Whether you live in an apartment or house, in the long chilly winters of the North or the deep summer heat of the South, you can always grow your own herbs indoors to satisfy your craving for fresh herbs. Tender perennials such as bay and lemon verbena can live on in the controlled environment of your home, and a bush brimming with fresh basil leaves provides year-round culinary excitement. Other favorites such as rosemary, thyme, and oregano can be grown indoors as well. Although indoor herbs will usually be less productive than those grown outdoors, they’ll still give you plenty of fabulous flavor right at your fingertips, and you won’t have to worry about unpredictable spring or autumn frosts, marauding rabbits, or other outdoor hazards.
Some herbs such as caraway and chervil, are difficult to grow inside, but a surprising number of other herbs that will thrive given a little extra attention and the proper conditions, which include the right potting mix, fertilization, water, temperature, and light. To ensure success when you grow your own herbs indoors, it’s usually best to start with plants rather than seeds. Buying plants instead of seeds will put you months ahead (sometimes even a year), and you’ll know what you’re getting. Starting such a project in spring allows you to take advantage of increasing light as well as sales at your local garden center.
Picking the Right Herb Container
Anything from decorative ceramic pots and galvanized metal buckets to common plastic pots can be used as long as they provide adequate drainage. If your favorite decorative pot lacks necessary drainage holes, drill some or transplant your herb to a slightly smaller plastic container with holes that will fit inside it. Choose the largest pot possible to provide more room for growing roots, which will give you a bigger plant to harvest from.
Like any container-grown plant, herbs need a fast-draining potting mix to provide oxygen and prevent root rot. Garden soil just won’t cut it as it is heavy and compacts when used in containers. Look for a premium or professional mix that includes ingredients such as perlite or vermiculite to help loosen and aerate the final mix. I usually start with a high-quality potting mix, then add nutrient-rich compost or earthworm castings along with extra perlite or vermiculite.
Where to Plop Your Plants
Just like outdoors, there are different microclimates within your home. The area next to a window in winter may be too cold for some herbs, while a location near a woodstove or furnace is usually too hot and dry. Likewise, in summer, a large glass window can intensify the heat of the sun, burning some plants in the process.
When you grow your own herbs indoors, the ideal spot is one that receives at least five to six hours of bright light and has good air circulation with temperatures hovering between 45 and 75 degrees, though 55 to 70 degrees is better. Most herbs just won’t thrive in the dry indoor air common to many homes during winter. You can increase the humidity by grouping plants together (don’t crowd them too much) and setting them on water-filled trays with racks or pebbles. Just be sure that the bottom of the pot is not sitting in water.
Choose a sunny location in a sunroom or near a large window with a southern, southwest or southeast exposure. Consider that a roof overhang, patio roof and trees can reduce the intensity of light coming in. Even with our cloudy Pacific Northwest winters, our herbs still receive ample light in our sunroom. If your herbs become "leggy," a simple fluorescent work light with 4-foot tubes will get them the light they need for proper growth. Use grow lights such as Verilux bulbs or economize with one warm and one cool white light. Hang the fixture so that lights are 6 to 8 inches above the plants’ tops. Leave the lights on for 14 to 16 hours a day to keep the herbs actively growing.
Maintaining an Indoor Garden
How often have you heard someone say, “I watered my plant to death”? Overwatering is the single most common cause of indoor plant death. The second most common cause is underwatering. But watering isn’t complicated.
The amount of water each plant will need varies according to its size, the type and size of container it’s in, the time of year, and the type of plant. Plants are dormant, or growing less actively, during the lower light levels of winter, and therefore require less water.
Allow the potting mixture to dry slightly between waterings for rosemary, oregano, sage, thyme, bay and scented geraniums. Keep the mix slightly moist, like a wrung-out sponge, for plants such as basil, chives, lemon verbena and parsley. Let your finger tell you when it’s time to water. Stick your finger two inches into the potting mixture. If it’s dry, it’s time to water.
When herbs are actively growing, you’ll need to fertilize them with a liquid fertilizer every two to four weeks. Organic fertilizer granules that you scratch into the surface every month or two can be used instead of a liquid fertilizer. A healthy, well-tended herb won’t experience many pest attacks, but watch for whiteflies or aphids and use soap sprays to get rid of them.
To keep your indoor herb garden growing strong, repot perennial herbs as needed. Bring in fresh young plants of basil, parsley and sage to replace those that are short-lived or have become woody. And don’t forget the best part—harvesting and using your indoor herbs.