great topic Chris. I definitely relate, I am in a similar 5b/6a climate. Love Fukuoka, just wish my climate was a bit more friendly like coastal Japan. Here are a few things that have seemed to work for me over the years-
Winter snow, for me, is its own season. It is a giant pause button for the garden. It is a season of soil fertility regeneration. I think in its own way, the winter snow cover is an asset to what I do in the garden. Bare dirt and freezing temps seems much scarier for the long term crop cycles. We are generally blanketed in snow for three months, December, January, and February. I try to lay down some sort of
compost mulch at Thanksgiving, which is metabolized into the soil in a magical way by the time the snows melt.
Spinach, carrots, garlic, parsely all work very well when sown in the late late Fall, just before the snows come. Generally between Thanksgiving and December 1st for me. They germinate in the spring, mid March to early April. Spinach harvests all through June. Carrots harvest all through July. Garlic harvests mid to late July. If I sow these earlier in the fall and they germinate in the fall, they will either die over winter or bolt instantly in the spring. Putting the seeds in the ground December 1st, and letting nature decide when to sprout works really well.
I have found that all the umbels (carrot, celery, parsely, etc) and the chenopods (beets, spinach, chard, etc) do not rot in the soil, and germinate reliably in spring. Nightshades also do not rot (tomato, pepper, etc) but I generally dont try to grow them Fukuoka style because there is such a heavy covering of weeds before these guys germinate in May. Brassicas (kale, cabbage, etc), alliums (onions), cucurbits (squash, cukes, etc), and beans all rot in the soil over winter and do not work, IMHE.
Winter wheat works best sown in mid October, so that it just germinates and then gets buried in snow. The plants emerge in spring with great vigor, and mature in mid July.
Once we get to mid April, our climate is like a temperate climate anywhere, just a bit cooler. From April to October, I have found the key to be sequencing crops so that I sow something, and then transplant another crop into the sown bed. There are exceptions, but I try to keep sowing or transplanting new crops into existing beds throughout the season to keep a continuous cover of vegetables going. Some of my favorite sequences are cabbage transplants > carrot sowing > fall spinach. Also carrot sowing > zucchini sowing > fall turnips. Also radish and
pea sowing > rutabega and potato sowing > fall lettuce. And turnip sowing > cucumber and green bean sowing > fall beets. You get the idea.
November is the dead month in the garden. There is tons of mulch litter from the season's growth. The climate is way too cold to really grow anything. So I give the garden to the calves and the
chickens. I mulch heavily with compost. The soil dries out and I rotary plow any areas that are hopeless with weeds. With the first indications of winter's snows towards the end of the month, the cycle begins anew.
In the future I hope to sow more clover type cover crops in December as well. So that in the spring, the entire garden blooms with seeds I have planted. Right now, I have about half the garden planted before the snows melt. The other half rests mostly bare through April as I wait for the soil to warm up
enough for warm season crops. I can shallowly cultivate (not till) during April, which helps a lot with weeds down the line in the summer. The bare soil also warms much faster than it would if it were covered in vegetation. So there are some okay aspects to the system. But I think that as I reduce the load of weed seeds in the garden, and introduce more
raised bed contours, that overwintering cover crop seeds for fertility enrichment will be a good strategy.
Glad you brought up the topic! I felt really stumped for years by Fukuoka's moderate and moist climate. But now I realize that with a few tweaks, we can acheive similar successes in our much colder Northern gardens.
hope that helped-