Herbs have properties beyond flavoring foods | Features

Many herbs are hardy and can take the chilliest of winter temps outdoors. Rosemary and thyme, for instance, are staples in my winter kitchen garden. Less hardy herbs like basil and parsley are not as tolerant of winter’s cold. Parsley is somewhat cold tolerant but will need to be brought inside during periods of extreme cold. Basil is a summer annual that grows best outdoors in the heat of summer near tomatoes. However, basil can be started indoors several weeks before the summer season begins. If you have a sunny south-facing window, or a lightbox system for starting seedlings, you can grow fragrant and tasty herbs like basil and parley indoors in winter.

The primary limiting factor for a winter herb garden is light. Herbs grown inside will need plenty of sunlight from a south- or west-facing window and may need to be supplemented with artificial light. Clemson’s Home and Garden Information Center provides factsheets that can be used by the “DIY” gardener who would like to construct a lightbox system for growing indoor herbs like basil or for starting early spring vegetables like parsley and microgreens.

It is possible to grow seedlings at home under fluorescent lights alone. Forty-eight-inch, 40-watt fluorescent tubes, placed 2 to 4 inches above the seedlings, on a timer, is an adequate set-up. The light should be just above the soil line in the beginning and raised to maintain a 2- to 4-inch gap between the light and plants as the transplants grow. Maintaining a small gap between the light and plant will create a stocky plant. LED lights also work well and don’t use as much power. Hang them 6-12 inches above the plants. Set the lights to turn on and off automatically to make sure the herbs get consistent light each day.

Basil (Ocimum basilicum) has so many cultivars that one could focus an indoor garden entirely on basil. Italian types such as Genovese and Lettuce Leaf have large, sweet, green leaves that are great for making pesto. Purple basils are mainly used for decorative value but also make beautiful rose-colored vinegars. Lemon-scented cultivars are wonderful with fish.

If a gardener plans to transplant basil outdoors, one can start seeds indoors, allowing four to six weeks for germination ahead of outdoor planting time. Plant basil seeds ¼-inch deep. Germination takes 5 to 10 days at 70 F. Once seedlings have two sets of true leaves, individual plants should be potted into small containers for faster growth. Harvest a few leaves if desired. Put these plants in a sunny window or — if you have them — under specialized grow lights. Do not over-water, and do not let the plants stand with water in their saucers. Basil should not be transplanted into the garden until the daytime temperature is consistent in the 70s, and the nighttime temperatures are above 50 ºF.

Fresh parsley (Petroselinum crispum) is a versatile herb for cooking and for garnishes. It’s also an adaptable plant to grow indoors which adds color to a bright windowsill. Curly parsley is best for garnishes, while Italian parsley has a sweet peppery flavor when added to salads, or used for seasoning soups, stews, or pasta. When growing parsley in pots, it is important to choose the right container. You will need a pot with drainage holes in the bottom, and a saucer or outer pot to catch any drainage water. Successfully growing parsley indoors is often a matter of finding the right balance of watering not too little, and not too much. To find the right balance, water your indoor parsley plant frequently enough to ensure soil does not dry out completely between waterings. Check that the soil has not become waterlogged following watering.

Plant parsley seed indoors in early spring. Place seeds around ¼ inch deep into fresh potting mix. Parsley seeds will take about four weeks to germinate, though to speed up the germination rate, try soaking the seeds for a few hours before planting. Parsley needs a lot of light, so the best place to grow it indoors in a sunny windowsill. It needs around six hours of direct sunlight per day to thrive. Consider supplementing with a grow light if you don’t have a bright spot where it will get this much light naturally. Parsley plants also prefer a humid environment. If you are growing your parsley plant in a kitchen, then the humidity may be sufficient. However, it may need to be misted regularly. Use a good quality water-soluble fertilizer during watering every two weeks.

A note of caution. Don’t use garden soil for starting indoor plants. Garden soil may contain weed seeds or fungal diseases. To find additional information about making soilless mixtures to start seeds indoors, go to Clemson’s Home and Garden Information Center. Starting Seeds Indoors and Indoor Plants — Soil Mixes are available online at hgic.clemson.edu.

Even in the deep midwinter of January, one can do some winter gardening by growing herbs and by starting early spring vegetables ready to transplant when warmer weather arrives. The seed catalogs are on their way.

Happy New Year from Aiken’s Master Gardeners.