Copyright 2010 Jim Long
Bringing Herbs Indoors for Winter
Every fall I receive questions from gardeners about bringing their herbs indoors for the winter. I’ve found that most people (myself included) aren’t willing to do all of the things necessary to get their herbs to thrive indoors, and ultimately before spring, will be disappointed. Here are the basics for growing herbs indoors in winter.
1-Start with smaller plants, which transplant easier than larger ones, and give the plant a slightly larger pot than you think it needs. For example, a well-established basil plant, 24 inches tall in the garden, will be fairly difficult to dig and transplant. But if it’s already growing in a pot, you can shear it back by about a third of the size before bringing it indoors. Also, be sure to spray it well, under the leaves, on the stems and around the rim of the pot with one of the food-safe insecticides listed below before bringing the plant indoors to avoid transporting insect pests with the plant.
2-Most culinary herbs require full sun to survive. "Full sun" means at least 8 hours of sunlight per day. Less light and the plants will be spindly and weak and not grow. A sunny window facing south, can help but the danger there is the window glass may act like a magnifying glass if the plant is too close and actually scorch the leaves. And most windows in winter only provide about 3-5 hours of actual sunlight each day, less than is necessary for an herb like basil to grow well. The most successful way to grow herbs indoors is to use either a greenhouse room that gives all day sunlight, or a grow-light with a timer set to be on 8 hours each day.
3-Once the plants are moved indoors, plan to spray the plants every two weeks with a safe insecticide, such as Safer's Soap solution, or ultra-fine oil spray to prevent mealy bugs, red spider, scale insects and aphids. Keeping current with the spraying will help avoid insect problems that once started are difficult to control and can destroy the plants. (To make your own oil spray: 1 cup vegetable oil mixed with 1 tablespoon dishwashing liquid. To use:
mix 1 tablespoon of mixture with 2 cups of water. Fill a spray bottle and shake wel, then spray).
Plants that work well indoors under a grow light or in a greenhouse room include chives, garlic chives, parsley, marjoram and oregano. Basil is more difficult indoors but can survive if provided with enough light.
Rosemary, on the other hand, should be kept in an unheated, well lighted room, such as a garage or enclosed back porch. Water it sparingly (about every two weeks) Too much water, or too warm a room, will kill rosemary. Sage, thyme, oregano, chives (and usually rosemary) are all hardy outdoors and can usually be harvested for much of the winter from the garden.
Once you have your herb plants indoors, don’t fertilize them. Plants go into a period of semi-dormancy, meaning they do little growing indoors in winter. Fertilizing them can actually cause them to die. Wait until March, when the days are beginning to get longer, then begin lightly fertilizing.
My book, Growing & Using the Ten Most Popular Herbs, is an excellent resource for this very thing. It's available from my website: www.LongCreekHerbs.com and lists the requirements for growing all of the top 10 most useful culinary herbs. Happy gardening!