a real field of flowers. Does anyone recall this or know what it's called?

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Posted by critterologist (from Frederick, MD) on April 7, 2008 at 2:06 PM:

I've seen seed balls like that for sale, and they were very pricey for the amount of seed contained... you could probably direct sow 50 times the amount of seed for that price and get similar results. But I have considered making my own (they'd be a great little gift, too), just haven't gotten 'round to it, LOL. I think polymer moisture crystals would be another good addition to the seed/clay/compost mix. I wish I remembered who recently posted about putting seeds together with a few polymer moisture crystals in gelatin capsules... neat idea, but it sure sounded tedious! Then again, it would be as good as knitting for giving your hands something useful to do while watching a movie or TV show on a winter day. :-)

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Posted by kqcrna (from Cincinnati, OH) on April 7, 2008 at 3:40 PM:

Nice article, Jill.

Karen

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Posted by critterologist (from Frederick, MD) on April 7, 2008 at 5:33 PM:

Thanks, Karen!

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Posted by dianne99 (from Brookville, KS) on April 8, 2008 at 7:56 PM:

Thank you so much Critter. I have nothing ready for traditional seed starting this year--or the time to do it, but will not lose out this spring because of your article.

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Posted by critterologist (from Frederick, MD) on April 8, 2008 at 8:08 PM:

I hope you get some pretties to plant out! :-)

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Posted by Jax4ever (from Boxford, MA) on April 8, 2008 at 9:30 PM:

Karen, someone else is doing seeding w/ the capsules? I hope it worked! I'll do a search...
If you buy the size "000" it isn't that tedious b/c those are the biggest avail., the size of horse pills! I had them b/c I was using them to store pollen anthers. Gel capsules aren't the cheapest things in the world, either- generally 200 cost $8.

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Posted by critterologist (from Frederick, MD) on April 8, 2008 at 11:56 PM:

Jax! You're the one who posted that.. now I know!

I haven't heard of anybody else using capsules, but I've seen the little balls of clay + compost + seeds in several stores & catalogs now.

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Posted by Pamgarden (from Central, VA) on April 9, 2008 at 8:36 AM:

Well, I'm going to give it a try, probably with the clay, which is at hand. If I get to town in the next couple days, I'll get the polymer and go for the gel caps. Darn, I was just at the feed store yesterday. I'll bet they had both, but I was mesmerized by all the alfafa meal, gypsum, green soil, worm castings, and apple cider, and coconut oil. They were too busy for me to bother them about what the last two were for.

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Posted by critterologist (from Frederick, MD) on April 9, 2008 at 8:44 AM:

Hmm... after a long afternoon of digging in the wet spring garden, a mug of spiced cider and a nice massage (coconut oil) would be a treat!

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Posted by Jax4ever (from Boxford, MA) on April 9, 2008 at 7:24 PM:

A-men to the cider! Maybe a glass of wine for me!
I've sown 12 new flats of annuals since reading this: ipomea, cosmos, viola, torenia, sweet pea. I am going to sow some nasturiums tomorrow! It's supposed to be 70 out, so it isn't wintersown anymore!
I'm not using up my whole seed packets on the early sowing; I'm saving some of everything to direct-sow, too. It will be interesting to see how it all turns out!!!
Isn't Spring Optimism wonderful!? Check back with me in August, when I'm raging against the weeds and wishing 2 ft of snow would squash everything!!!

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Posted by critterologist (from Frederick, MD) on April 9, 2008 at 10:20 PM:

LOL... I like your optimism! The torenia will take a while to bloom, but I got blooms later on in summer from some volunteers last year. (And late blooming torenia are better than no torenia, in my book.)

:-)

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Posted by Jax4ever (from Boxford, MA) on April 10, 2008 at 12:33 PM:

There are so many seeds/plants that I gave up on and marked as failures simply b/c they didn't bloom early enough. Plants teach us many lessons, but maybe optimism, patience, and persistence are the best.

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