Delicious, fragrant herbs grow all summer long, and many gardeners love growing their own herbs for recipes and herbal teas picked fresh from each plant. While the first frost might feel like it's time to say goodbye to your herbs until the next growing season, it's actually a simple process to keep them alive inside your home throughout the winter.
Wintering herbs indoors only requires a few simple transitioning steps and a sunny window or plant grow light. With the proper care, you'll be able to keep enjoying your herbs during even the coldest months of the year.
Learn how to overwinter garden herbs indoors in this easy guide.
Before bringing your precious plants inside for the winter, determine which herbs can thrive after transplanting. Some herbs acclimate better to indoor environments than others: It's best to learn the temperature range for each species and plan to bring in any perennials that won't survive freezing conditions. Here are the best types of herbs to overwinter inside:
Some common hardy species can survive in the garden over the winter (like rosemary, parsley, thyme, mint, oregano, and sage), but taking cuttings for use in the kitchen may cause damage to the plants that could prevent their growth come spring. To continue harvesting throughout the cold season, it's best to transition them to an indoor environment.
When to Bring Herbs Indoors
Depending on the region you live in, your herbs will need to come inside between fall and early winter. Since different species have various temperature requirements, the best time to transplant herbs comes down to the weather: As a general rule of thumb, move your plants before the first frost of the season to ensure they aren't exposed to freezing conditions.
How to Overwinter Herbs Indoors
If you're planning to uproot your herbs from the garden, consider the root growth of each species. For chives, thyme, rosemary, and oregano, simply shake off most of the garden soil from the roots, repot the plant with a nutrient-rich organic potting soil, and set the pot near a sunny south-facing window.
Growing parsley indoors can be trickier. It has a long taproot that does not react well when disturbed. To overwinter this plant, dig deeply to get as much of the taproot as possible. Repot the plant in potting soil inside a deep container—preferably with 8 to 10 inches of vertical space.
Herbs planted in pots outdoors can be brought inside for the winter with a simple adjustment period. Bring pots inside before the first frost, and keep an eye on the current temperatures in your region. For example, if temperatures are between 40 and 50 degrees Fahrenheit, keep the plants in a room that stays in a similar range and gradually increase warmth over a week or two until you've reached the desired range in your home. This helps prevent shocking your plants as they move from chilly weather outdoors to a warmer environment inside.
You can grow basil fairly easily in a bright window; however, do not dig it up from the garden as you would with other herbs. Instead, either start new plants from seed, buy a small plant to grow indoors, or take cuttings from one of your existing plants. The same can be done with lemon balm, mint, or shiso.
How to Care for Herbs Indoors
Once your herbs are safely inside for the winter, it's time to plan your care routine to ensure they thrive through the cold season before spring weather returns. To keep your plants healthy and continue harvesting from them, here are a few care tips to keep in mind:
Herbs do best with plenty of sunlight—at least six to eight hours per day. If your home has a bright, south-facing window, this may provide a healthy environment, but cold drafts can damage the plants. The best option is a plant grow light: Choose a variety with built-in timers to ensure consistency each day. Since grow lights are ideal for seed starting, this is also a great opportunity to start new herbs that can grow to maturity before transplanting them outdoors in the spring.
One of the trickier things about overwintering your herbs is maintaining the right moisture level. Some herbs like rosemary require more frequent waterings, while others like thyme prefer dry conditions and dislike soggy soil. The most effective way to determine when to water your plants is with a simple touch test: Place your finger into the potting soil and feel the top inch. If the soil is dry, it's time to add water.
Temperature and Humidity
Herbs are known for thriving throughout the summer in hot, sunny weather outdoors, but they will continue to grow in colder temperatures during the off-season. In winter, provide your herbs with temperatures between 65 and 75 degrees Fahrenheit to keep your plants healthy.
Rosemary, in particular, is finicky about temperatures once brought inside. It does best next to a bright window in a cool room. A south-facing window can provide the full sun exposure that it needs, and temperatures between 60 and 65 degrees Fahrenheit are best.
While many herbs don't fare well in soggy soil, they do thrive when exposed to plenty of humidity. Increase the humidity around your plants by misting them daily, placing a humidifier in the room, or creating a humidifying tray. Humidifying trays are an easy option to add moisture to the air naturally: Simply place a tray of pebbles underneath your plant's pot and add water to the top of the pebble line. The water will evaporate on its own around your plant.
Common Pests & Plant Diseases
Spider mites, aphids, and flea beetles are a few common pests that can affect herbs. Before you bring yours indoors, check the foliage and soil thoroughly for pests or diseases. Keep the herbs separate from the rest of your indoor plants for a few weeks to make sure that any problems do not spread. Once this initial period has passed, check your plants regularly for insects, eggs, and webs. Look underneath the foliage as well—this is where many pests tend to congregate.
With herbs or any other plant you're growing for consumption, use integrated pest management strategies that don't involve chemicals as your first line of defense against pests. Give your herbs the best conditions possible to grow: Remove pests by picking or gently shaking them off, and trim off any affected parts of the plant. As a last resort, you can spray them with horticultural oil or insecticidal soap if you see any insect activity.
Your herbs may also be susceptible to fungal diseases like rust. White vinegar is a natural and effective way to remove rust from your plants, which looks similar to its name; rusty-looking orange sections will appear on the bottom of leaves and foliage. Many fungal diseases are common when the plant's roots are too wet. Plant your herbs in pots with plenty of drainage holes, and only water them when the top inch of soil feels dry to the touch.
Indoor Herb Gardening Pests Management Strategies. University of Vermont.