Pot up herbs for fragrant, fresh green leaves indoors in winter.
Herbs set on a sunny window sill through the winter can be used at any time.
Herbs easy to grow in pots indoors include anise, basil, bergamot, borage, calendula, caraway, chamomile, chervil, chives, coriander, dill, lemon balm, lemongrass, pot marigold, marjoram, nasturtium, parsley, peppermint, rosemary, sage, summer savory, and thyme.
Ways to Grow Herbs Indoors
• Annual herbs can be started fresh from seed in fall. Sow seed in 3- to 4-inch (7.6-10cm) pots so they will have room to grow through the winter. Annual herbs include anise, basil, borage, chamomile, chervil, coriander, dill, fennel, pot marigold, sweet marjoram, and summer savory.
• Perennial herbs like sage, chives, and rosemary can be started from cuttings or division. Take 4-inch (10cm) cuttings and root them singly in pots. Cuttings should be taken from new growth. Keep cuttings moist to encourage roots to grow.
• Perennial or annual herbs growing in garden soil in the summer can be potted up for winter indoors. Leave the plants in their new pots outdoors in a shady spot for 1 week before bringing them indoors; this will allow them to adjust to the change in light. Be sure to pot up herbs into containers large enough to accommodate their root system.
• Herbs growing in containers year-round can simply be moved indoors when winter comes. Again be sure to help them adjust to the change in light by setting them in the shade for a week before bringing them indoors.
What Herbs Need Indoors
• Light: Herbs need plenty of light each day. A sunny window is best. Herbs also can be set under fluorescent lights; set the plants 6 to 8 inches (15-20cm) away from the lights.
• Temperature: Most herbs want daytime temperatures between 60 and 70°F (15.6-21°C) with cooler temperatures of 50 to 65°F (10-18°C) at night. However, most herbs will survive at a constant temperature.
• Water: Water herbs thoroughly then allow the soil to nearly completely dry before watering again. Don’t overwater. If humidity is low, spray plants with a light mist a couple of times a day.
Overwintering Herbs Outdoors
Mints, oregano, and tarragon are hardy perennial herbs that can survive outdoors in winter—even under snow. (But if you want to use them fresh through the winter, divide and pot them up to bring inside.) Bay, rosemary, lavender, pineapple sage, and lemon verbena are tender perennials that will take some frost but their roots will be killed off outdoors if the temperature dips below 15°F (-9.4°C).
The best protection or herbs outdoors in winter is a plant blanket or a blanket of snow. Plant blankets are made from spun poly material and can be purchased at most garden shops.
Perennial herbs outdoors in winter need protection from the drying effects of winter wind most. Besides plant blankets, you can cover herbs with evergreen boughs or surround them with burlap-covered frames. Small herbs can be covered with straw or leaves when the soil freezes. Remove the mulch gradually in spring.
More tips at How to Start an Herb Garden.