A friend who is new to gardening asked about how to keep a supply of greens on hand into the winter. He’d been listening to a broadcast about self-sufficient early settlers and how they used cold frames for this purpose. Since we’ve just finished spreading manure and planting garlic, tucking it in for the winter under a blanket of hay, I can say quite honestly that I’m happy to be done thinking about gardening this year and already planning what I’ll do next year.

But in past years I’ve used coverings to extend the season. My first season of gardening in Maine, where temperatures seemed tropical compared to what I’d experienced in northern Vermont, we kept reseeding lettuces throughout the summer and by late October, which was still frost-free, they were flourishing. We erected a simple frame of lath and plastic over the greens, with a flap of plastic we could roll up and down to access them and regulate the temperature, and were still harvesting greens until mid-December, when a heavy snow collapsed the house and all the greens froze. It gave us a couple of months where we didn’t have to purchase salad greens and we felt quite pleased with ourselves. The key, of course, was that we’d continued replanting.

If you want to use a cold frame or even a plastic growing tunnel for winter growing, there are two different strategies. You can plant crops to harvest during the winter or you can start crops that will begin to grow in the fall, then remain in place until spring, when they will resume growth, allowing you an early spring harvest. You can even do both within the same tunnel or cold frame. For winter harvest of such crops as lettuces, spinach, arugula, or Asian greens, the goal is to seed your plants so that they’ve reached about 75-percent maturity by the time day length is less than ten hours. Right now, day length in Rockland is about 101⁄2 hours, so it’s very close to the time when plant growth ceases.

So for this fall you would have needed to sow a crop that is, say, 50 days to maturity back in late August. I’m allowing extra time here because days are already growing a bit shorter even then. It’s also a time when you’re harvesting and tending the rest of your garden, so it’s adding another chore to a busy season. Given the heat at the time, starting seedlings under some shade and frequent watering is also in order, and it can be tricky. One thing I’ve done is to not thin lettuces very well and take the smaller plants and transfer them into the cold frame, where they can mature later in the season. We’ve even done this with spinach, starting it in the garden, then transplanting it into a cold frame.

If you fill half of a cold frame with plants you intend to harvest in early winter, you can start seedlings in the other half for early spring harvest. Spinach, arugula and lettuces can be sown in mid- to late-September and nurtured along until they stop their growth, just about now. In Rockland, the first days of February are about 10 hours long, but by the end of the month the days have become about an hour and 15 minutes longer — plenty of sunshine to wake up those seedlings and get them growing.

I think the real question is this: Given the extra work of extending the season, is it worth the effort? Yes, if you factor in the delight you, as a gardener, feel when you step outside on a frosty morning, lift the cover on your cold frame, and harvest a fresh salad. On the other hand, we have options that our pioneering forefathers never dreamed of, among them the chance to purchase fresh greens produced locally and year-round by young farmers trying to make a living in Maine. In addition, if you have a root cellar or cold storage, you can have cabbages that last until March and can be finely shredded to make a salad base. Combine that base with some of those purchased greens or perhaps some shredded carrots and apples and thinly sliced red onion, also from the root cellar, and fresh sprouts you’ve raised in your kitchen, sprinkle in some windowsill herbs, toss in some toasted seeds or nuts, and you’ve got a good, crunchy, colorful salad for winter meals without needing a cold frame at all.