I’ve been stalling putting together my indoor food production operation because I don’t have a suitable south-facing window with enough light for growing. I have two south-facing windows—one is six inches from the foot of my bed, and the other is in the office, but underneath a giant evergreen. Neither is ideal. So what to do?
R.J. Ruppenthal, author of Fresh Food from Small Spaces: The Square-Inch Gardener’s Guide to Year-Round Growing, Fermenting, and Sprouting, suggests that I use reflected light. By using a strategically-placed light-colored reflecting board, I can amplify the amount of light that my plants receive underneath another window in the apartment.
The following is an excerpt from Fresh Food from Small Spaces. It has been adapted for the web:
Reflected light is a powerful concept that has enabled many urban gardens to succeed. Reflected light is indirect sunlight that is bounced off reflective or light-colored surfaces, and it can still bring a lot of energy to your plants. If you want to grow fruiting vegetables such as peppers or tomatoes, but your garden only gets 3 or 4 good hours of sunlight per day, then reflected light might make up the difference.
Gardening beneath a wall can be a great advantage. Walls that are painted white or a light color, particularly stucco walls, reflect a lot of light and heat. They also can shelter a plant from wind and cool nighttime temperatures, creating a very favorable microclimate for your plants. In the northern hemisphere, south-facing walls are the most effective for reflecting light and warmth. Walls that face either east or west will pick up some additional early or late light and will translate some of this into warmth. Windows also can reflect light and heat, especially if they face south.
You also can increase your available light by adding your own reflector. This could be a piece of sheet metal, a board painted white, or cardboard covered with aluminum foil. Situate it on the darker side of your plants or in a nearby sunny spot where the light can be reflected back onto your growing space. Be careful with mirrors, glass, or any material that intensely focuses light; these could burn your plants or create a fire danger.
Don’t forget artificial light either. Some people grow plants on a balcony or driveway that sits directly under a porch light. If this light source remains on for several hours, perhaps even all night, that extra light energy can generate a lot of additional growth from vegetable plants. Be sure that your light fixture uses compact fluorescent (CFL) lightbulbs. These are much more energy-efficient than regular incandescents, and plants can grow foliage using the type of light they produce.
This raises an additional question: Should you consider using your own artificial lighting? Although hydroponics and indoor greenhouse-style gardening definitely can succeed where the sun does not shine, they are energy-intensive pursuits. Most sustainable gardening advocates would frown on anything more artificial than a lighted grow box for transplants. I would also make an exception for electrical sprouting machines, which use very little energy to produce large amounts of fresh food. But, for all intents and purposes, gardening with artificial light is wasteful unless you have access to renewable energy sources or are using that same light to live by. As the world’s energy supplies grow scarcer and more expensive, hydroponics and artificial growing methods are likely to play less of a role.