A. You could do both. For the fall and winter months, consider planting a “cover crop” of either annual ryegrass or white Dutch clover. Planted now, those two crops have plenty of time to germinate and settle before true winter. Then next year in late winter – four weeks before you’d start to plant in the garden, turn the winter crop under to a depth of 8 to 12 inches, and you’ll add what’s called green manure to the soil. As it decomposes, it feeds the soil, adding nutrition to whatever you choose to grow in the garden. If you decide to plant a cover crop, you’ll need to continue to water those areas regularly until it germinates and starts to look like it’s taken hold. It should look and act like a green carpet. It’ll need water all through the winter, too. Also, by growing a cover crop, you’ll be less likely to have two extra things to think about.
First, there won’t be as many weeds to contend with next year, since the green carpet effectively denies any weed seed from lying in wait in your gardens. Second, because the soil is “covered,” it won’t be as likely to dry up and blow away. Cover crops are a good thing to do for your garden soil.
If planting a cover crop doesn’t sound like something you’d want to do, then at least get into the habit of watering the area and turning the soil to a depth of 8 inches monthly. That’ll keep the soil oxygenated, break up any clumpy spots and bring soil-borne pests to the surface so they would be more likely to succumb to the weather or be successfully hunted by birds.
Then, by late winter, the end of February to early March, spread a stout layer of manure and/or mushroom compost, worm castings and a slow-release fertilizer and turn it under. Do this at least three weeks before you plant, and be sure to water a few times, too, so the nutrition gets spread out more evenly.
On an older airing of “This Old House” I watched recently, they planted lots of daffodil bulbs in raised beds in the fall so that by the time they were finished blooming in the spring you’d get a visual reminder that veggie planting time had arrived. Because the area contained bulbs, you’d be less likely to forget watering during the winter months. Know too that bulbs planted below a cover crop would work also. You’d just turn a little bit later in the season that’s all. So truly, both seasons are good times to get and keep the garden soil healthy. The more you do for it and add to it the healthier it’ll become.