Growing food outdoors over winter is easy if you equip yourself with the right gear. Outdoors, we use cloche protection, row cover, and mulches to insulate the soil and keep frost off plants. And we choose the hardiest varieties of plants that can deal with the low light levels, short days, and cold growing conditions.
Growing food indoors can be a challenge, the main challenge in growing food plants (at any time of year) is supplying adequate light. If you can achieve this, the range of plants you can grow is really up to your imagination – and determination. Indoor gardens are in many ways much simpler and easy to control due to lack of uncontrollable factors that may inhibit or contribute to your success.
Light, of course, is central to the process of photosynthesis. Proteins inside the tissues of plants contain chlorophyll, which uses light energy to turn carbon dioxide from the atmosphere into organic compounds, including sugars. Without adequate light, plants will grow spindly and weak, and the textures and flavours we look for in food plants will not develop.
There are some leafy vegetables and herbs that will grow perfectly well on a bright windowsill. But almost all food plants need to be grown in “full sun.” That’s six hours of direct sunlight every day. In the short days of winter, with the sun angled so low in the sky, full sun conditions are difficult to achieve.
Vegetables that produce fruits (tomatoes, peppers, beans…) and roots (carrots, beets, rutabagas…) are highly demanding in terms of light and nutrients. While it’s technically possible to grow any of these indoors with the right equipment, it is simply unpractical. Focus instead on leafy vegetables and herbs, and in particular on ones that can be harvested while immature. These take up less space, and they tend to grow quickly for fast results. The following are all good candidates for indoor growing:
Beets – for baby greens
Lettuce – all types
Spinach – for baby greens
Sprouts & Microgreens
These deserve mention here particularly because they are harvested at such an immature stage that you don’t need to provide supplemental light. Sprouts are seeds that are encouraged to germinate by repeatedly rinsing them in clean water. Sprouting is covered in greater depth here.
Microgreens are produced by densely planting seeds in soil and harvesting them as their first leaf, or leaf pair, opens. With sprouts, you want to choose plants that will germinate fast, so you can complete the whole process within a few days. But microgreens grow in soil, so there is no urgency. Therefore, you can use plants that may take longer to germinate, that would be inappropriate for sprouting for this very reason. The list of possible food plants to grow as microgreens is nearly endless—everything from amaranth to sunflowers, chia to basil, Brussels sprouts to Swiss chard.
Using Indoor Lights
A number of different lighting systems have been designed specifically for growing plants indoors. The secret is to provide as much light as possible in your growing area. Two lights are better than one, and six lights are better than two. So work within the space you have dedicated to the project, and work within your budget.
High output fluorescent tubes are available in various lengths and they can produce a lot of light. We recommend using tubes identified with the code T5. The ‘T’ refers to the shape of the lamp being tubular, and the ‘5’ refers to its diameter: 5/8”. These lamps provide a lot of light for a relatively minimal amount of electricity. They are best used with reflectors in order to maximize the amount of light being projected down onto your plants.
Another ready-to-use kit design is the Growlight Garden, which is ideal for germinating seeds, and growing microgreens or salad greens. Its compact shape means you can install it on a tabletop or kitchen counter for easy access. The curved, reflective dome incorporates two 6400 Kelvin T5 fluorescent tubes to flood the growing area with full spectrum light, while using 20% less electricity. The base tray can be used as a self-watering system, and includes an absorbent sheet that wicks up water from a reservoir and distributes it to the seedling trays by capillary action. The four segmented seedling trays that are included are made from 100% recycled plastic and can be planted in succession for a staggered harvest—so your supply of fresh microgreens never runs out! Enough light is provided that you could easily grow baby salad greens, herbs, or any leafy vegetable. The unit is 2 feet wide, and 16 inches deep.
A lighting kit that provides even greater versatility, but requires more ingenuity, is the SunBlaster system. Tubes are available in 2, 3, and 4-foot sizes with optional reflectors that simply snap into place. The great thing about this system is the end connector cable that allows you to connect one tube to another (to another) so they can be placed side by side with only one power cord. This system can be used in a variety of ways, depending on your imagination. Try building a growing box, with several light tubes on the ceiling, and foil or reflective plastic on the walls.
Innovations are also being made using LED lamp arrays as grow lights. This technology has the potential to use even less electricity, and LED lamps contain components that are less of an environmental concern.
Other Indoor Growing Considerations
Soil: It’s a good idea to use sterilized potting soil for indoor growing. Many people prefer to mix their own soils to meet different custom needs, but bagged potting soil from the garden centre is a safe, general medium to use. Garden soil may contain spores, insects, and microorganisms that are not ideal for indoor growing. Once your soil has been used to grow plants, the root ball and remaining soil in the container can be composted. Potting soil is designed to combine good drainage with some water retention, and it is usually quite rich.
Water: In the most general terms, the roots of plants require oxygen. If containers are kept too wet, or allowed to sit in water, plants will die. Because you need to allow for good drainage, you’ll need to catch excess water and keep any electrical cords perfectly dry. This is a very important factor to consider when planning your indoor garden space.
Containers: Microgreens grow very well in seedling trays or just about any other sort of container. For baby greens, mescluns, and herbs, choose containers that are at least 10cm (4”) deep, and for any larger vegetables, provide even more generous room for roots to grow.
Ventilation: Air circulation will help to speed evaporation of water from the soil and containers, and prevent mould and mildew from becoming a problem. Consider installing a small fan in or near your growing area, just to provide that extra air movement.
With just a few low-tech gadgets, some dedicated space in your home, and a bit of determination, you can produce fresh, organic vegetables for next to no cost. It’s as sensible as it is rewarding, and whether you’re young or old, it’s a great way to learn about gardening.