Gardening columnist

There is still a little time to turn your garden beds, make a narrow furrow and sprinkle a few seeds of some green or another.

Come December, lettuce varieties will handle several degrees of frost, and you can keep them going far longer with a little hoop tunnel and row covers. Hardier greens such as mustards, arugula, beet greens, mizuna and kale should furnish your plate through much of the winter, especially one like last year’s. You might think that if sowing seeds in March is merely poetic, in September it’s heroic. But my best lettuce of the season grows in the last three months of the year, when romaine and butterheads can fully develop without the stress of the summer heat.

Spring or fall, sowing seeds is a ritual steeped in optimism and forward thinking. There is something thrifty and honorable about it. But laying seed is also a process that begins with turning the garden bed, raking it smooth and aligning your rows — drills — so they are parallel and correctly spaced. Many gardeners fashion a drill guide from a string with a bamboo stick at each end. Water every two or three days, and, lo, the seedlings will emerge in the warm autumn soil in a week or less.

Then the work begins, because the key to raising healthy, robust greens is a technique called thinning. Plants need room; they need their own space for light and root nourishment. Without it they will be weak, leggy and, for bulbing plants such as onions, cabbages and radishes, reluctant to develop.

The way to allot space is quite simple but so often neglected because it’s fiddly and time-consuming. But it is straightforward. Say you sow a row of butterhead lettuce. When the seedlings are a couple of inches high, pull them so the remaining seedlings are at least an inch apart. The knack is not to disrupt the ones you are saving: You might even want to use scissors for culling.


Do this again when the leaves are up four inches, allowing a couple of inches between the keepers. At this point you can use the thinnings on sandwiches. Repeat as needed, as they say. A looseleaf lettuce should be spaced four to six inches from its neighbor. A heading lettuce will need eight inches or more to develop fully.

In November, when the upright romaine lettuces are getting beefy, I simply take every other one as needed to free space for what’s left.

I recently asked horticulturist Adam Cressman his view on thinning. He tends the demonstration vegetable garden at Longwood Gardens in Kennett Square, Pa.

“First, get your seeding rate perfectly,” he said. In other words, try to drop seeds evenly in the drill, about an inch apart. If you did this, that first thinning would be unnecessary. The difficulty is that the seeds are so small, they are hard to manipulate. Some are bulkier and easier: members of the cabbage family, or Swiss chard or, joy, peas and beans. But carrot and lettuce seeds are small and troublesome.

Cressman was saying, essentially: You can spend the time when you sow the seeds, or you can take even greater pains later by doing more thinning. The former is better for you and the plant, though in the midst of sowing 20 rows of lettuce the other day, I found this requires some focus and an ability to ignore the ants climbing up your arm.

You can pay a premium and buy tiny seeds encased in pellets for easier sowing, or even buy strips that are pre-seeded. Not my kind of gardening.

Cressman took me to a bed of carrot seedlings that cried out for thinning. “They say, ‘Three fingers for carrots,’ ” he said and then made his hand like a rabbit paw and grubbed out whole swaths of seedlings with his fingers. This is probably how they do it on a farm. I was searching for my smelling salts.

“Some people could spend hours in this area,” he said. That would be me.

Cressman grows about 50 different vegetables in this garden, totaling 120 varieties. His best tomato this year? He took me to a row where one was still productive, vigorous and remarkably leafy and green for so late in the season. “Mountain Magic,” he said. “It’s about the size of a golf ball, extremely productive and has very few defects,” he said. It will be on my list for next year.

He has also done well with sweet peppers, and he commends Orange Blaze, a small bell pepper that is both abundant and beautiful.

Soon the frost will end their days, but in a nearby bed, Cressman has fashioned two hoop tunnels, each from six lengths of electrical conduit. (He uses a pipe bender to get a perfect curve.) Beneath them, new seedlings of kale and spinach are growing. With plastic covers, vented on mild winter days, he will get a harvest through to February.

One garden season ends, another is just getting started.

@adrian_higgins on Twitter

Read past columns by Higgins.