For anyone addicted to the fresh food of harvest time, indoor gardening must surely be the holy grail. Think about it: fresh fruits and vegetables all year long; tremendous money savings; being able to continue a favourite hobby regardless of the weather; endless rewards and learning experiences; and the possibility of transplanting outdoors in your garden or moving containers onto patios and decks when the warmer weather arrives.
What’s not to like?
Fruits, vegetables and flowers can all be grown indoors, as long as the right conditions are present. Vegetables like carrots, radishes, lettuce, peppers and tomatoes take little space and do well indoors. As long as you’re growing vegetables, why not add a selection of herbs to spice up your cooking? Many can be grown indoors on a bright windowsill throughout the year. Regardless of what you plant, choose seeds that are specifically suited to growing indoors in containers
Of course, to obtain a good yield, there are some important elements to consider:
Before you begin, identify a location that will provide enough light – typically plants need about 6-8 hours each day to grow and reach maturity. This amount is suitable for vegetables that can take partial shade, such as some root crops, leafy vegetables and legumes. All other vegetables would benefit from at least 8 hours of light. If you are concerned that your plants are not getting enough light or are taking on a ‘stretched’ appearance, you may want to consider a supplemental light source such as a plant lamp. (There are many different types of lights and spectrum intensities available. A visit to a reputable nursery will help you understand the options and get the guidance you need to get through the darker days of the year.)
When it comes to containers, there is room for flexibility and creativity. Chief considerations are proper drainage holes and enough depth for roots to develop properly. Since all plants grow differently, you might consider varying the size and depth of the container depending on each variety you grow.
Contrary to popular belief, square containers are actually the most suitable as they encourage roots to spread out more evenly. Round pots can cause roots to grow in a circular pattern and eventually begin to restrict themselves. Make sure to provide good drainage and avoid the temptation to overwater (more on that later) – this will also help avoid root issues, such as root rot.
Larger vegetables such as tomatoes or peppers should be potted in containers at least 30-45cm (12-18in) deep, with support for when the plant gets taller. Rooted vegetables such as carrots should be in deeper pots to encourage successful root formation. Salad greens and radishes can be planted in flats that are 2-3 inches deep, as their roots are more shallow. If you’re new to sprouts, there are specific containers available that make sprouting super easy and safe to consume – you’ll have fresh sprouts within a week!
Provide the right amount of air circulation and ventilation for your plants. Keeping plants in a closed room may cause excess carbon dioxide to build up, so open the door to your growing room whenever possible. Good air circulation will help prevent plants from developing root diseases, which can become an issue when growing indoors. As the plants mature, a fan can also help move air and contribute to a healthier growing environment.
Constant temperatures best suited to your each of your plantings will help them mature properly and successfully set fruit. Leafy greens, such as lettuce, spinach or chard, do not require the same temperatures as heat-loving plants like tomatoes and peppers. Salad greens can withstand temperatures of 15˚C while tomatoes love temperatures at or above 20˚C.
Water is the giver of life. But too much water can do the opposite. When plants are growing indoors, they don’t receive natural watering from rainfall, so getting the right amount of water is an important challenge. As a rule of thumb, if pots are small, they may need to be watered more frequently than larger pots. But only add water if the soil feels dry below the surface. If soil appears to look wet on the surface, this may not necessarily mean that it has sufficient moisture. Stick your finger in the container. If it feels damp, it may not need watering on that day. It may seem obvious, but remember to only water when the plant needs it. Signs of over watering can include mold on the soil surface, root rot (which leads to stunted growth), yellowing or browning of leaves, and dropping of both new and older leaves. Ignore these signs for too long and you can expect the plant will die.
Feeding your little seedlings goes hand in hand with watering, especially if you are planting in a soilless mix. When you water, essential nutrients are flushed away, nutrients that are critical for the plant to bear fruit. Use a water soluble fertilizer or, as an alternative, organic fertilizers such as fish emulsion, seaweed product, or worm castings. Read package labels to determine the proper amount of fertilizer for each type of plant. And be careful not to over fertilize – sometimes less is more. Over-fertilizing can cause salt build-up, which can burn delicate roots, often manifesting itself as burn on leaves.
One advantage to growing both vegetables and flowers indoors is that there are fewer pests to be concerned about, such as white fly, aphis, mealy bugs or spider mites. Using a good sterile soil mix as well as sanitary containers will create an even better start for your plants.
Some of my personal indoor favourites include sprouts and microgreens. They are so easy, inexpensive to keep and nutritious. Many types of plants in containers will work in your environment – just follow the simple steps above to ensure a successful start and you will be harvesting in no time.
Heidi Carmichael is a horticulturist who coordinates the trial gardens at Veseys Seeds in York, PEI.