The germination will still occur, maybe at 50%.The problem is bugs.in the winter they look for anything to eat and I found its simply not worth it.Green onion is an exception as it grows quite well.If you have proper lights in the basement you could grow some stuff there ( parsley, cellery,cilantro,) etc.
When I grew stuff in the winter I could not use most of it.Between the rain, snow , bugs it was all alive but did not look too appetizing.The bugs will find their way under your plastic covers.They too like to stay protected.

Hi.

I've had good luck planting seeds of arugula, spinach, cilantro and most lettuces at this time of year. The plants last without protection until (some years, unless) we hit really cold weather here in the Puget Sound area. You must be in a similar zone in Vancouver, right? I think it is well worth a shot and shouldn't cost much, especially once our rains set in again.

Optimistically,

Rain

I have winter garden for quite a few years. I wouldn't worry about light. We seem to get enough to keep things going. A lot of the cole crops (kale, brussel sprouts, winter cabbage, year round cauliflower and broccoli), beetberry, spinach, radicchoio, and chard do really well in my garden wintering out.

Every few years a real cold snap might take out the radicchoio, cauliflower, broccoli and cabbage, but never the chard, kale or brussel sprouts. With your hoop house your should try lots of things. I have been thinking a cold frame would stretch my gardening for the green leafy plants. I find that the radicchoio, kale and brussel sprouts taste sweeter after frost. I only seem to be successful with the wintered over cauliflower.

Salt water soak is necessary for the brussel sprouts after harvesting and I have started trying different varieties with a look out for better resistance to leaf miners (esp. in chard). This is definitely a great area for year round growing in my experience.

Oh yeh, I just put out my last plantings of beetberry, spinach, mesclun, cauliflower and started my broad bean seeds for placing later in the beds where my corn, tomatoes, and squash are right now.

www.territorialseed.com have on online catalogue that will give you lots of ideas and were one of my resources when I first started year round gardening (they are based out of Oregon). I also use www.seedsofchange.com and that's were I ordered most of my seeds this year. www.mammothonion.co.uk is a British seed company that sends to the USA and I was able to get some broad beans and onion seeds that I couldn't find any where from US seed companies. Happy planting :)

Here is a link that might be useful: pics of Jewell's vegie garden