Winter Garden Quandaries and Garden Planning

Hello, it's me, resurfacing after another busy week! I've just been out for my weekly survey of the garden, and I finally managed to convince myself that the kale I planted several weeks ago simply wasn't going to sprout. It was Dwarf Scotch Kale and very cold hardy, so I'm not entirely sure why it decided to be inactive, but the seed was about two years old so possibly it had gone bad. It's disappointing, because we love kale and are both craving greens and vitamins now that the days are so short and the darkness is so long. The spinach and radishes I planted around the same time were growing strongly, though slowly, and I'm out of radish seed so I decided to replant the areas of kale with spinach.

(Click on Photos to Enlarge)

Spinach (left) and radishes last weekend. 

This is the first time I've ever really tried to grow crops through the winter in Portland. The summer was so chaotic that I didn't manage to sit down and plan out crop rotations or really learn what I should about winter gardening, so it's kind of by the seat of the pants this year. Does anyone in a similar climate have any advice on what/how to grow during the winter? Portland is in hardiness zone 7. Between October and March it rains pretty consistently and high temperatures hover between 45 and 50 F (7-10C). It rarely snows, but we usually get a couple really cold snaps right around the new year.

I'm really looking forward to sitting down over my winter break and spending a good long time on seed ordering and garden planning, reading up and learning more of the specifics of timing and soil composition, that kind of thing. A month from now I'll be on vacation from school for four weeks, and apart from putting together some holiday gifts, garden planning for the next year is my #1 priority. I usually end up starting things like tomatoes and peppers inside in early March, so I need to get down to business soon. 

Most of the garden is in cover crops this year, all of which are growing really well:

 Austrian (field) peas. 

Field peas and fava beans fighting it out with weeds in one bed. This was taken last week, they're definitely winning out this week!

I took these pictures just this afternoon, looking toward the garden and backyard from the kitchen windows:

 The Asian Pear tree on the right is finally dropping its leaves, but the apples seem determined to keep theirs. 

The garden beds. You can see the freshly tilled patches that I planted in spinach today. I don't know if these photos convey just how cold and dark it is at 2 pm on a November afternoon in Portland. After daylight savings last week, it now gets completely dark just after 5 pm.

Anyone have advice or stories about winter gardening? I'd love to hear about your experiences!