do you have some old windows plexiglass or similar which could be used to manufacture a small greenhouse? this could be a viable option. of course, you would probably need suggestions on how to vent it and to keep heat in it during the cold evening hour (or would sun generate enough heat?)

just a thought!

I'm not sure how warm-weather you're talking about, but you might want to check out the winter sowing forum here on garden web. Quite a few of us have seeds starting outside now, you just have to check on the zone ratings for the plant. Here's the link to the FAQ for the winter sowing forum, which has lists of perennials that you can winter sow....
faq.gardenweb.com/faq/wtrsow/

I follow this wintersown schedule, see if it might be right for you:

after dec. 21/mid Feburary - perennials/shrubs from seed, the only exception are buckeyes which need to stay moist so they go in as soon as the seed is ready
Mid-Feb-mid March - cold hardy vegetables such as collards, kales and anything frost tolerant, johnny jump ups, nasturtiums, calendula and other cool weather annuals - stuff I could throw a sheet over if we get a light frost
April 1st - 15th I check to see how the weather is going and will start my warm weather vegetables
Everything is done outside.
We all have microclimates in our yards so that is not hard or fast rules of dates, plus weather changes from year to year. Just my own guidelines and I am late myself!!!

Thanks, everyone. Girlgroupgirl, when you sow perennials by seed this way, how large do they get by the end of a growing season? Will something like a coneflower or a butterfly weed bloom that first year?

My budget is battling my impatience.

Coneflower blooms 2nd year - yellow and orange milkweed bloom 1st year and can be annual or short lived perennial depending on winter weather. Other perennial milkweeds bloom 2nd year for me.
Most perennials will bloom 2nd year - I only grow unusual perennials from seed now and just bite the bullet and buy/trade anything else so I don't have to wait.

GGG