Last year I did sow directly into my large urns on my front porch. I had some clear plastic from an old cheapo frame. I sued it to cover the pots.

This year I sowed my alyssum seeds directly in with no cover. I threw away the plastic ones. They kept blowing off.

Also my pots were too big for those large hefty bags to go over. Those might be ok for you. (see link)

If those bags are big enough you can put all the way around the container. I did that a couple years ago with a medium size pot.

http://www.amazon.com/Hefty-One-Zip-Big-Pack/dp/B0032C6FB6/ref=sr_1_2?ie=UTF8&qid=1301360577&sr=8-2

Here is a link that might be useful: Hefty-One-Zip-Big-Pack/

mary_max

I like the idea of using wider pots to plant your seeds that way you can plant many seeds without havibg to thin them too much. did you have holes in the plastic? Also how would you water them especially if you duct taped them. It is not practicle to remove duct everytime you water them. is it?

could you make some sort of a tepe,say, with bamboo, and plastic,closed with clothes pins,that way, you could open it,and close it when you need to.

I use clothespins and/or staples to keep plastic over large pots. Easy to remove and replace for watering. Wire hangers with the cardboard off the bottom can be used to prop the plastic up.

Another idea is to sow seeds and put a 2L or jug with the bottom cut off over the seeds. This works really well when I plant several different kinds of seeds in one pot.

I sowed peas and spinach directly into large containers earlier this month. After planting, I watered the soil and put a piece of plastic wrap directly on top of the potting mix to keep it moist until the seeds germinated. The plastic held the moisture in well, and the seeds germinated quchkly and well. When the sprouts showed, I removed the sheet of plastic from the soil and let the plants grow as usual. The one thing I noted, was that on sunny days, the plastic seemed to help the potting mix warm.

The struggle this year has been to keep the young plants from freezing. I've covered the containers with quilt batting each evening for five nights now. It's about time for the weather to warm up, IMHO.

"After planting, I watered the soil and put a piece of plastic wrap directly on top of the potting mix to keep it moist until the seeds germinated. The plastic held the moisture in well, and the seeds germinated quchkly and well."

Does this mean seeds do not require air circulation to germinate? Did you have any holes in the plastic wrap ?

I'm not sure where I picked up the idea of putting plastic wrap on top of freshly planted potting mix. I'm sure I read it somewhere. I've also heard of using a board in the same way to keep potting mix moist until the seeds sprout. I can't speak to whether the seed needs air to germinate. I only know this method worked for me. I can say that the plastic wrap didn't cover all of the soil. There were open spaces at the edge of the container. Whether that matters, I don't know.

When I wintersow in big containers, I use press and seal, pushing two sheets together before wrapping them over the top, leaving at least a few inches over the edges. I "press to seal" around the top and all around the pot (pot must be dry) and then I tie a piece of string (whatever I had handy including a couple of old shoe laces tied together) around the edge. A bungy cord works too. Then I punch a couple of vent holes in the top. Once it starts getting warm, I can easily widen the vent holes or pull the bow on the string open and lift an edge of the press and seal if it is early and I think I could need to close back up.

Actually I use press and seal on my plastic cup wintersowing too, if I don't have clear plastic lids to fit. But then I cut the press and seal into squares and use a wide rubber band to secure (the skinny ones can't stand up to weather).

If you don't fill the container all the way to the top with soil, there will be head room between the plastic top and the seeds.