Lol. Just saw that this same question had been posed several days ago. Sorry for the similar post. If anyone has anything else to add, or any alternative containers that have worked well for you, it’s appreciated. Thanks :)

'Winter sowing' is just a new label that has been given to the age old practice of sowing in ordinary pots in autumn. If you don't have a cloche, cold frame or sheet of glass cover the pots with chicken wire to keep animals and birds out. A layer of grit over the pots is useful.

But Floral, your suggested methods don't have an opening for water. The beauty of wintersowing as I understand it is that you can put out the open jugs (with drainage of course) and just ignore them til seedlings appear.

Open pots under chicken wire can be watered. Otherwise just open the lid of the cloche or whatever. But honestly, in winter watering Is rarely necessary. Certainly not in my climate. You can ignore the sowings just as if they were under plastic bottles.

I lived in 6b many years ago, and wsing in open pots worked fine because the temperature fluctuations were more gradual. I'm in 8b now, and can't ws without some sort of cover. It really just depends on how your weather behaves. if it gets super warm and then hard freezes, the covers mitigate or support the weight of further protection (like a blanket during a freak record weather event) from hard freezes over seedlings that are thickly touching the container sides.

If your temps increase reasonably moderately, no cover is required. Maybe wire and grit to block birds and insects, in case they plague you. If your temps are wild swings, then windows, or any plastic bag fastened around the pot, etc. might be needed.

I'm with you on difficulty in finding easy set and forget containers. What has worked best for me are 2 liter soda bottles, with the caps off, only 5 holes in the bottom for drainage, no yearly destruction. So I can keep them from year to year. Also no fussing about water. It rains enough here in the winter that the cap opening allows plenty of water in.

If you try that, I'd hang onto the caps maybe for excessive freezes without snow. I have to corral my 2 liters in something to keep them from blowing across the landscape, but may not be needed depending on your winds.

Milk/water jugs don't last as many years, even with care, and takeaway or salad containers are usually shattering by next season when removing from storage. The difficulty is finding someone who is willing to let you have these plastic containers in the first place.

I've never done that gradual destruction of the container idea either, when this concept gained a more methodical popularity years ago. It's never been needed. Just plant them out when it's safe, or before they bust the container themselves. I suppose I never had excess containers to waste either.

I keep messing around with cold frame designs to find a more permanant, scalable solution than jugs and bottles. I don't think of hard sudden freezes as a problem, but maybe it is for some species. The down pours that make a compacted block out of the soil and flood open containers are a concern here. 50,000,000 maple samaras and weed seeds, and slugs, are the other problems I've run into.

I have come up with a couple tunnel-type coldframe designs, but eventually will move on to a wood frame, screened sides, and a polycarbonate panel roof. A clear/translucent patio table with insect netting draped over it would make an excellent impromptu coldframe for open containers.

Oh wow, yes, the great bird seed swap! I forgot how bad that used to be. Slugs are a menace, but a cold frame has never stopped them for me? They just come right on in, from the bottom. I get less damage from slugs/snails these days too, now that I'm mostly using 2 liters.

Larger openings and such on other cobbled together containers ended up full of snails. Less damage, if they mostly were trying to get in through lower drainage holes. Getting a good quantity of 2 liters was a long weird process though. I mean you're basically asking someone to give up what to them is their personal trash.

Cold frames are frustrating with the high maintenance of watering during the rainy season where I don't want to haul water around? Maybe I'm going about it wrong. Received a lovely acrylic one as a gift, that auto opens in heat, and it still has to have the lids lifted to water. None of them seem to allow water in easily. Plus the seedlings are very vulnerable, because of insects coming up through any ground access, namely fire ants.

I can't imagine trying to direct seed into it. The seeds would simply end up as snacks unless individually well wrapped in something the decomposes slowly. (Which has been a successful way to direct sow bigger seeds, but only in season.)

Admittedly I don't sow flowers and such. Flowers are just too difficult. I sow fruiting tree/bush seeds or cuttings, and herbs/veggies. The veggies are the delicate things for me during crazy freezes, and I have to grow most of the cool weather veggies/herbs in winter as our fall and spring are too hot. Not all of the veggies have problems of course. Just the ones I only had a few seeds left, can't find the variety anymore, and the reasonably viable set of seeds are 9 years old. Normally I save seeds, so series of events gone wrong there. lol

Don't think I've ever had a perennial seedling take more than cosmetic damage from a crazy freeze, even outside exposed. If any bothered to really come up in winter. The mini-greenhouse doesn't seem to change their behavior all that much. They come up when they come up, and don't grow too thick above ground in winter. Mostly they work on roots. They will take full on damage from random dogs, opossums, and other bull-in-china-shop wildlife. However, no container I've seen is protection from that. But usually lighter to move into a protective corral.