Good Life

Over the garden fence: Indoor herb gardens help get you through winter

Herbs such as borage can be grown indoors during the winter to provide flavor in the kitchen.
Herbs such as borage can be grown indoors during the winter to provide flavor in the kitchen. Tribune News Service, file

Now that colder weather has finally arrived, you might want to consider an indoor gardening project. Growing herbs in pots will add interest to your meals and color to your windowsills.

Some annual herbs can be started from seeds in containers right now to provide fresh seasonings for cooking this winter. And once the weather warms in the spring, plants can be set in your garden to continue their life cycle.

Several herbs you might like to grow are anise, basil, borage, chive, coriander, dill and oregano. If your local seed source doesn’t stock herb seeds at this time of year, you may have to order by mail through a myriad of gardening catalogs.

Before you begin, let’s look first at what you will need for adequate growing conditions. Most culinary or kitchen herbs should get at least 5 hours of sun prt day. A sunny window is a good location, as long as the reflected heat isn’t too intense. If you don’t have a window with direct sunlight, find a spot that will give your herbs plenty of light and plan to move them into the sun for a few hours whenever possible.

If you don’t have direct sun, consider using fluorescent lights. Lighting suppliers often carry special grow lamps you can use with plants. A combination of fluorescent lights and several incandescent lights will work well also.

If you are going to use artificial light to grow herbs, the lights need to be on for 14 to 16 hours a day to give plants enough light energy. Place lights about 12 to 18 inches above the top of the plant. If the light source is too far away, not enough light will reach the leaves to maintain growth. I have seen some attractive lighting planter designs that complement the interior designs well.

Most herbs will be happy under the same temperature and humidity you find comfortable. Hot and dry air is the greatest indoor danger for plants. Remember this if you have a woodstove. Most herbs will grow in normal room temperatures at 68 to 70 degrees. Air humidity should be about 30 to 50 percent. If humidity levels are lower, place a dish of water near the herb plants.

Once indoor conditions are right, you can go ahead and sow your seeds. You can start seeds in just about any container as long as it has a drainage hole in the bottom.

Select a germinating medium that is loose, drains well yet holds moisture. You can use a medium that you would use to start your seeds for the garden. When sowing the seeds, mark off rows on the smooth surface about 2 inches apart and  1/8 to 1/4 inch deep. Place seeds in these shallow furrows and cover to the depth listed on the package. In general, they will be covered to about twice their diameter. Very fine seeds may even do well if only pressed into the surface of the material. Seeds set too deep may not germinate or may not have enough energy to come through the surface.

Water the sown seeds with a fine spray to avoid washing seeds around in the medium. If you have used small containers, you can also soak the bottom of the container in a pan of water until the surface is wet. In either case, drain off all the excess water after the initial soaking and label what you have sown and the date. Place the container in a plastic bag to form a small greenhouse to keep the surface of the medium wet, and then set it in a fairly warm spot — 65 to 75 degrees — but not in direct sunlight until germination begins. Keep the top of the bag open slightly to allow some air and moisture to escape.

When germination begins (generally in two to three weeks) remove the covering and move the container to a cooler area (60 to 70 degrees), where it will receive good light but not direct sunlight.

Gradually give the seedlings more sunlight over the next week or so. Turn the container every day to expose all sides of the seedlings to equal light. Water management is critical during this stage. Excess water may cause stems to rot at the soil line. To eliminate this problem, don’t water too frequently; keep fresh air around the seedlings and the temperature in 60s.

When the seedlings have two sets of true leaves, they are ready to be thinned. If you have used a temporary container this is also the time to transplant into a larger or more permanent pots, which will give your herbs space to develop. If this will be a permanent indoor pot you may want several plants per pot.

As your herbs grow, be sure they get 5 hours or more of light per day. Low light levels will produce weak, spindly plants. Too much water will have the same effect. Herbs generally do not need much fertilizer but they do respond to some. Select a soluble fertilizer and apply it at half the strength on the label directions. Over-fertilized plants often will have a poorer flavor than those that grow at a moderate rate. Remember that you can always add more fertilizer but you can’t take it back.

Don’t be afraid to clip off the top of the main stem to encourage branching and to develop a fuller plant. As you harvest leaves and stems later, new side growth will develop and fill in the plants. Happy growing.

Bill Lamont is a professor and extension vegetable specialist in the Department of Plant Science at Penn State and can be reached by email: