University of Vermont

Indoor Herb Gardening

Rosemary and other herbs in pots by a window

By Carol Holmquist, Extension Master Gardener, University of Vermont

Growing herbs indoors during the fall and winter can be beneficial both for your cooking and for a mood lift, especially during those cold snowy days.

Most herbs need about six hours of direct sunlight either from a south- or west-facing window. Alternatively, you can grow herbs 6 to 12 inches from two 40-watt, cool white fluorescent bulbs for 14 to 16 hours per day.

Keep herbs away from radiators or heat vents, which can overheat and dry them out. The room temperature should be between 65-70 F daytime and 55-60 F nighttime. Grouping plants closely together can increase the humidity, but don't crowd them so much that there is no air circulating around them.

If the indoor air is dry, place the herb pots in a tray of stones. Keep the tray filled with water, but do not allow water to cover the pots' drainage holes.  

You can use single pots or containers large enough for multiple herbs, but whichever you choose make sure that there is adequate drainage at the bottom of the container. If your plants outgrow the container, you may need to repot before winter is over. Combining herbs in a hanging basket may allow for both a humidifying effect and free up counter or windowsill space.

Water regularly and thoroughly with room-temperature water.  Bay, marjoram, oregano, sage and thyme need to dry out between watering. However, never allow rosemary to dry out completely.

Herbs need a well-drained soil that is not too rich. The soil should have a pH of 6-7 and contain a moderate amount of organic matter. If you are using potting soil, check the label to make sure it complies with these properties.

Most herbs will benefit from occasional feeding every few weeks with a liquid fertilizer, such as fish emulsion, seaweed or a general-purpose, water-soluble fertilizer. Don't over fertilize or the plants will produce more foliage but with lower essential oils and, therefore, a bland taste.

Harvest your herbs before they flower. In fact, you should remove any flower heads, and don't allow the plant to go to seed.  For mint-family herbs, make the cut a few inches down the stem and just above a set of leaves. New growth will arise from buds at this point, and a bushier plant will result.

For carrot-family herbs, cut each leaf stalk at the base of the plant rather than just trimming off the tender leaf blades of parsley or cilantro, or the ferny growth of dill. Like other herbs, flowering signals the end of the plant's life, and the flavor may not be as pleasant once the plant flowers.

There are two schools of thought on adding herbs to your cooking. Some people think they should be added at the end of the cooking. However, they can be added at the beginning and at the completion of cooking with additional herbs to taste. When using fresh herbs in a recipe that calls for dried herbs, triple the amount of fresh herbs.

Follow these tips and you can enjoy an indoor garden and fresh herbs all winter long.



Carol Holmquist is a UVM Extension Master Gardener from Montpelier.