Edible Landscaping - How to: Grow Greens Indoors

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By Charlie Nardozzi

You can have fresh lettuce all winter by growing plants indoors.

Start greens from seed planted in trays grown under artificial lights.

It may dark and chilly in November in most parts of the country, but a true gardener will always find a way to keep growing plants, even under adverse conditions. Gardeners in warm climates are enjoying the fall planting and harvest season, while gardeners in cold climates still continue to harvest winter hardy vegetables such as kale, carrots, leeks and Brussels sprouts. These will survive temperatures in the 20 degree F range with some winter protection.

But if you crave delicate salad greens and don't live where you can grow them outdoors in winter, or you live in an apartment with little room to garden outdoors, there's another option. The solution is indoor gardening under lights. By using an artificial light setup and growing plants in pots or containers, you can harvest lettuce, spinach and other greens right through the winter instead of paying through the nose for these salad greens at the grocery store. All it takes is a little preparation to grow your own salad garden this winter. Here's how:

  1. Purchase a lighting system for growing greens indoors. It's best to have a 2 or 4 fluorescent bulb fixture with a mix of cool white and warm white bulbs. You can also purchase grow lights or the newer T-5 lights. Though more expensive than other fluorescent lights, T-5 lights are skinnier than regular fluorescent bulbs, use less energy, last longer and deliver more of the light spectrum plants need to grow. Replace fluorescent bulbs when they turn black at the ends. The black color indicates the light output has greatly diminished.
  2. Choose greens that are adapted to indoor growing. Loose leaf lettuce varieties, such as 'Black Seeded Simpson' and 'Tom Thumb', baby spinach varieties, such as 'Catalina', arugula and mesclun mix are some good choices. You can even experiment with growing radishes, Asian greens and broccoli as micro-greens, or grow herbs indoors. See the links at the end of this article for more information on these crops.
  3. For containers, use plastic pots, seed trays or even the clear plastic containers in which lettuce is sold at grocery stores. If using recycled plastic containers such as the lettuce containers, be sure there are plenty of drainage holes in the bottom.
  4. Micro-greens are vegetable seedlings that are picked very young. You can use a variety of vegetables for micro-greens, such as radish, broccoli, and bok choi.

    Grow your indoor salad garden so the lights are about 6 inches above the tops of the plants. If the lights are too far away the plants will get leggy. Too close and the lights may burn the leaves.

  5. Add moistened soilless potting soil or seed starting mix to the pots and trays so it's about 3 to 4-inches deep.
  6. Sow seeds 1/2 to 1inch apart in rows in the trays, or sow a few seeds per small pot. Some lettuce varieties need light to germinate, so barely cover the seeds with potting soil and mist with water.
  7. Cover the trays and pots with a black plastic bag and place them in a warm (70F) spot. Often the top of the refrigerator is a good place to hasten germination since it stays consistently warm.
  8. Check the pots and trays daily. Once the seeds begin to germinate, remove the plastic bag and place the seedlings under lights.
  9. Position the lights just above the growing seedlings. Using a timer, keep the lights on during the day for 14 hours/day.
  10. Move the lights up as the seedlings grow, keeping them about 6-inches from the top of the plants. If you place your hand on top of the greens and it's warm, then the bulb is too close and may burn the tender foliage.
  11. If you're growing lettuce, spinach and mesclun mix for baby greens, begin to harvest when they are 4-inches tall (20-30 days after seeding), cutting them with a scissors one inch above the soil. Allow the greens to grow back again for a second and even third harvest.
  12. If you're growing lettuce and spinach into larger heads, transplant individual seedlings into 4 to 6-inch diameter pots. Let them grow to full size (45-60 days), then remove the entire plant when harvesting.
  13. Keep the pots watered and fertilize weekly with a dilute organic fertilizer. While fish emulsion is a great organic fertilizer for greens, be aware if you use fish emulsion indoors, the smell will permeate the house. Consider other organic fertilizer options if that's a concern.
  14. Once you harvest the large heads of lettuce and spinach, or the baby greens begin to get tough and woody, compost the plants and potting soil and start over again. You can repeat sowing a greens garden 2 to 3 times in winter to have a continual salad crop. You can even time your greens garden to be in full harvest for the holidays or a special birthday. Imagine a celebration featuring greens grown indoors in your house.
Other indoor greens growing stories:

Micro-greens are Big
Growing Herbs Indoors
And What Color is Your Lettuce?

About Charlie Nardozzi
Thumb of 2020-06-04/Trish/0723fdCharlie Nardozzi is an award winning, nationally recognized garden writer, speaker, radio, and television personality. He has worked for more than 30 years bringing expert gardening information to home gardeners through radio, television, talks, tours, on-line, and the printed page. Charlie delights in making gardening information simple, easy, fun and accessible to everyone. He's the author of 6 books, has three radio shows in New England and a TV show. He leads Garden Tours around the world and consults with organizations and companies about gardening programs. See more about him at Gardening With Charlie.
Victory Seed Company Logo Victory Seed Company has all the seeds you want for your best garden in 2023.

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