Even in winter we can still grow fresh herbs. In most regions the herb garden is now dormant, but with a little planning you can grow many culinary herbs indoors this winter. An indoor herb garden is not only functional, it can be attractive and provide a remembrance of summer during the dark days of winter.
The first step is to select culinary herbs that will grow well indoors with limited space and light. Chives, parsley, thyme, oregano, basil, and sage are some of the best to try. You can even grow some unusual, small-leaved greens, such as arugula and mache, to complement your winter salads. Most of these herbs grow only 12 inches tall, so they're easy to maintain. For taller herbs, select dwarf varieties, such as 'Spicy Globe' basil, that will fit on a windowsill or under grow lights. You'll get fewer leaves to harvest on dwarf varieties, but the plants are easier to maintain. While some herbs, such as dill and coriander, have edible seeds as well as leaves, don't try to grow them for their seeds indoors. They won't produce enough to make it worthwhile.
Most culinary herbs are Mediterranean in origin. They need sunshine and well-drained soil to grow best. In winter the days are short, and light intensity is diminished. Even if your plants are growing in a south-facing window and receive six or more hours of sun a day, they still may need supplemental light to keep them short and stout in the dead of winter. Place plants under full spectrum fluorescent or halide lights to provide the right amount and quality of light intensity.
Unless you have a greenhouse or large bay window, chances are you'll be growing your herbs under grow lights or on a windowsill. In either case, there will be limited space, so small pots will be a necessity. Sow herb seeds or set transplants in 3- or 4-inch plastic pots filled with moistened soilless potting soil. Group the plants together in a plastic tray to keep the humidity high. However, if you notice mildew on the leaves, space the plants further apart or use a small fan to provide air circulation and keep the leaves dry.
Most herbs need excellent drainage and grow better when kept on the dry side. Water seedlings by pouring water in the tray and letting it soak into the soil, then draining the tray. As the herbs grow larger, you can start watering from above. Add enough water so it pours out through the drainage holes in the pot.
Although many gardeners think herbs taste best when grown in poor soil, plants grown indoors need supplemental fertilizer. Once their true leaves form, feed the herbs with a diluted solution of water-soluble fertilizer.
Harvest herb leaves as needed. The flavor is usually most intense in the morning. For some herbs, such as dill, harvest the whole plant. You can plant dill every few weeks to ensure a continuous supply of fresh leaves.
Any indoor plant will eventually attract some insect pests. Fortunately, most insects are easy to control with water washes or non-toxic sprays. Aphids, whiteflies, and mealybugs are the main culprits you'll find eating your herbs. Wash the leaves periodically with water to remove them. For more severe infestations, spray leaves with insecticidal soap.
With a little care, your herbs will grow strong through the winter, providing fresh seasonings for your meals. Come spring, you can move the plants outdoors into the garden, cut them back, give them a shot of fertilizer, and they will continue to flourish.