As I write this, I’m anticipating Thanksgiving dinner. Two of them in three days, actually, that I’ll be hosting. Two 20-pound heritage birds plus a bacon-wrapped turkey breast for my brothers, 30 pounds of local root vegetables, six stalks-worth of Brussels sprouts, four pans of sausage and apple stuffing, six pies, two pumpkin rolls and a chocolate cake later, I know I’ll need a couple of salads to set things calorically right.

Lucky for us gluttons, finding local lettuce as winter tightens its grip on Maine’s food supply is easier than it used to be thanks to the growing number of hydroponic operations cropping up around the state.

Yes, many Maine soil-based farmers extend their leafy greens growing season via hoops houses and high tunnels until the bitterest of the cold arrives. Sustaining their efforts means buying their products early and often as supplies last.

But hydroponic systems can yield fresh produce 365 days a year because they aren’t rooted in cold, hard soil. Seeds are germinated in anorganic (not living) substrates like coco coir (pellets made from coconut husks) or peat moss. The crops – high value ones like herbs, cucumber, lettuce and tomatoes that offset infrastructure investments quickly – mature in temperate greenhouses. Their roots sit in nutrient-rich water in these closed systems, which use up to 95 percent less water than traditional farming in soil does.

Sometimes fish, tilapia mostly, swim in adjacent tanks. Their waste is turned into fertilizer that is introduced to the water flow. Such systems are known as aquaponic.

A worker at Olivia’s Garden in New Gloucester transplants hydroponically grown basil. Hydroponics are not new to Maine, which boasts a number of the operations – so finding locally grown vegetables is possible even as winter nears.

Hydroponics are not new in Maine. In Blue Hill, Court Haight has been growing lettuce and tomatoes chemical- and pesticide-free using the hydroponics systems he rigged up 25 years ago. He sells the produce himself at several farmers markets. Olivia’s Garden started growing tomatoes hydroponically in 1997 and has expanded to grow basil, cucumbers, edible flowers, lettuce and microgreens inside its 19,000-square-foot facility in New Gloucester. Madison-based Backyard Farms, started in 2007, is now a big name in year-round tomato production throughout New England.

What has changed is demand. More eaters understand that buying Maine leafy greens is markedly more sustainable than trucking them in from California. Hydroponics lets producers bring local greens to market consistently and reliably any time of year.

Additionally, as the industry making the hydroponics gear expands to support legalized marijuana production, the prices and energy requirements of the technology go down.

Springworks Farm erected its 6,000-square-foot aquaponics operation in 2014 in Lisbon. Founder and Bowdoin College student Trevor Kenkel says annual production tops 250,000 heads of lettuce – bibb, baby romaine and red and green leaf. Each costs $2.50 to $3, and they are sold to chefs, local natural foods stores like Royal River Natural Foods in Freeport, Bath Natural Market and select Hannaford stores. Fifteen hundred tilapia swim in 1,200-gallon tanks until they weigh about 3 pounds. The mature fish are sold to Harbor Fish Market in Portland and replaced with fish fingerlings.

Salad made with lettuce grown aquaponically and hydroponically.

The lighting is time-controlled to minimize energy use and a thermal water tank helps keep the greenhouse warm enough for the plants to thrive. The operation has been certified organic by Organic Certifiers Inc. in California. Springworks’ greens are harvested from their floating rafts in late afternoon for early morning delivery the following day.

“The short turnaround of local distribution eliminates a lot of potential food waste,” Kenkel said, adding that as much as 40 percent of the organic lettuce distributed nationally rots before it hits the plate.

But farmers and others debate whether hydroponics systems can be categorized as organic. The USDA’s regulations are fuzzy about them at best, explains Maine Organic Farmers and Gardeners Association’s (MOFGA) crop specialist Eric Sideman. Some third party outfits like Organic Certifiers Inc. will certify hydroponic systems based on the types of inputs used in the operation. Other organizations, like MOFGA, argues that an organic operation must involve soil, ergo it won’t certify hydroponic systems.

“Hydroponic production can be a very good, clean, green, pesticide-free means of growing food,” Sideman said. “But organic farming was founded on the principle of protecting the soil, regenerating it, as you farm it. So certifying that soil-less operations can be organic goes against the point. Feed the soil, not the crop.

Kenkel disagrees. “We treat our farm as a whole ecosystem and don’t use chemical fertilizers or pesticides,” he said, adding that organic certification should be dynamic enough to encompass other sustainable farming techniques that produce healthy, safe, clean food.

Chew on that while you enjoy your salad.

Christine Burns Rudalevige is a food writer, recipe developer and tester and cooking teacher in Brunswick, and the author of “Green Plate Special,” a new cookbook from Islandport based on these columns. She can be contacted at cburns1227@gmail.com.

BUTTERY BIBB LETTUCE WITH MUSTARD VINAIGRETTE AND HERBS

In the first weeks of culinary school I partnered with one of the only other students in the room who was old enough to drink legally. His name was Gene, a former U.S. Marine retraining to be a chef. He insisted on doing all the whisking when we made things like mayonnaise or salad dressings. Fine by me, I haven’t the patience and endurance to whisk drops of oil, one at a time into vinegar and mustard so that the suspension holds. I am not sure where Gene is now, so I use a blender.

Serves 2-4 (with 3/4 cups leftover dressing)

2 tablespoons Dijon mustard

1/4 cup red wine vinegar

3/4 cup neutral oil (safflower, grapeseed, canola)

1 tablespoon minced shallot

2 heads of bibb lettuce, washed and torn

2 tablespoons minced parsley

2 tablespoons minced tarragon

1 tablespoon minced chives

Salt and pepper to taste

Combine the mustard and vinegar in a blender. Turn the machine on to a medium speed. With it still running, very slowly add the oil. The mixture will emulsify and become creamy. Pour 1/4 of the dressing into the bottom of a large salad bowl. Add the shallots and torn lettuce. Toss well. Sprinkle the minced herbs, salt and pepper over the lettuce and toss well once more. Serve immediately.

Store the remaining vinaigrette in an airtight container at room temperature for up to a week.