It is possible you aren't doing anything wrong. You may just need to wait. I haven't grown all the things you mention, but in my experience marigolds and many squashes need a little bit of warmer weather before they germinate. Don't give up. Just wait.

Setting aside the issue of "cheap" potting soil, are you keeping your containers evenly moist, yet well drained?

I also would start with your drainage. I put holes about the same size as a pot would have and cover them with a small piece of screen the water drains out very quick but the containers stay real moist until I start making the air holes bigger for my sprouts. Even once I start making the air holes bigger the container still doesn't need water for a while, usually a week or longer. I thought that Morning Glories were one of the easier plants to WS. Mine were sowed on 4/19, came up in just 5 days and today I had to take the top off of the container. Yet as mentioned above I'm in a warmer area than u, so maybe you're just not waiting long enough. My peppers took much longer and my Sweet Peas still haven't sprouted. Keep trying and best of luck.

Strouper

Morning Glories- I wouldn't do them in January, February, or March. I will be getting mine out in the next few days, which is about a month earlier than I did them last year with great results.
Marigolds- some claim they reseed, but I've never had them do so. I do them in Mid-March.
Squash- don't know anything about that, but never start my veggies til about now anyway.
Petunias may have gotten too wet. I lost a lot of mine in a mud-bowl last year. Sowed them in Mid-march this time, and nearly all are up.

For the record, as a general rule of my own thumb, I put about 2 weeks between zones. Ie: If Zone 6 is starting something Mid-February, I'll wait til early March. If they are in Zone 7, I'll wait 4 weeks to do the same thing here in Zone 5. So far, this has worked well for me.

Gabrielle,
The first thing I have to ask is would you "define 'cheap potting soil'"?
I've used Schultz, Miracle Gro (just the regular potting soil with no extras), a grower's mix similar to ProMix that I can get locally, and finally, Promix. All of them worked like a charm for me.
So knowing what you used might help in the evaluation. The soil is the base of the whole production. Bad potting soil will definitely produce bad results.

Linda

Sounds like weather may be your biggest culprit. It's been crazy this year and temps have not been warm enough to germinate your seeds.

I'm in zone 5 MA on the New Hampshire border. Just have one pumking seed up out of 10 so far and not worried about it. My temps keep going from warm to cool, to cold. Temps in high 30's to low 40's still at night. some days have warmed up to the 60's and low 70's, but temps at night still cool. Lots of rain too. Soil needs to warm up as well as the temps.

Try moving the containers into the direct sun, should help the germination.

How compacted is the soil? what kind of soil are you using, ie brand. that could be the problem as well.

Fran

I experimented a little and used Dollar General's potting soil in the $2 bag for some of my WSing. Got some damping off. I think it was just one bag, but I was diappointed to lose the seedlings.

Good soil, drainage and start your seeds later. All those you mentioned do not need cold period so if you start them too early and drainage is not good they will rot.

Marigold not reseeding?? I always have millions of seeds and many volunteers from the past five years. I try to keep up with deadheading because they can get all over the place.

You can carefully dig around in your pots to find the seeds you planted and see if they rotted. If they did, you might try changing the way you place your squash and pumpkin seeds in the soil. Instead of placing them flat in the soil, stand them on edge. This will help keep them from rotting. Just don't plant them with the pointed ends pointing up and down. If you find roots on the seeds you planted, just gently put them back where you found them.

The other thing is, do you know if your seeds sprouted during any of the warm spells we had during the winter? (Or maybe you didn't have that problem in MN?) If so, they may have been killed when winter returned. Maybe they started to root and then froze before you ever saw sprouts. Squash and pumpkin seeds happily survive in the soil all winter long in New England, but if they sprout before the weather stabilizes, they can either be in for a rude shock or sudden death.

Gabrielle,
Another thing I thought of was the containers you used.
Your zone is colder than mine and I had poor germination my first year from anything I put out in January in a container other than a juice jug or milk jug.
I can't explain why, but I just think the seeds and soil needed extra protection from our cold weather.

But I still think the soil might be the biggest culprit.

Linda

Come to think about it, Walmart and Target didn't have potting soil in February here, so the potting soil I bought this year was the store brand from a local nursery. Not the cheapest stuff on the market, but the cheapest I could find at the time.

Yep, I use the plastic milk JUGS, not cartons.

Warm spells like circal825 mentioned do happen here, but not this year.

Boy, starting the seeds later seems to really take the "winter" out of "winter sowing". I'll try giving them some more time to sprout, if not I'll dig in the soil to see if they rotted.

I was surprised when I couldn't get the marigolds to come up, too! I get all sorts of volunteers in the garden, but I couldn't get them to WS. What the -- ??

Thank you so much for all the advice! I'll try again next year!

With the exception of petunia, none of those seeds are ones I would winter sow down here in zone 6. All I would late winter sow or summer sow because of our moderate springs. Marigolds and ipomoeas I start later because of their propersity to sprout at the slightest warm spell and then die at our wildly swinging cold snaps. I hold off of squash because of its propensity to rot here. I don't know what is going on in your area, but that's my experience here.

I use WS for perennials and annuals and not vine veggies. But I do love Wsing Toms. That's just my experience.

Gabrielle,
It seems they don't carry potting soil around here in February either, so one year, I actually wound up buying soil online! (my poor mail lady).
Last year I bought some during late summer and kept it indoors in a back room so I would have it in the winter when I started sowing. It carried me through until the end of March and by then, places were starting to stock it again.
So buy some this summer and keep a stash if you can. I sometimes empty the bag into several cat litter buckets and stack them, just so they are neater and easier to store out of the way.

Linda