I have had a request for How-To "Wintersow" Instructions. This is a method using milk-jugs, which I find the easiest.

Timing: I find Mid March a good time for a couple of reasons. We typically don't get hit with extreme cold temperatures and the days are longer - works best with 12+ hour daylight

What can be wintersowed: Any perennials hardy to your zone, all seeds that require stratification (pre-chill) and also any seeds that the seed package states direct sow "x" number of weeks before last frost and/or "early spring", "as soon as the ground can be worked" or "late fall". (note: ignore the suggested number of weeks before last frost). At the end of May your ws seedlings may look small, but by mid to late June they will really bolt.

Do not wintersow: Tropicals and expensive seeds that take 12 weeks to bloom from germination. You will be disappointed.

Perks: Low maintenance. Do do not have to worry about lights, germination temperatures, damping off, hardening off and for the most part Mother Nature will also take care of moisture, but do check that they do not dry out and become parched.

PREPARING THE CONTAINER

1. Clean the milk jug (throw out the cap). I add bleach to the soapy water to disinfect.
2. Put at least 5 drain holes in the bottom of the jug. I use a 1/2" drill bit on a cordless tool
3. Slice venting holes along the neck of the jug
4. Cut the jug in half, leaving a "hinge"

See photo:

5. Put at least 3" "pre-moistened" potting soil and sow seeds to the recommended depth
6. LABEL your jug with a paint pen or industrial permanent marker (regular sharpy permanent marker will fade). Be sure to include the variety of the seeds that you sowed. You may want to put the date sown as well.
7. Tape the jug closed (around the middle) and set outside in a sheltered sunny area.

Pile the snow on them. The seeds will germinate when the conditions are right for them, but it will be several weeks sooner then if you direct sowed them. The milk jug acts like a little greenhouse.

*Don't forget to check them periodically for moisture level. You don't want them to dry out and become parched.

Set them out side. Photo taken March 9th

Same jugs on March 30

Same jugs April 5th. Not everything will germinate at the same time of course. And if you keep them watered when it get warm, you can take your time to plant them out into the garden. The only jug that I lost was one of alyssum. We had an unusual cold snap for a few days the 3rd week in April and the alyssum had been up for a few weeks. The temps drops to -20ºC, which is -4ºF. It was too cold for those seedlings. The alyssum was the only one out of the 69 jugs.

Your new plants will be tough and give you lots of blooms

Fill your yard with colour

I've only wintersowed for a few years. There are a number of our cubit members that have quite a bit of experience with wintersowing, so please chime in with some tips.

Boy, you can't go wrong if you follow Joanne's excellent instructions!

Just a small addition: Make sure that your milk jug or other container lets some light through. Around here our less-expensive supermarket milk is the Hoods brand, the jugs of which are totally white and definitely too opaque. Joanne's milk jugs in her photos are the right type. You should be able to see the shadow of your finger inside when light shines through. For my Hoods jugs, I cut out the sides and just place a clear plastic gallon-sized zip-lock baggie (vented) over the top but it's much more cutting to do and a pain.

Also, if you wish to reuse your milk jugs for next year's wintersowing, rather than writing on them you can place a plastic plant marker inside with all the plant particulars written on it. But I generally just start over each year because I end up with so many recycled milk jugs!

Thanks for the fantastic instructions! Joanna can you do petunia seeds?

Sure, petunias will wintersow. BUT the some seeds are expensive and do realize that most petunias take 8 to 12 weeks to bloom from sprout stage. Also, with petunias, many varieties are daylight sensitive to forming buds, so if they start blooming in August, they will wind down quickly as the days get shorter.

Petunias would not be a ws choice for me, but to each their own.

Makes sense....thanks!

I've had great results wintersowing petunias. They sprout pretty early (low temps) and tolerate a light to moderate frost just fine. I've had them start blooming in June. As Joanne mentioned, some are daylight sensitive.

Laura Bush are the toughest I've ever seen. And they reseed a lot!!! If you wintersow them once they'll probably come back forever. Last year the LB volunteers kept eating my echinacea. I had to yank petunias frequently. I do love these though.

Karen

Karen your echinacea are gorgeous!

Thanks, Donna. I like that one, too.

Karen

Do you remember what the name is? Luv pinks!

That one is Pink Double Delight.

Karen

Ooooh..I'm going to have to find some seeds.

Donna, it's a newer, hybrid variety. It's reproduced vegetatively, not from seed. Seeds from most hybrids don't produce the same plant. It might be similar or might be totally different. Or, some are sterile and don't produce seeds at all. To get this same plant you have to buy it or get a division from someone.

Karen

Oh...I didn't know that. I'll check a couple of catalogs to see if they carry it.