If you were a proud grower of basil, parsley, and oregano all summer long, you might be wondering if you can transport your thriving garden indoors to enjoy those home-grown herbs through the winter. Thankfully, there's no need to let your established summer herbs die off with the cool weather. Even plants that are accustomed to outdoor conditions and lots of sunlight can grow healthily inside—all it takes is a few simple steps to transition them gently.
To get started, we asked experts Venelin Dimitrov and Gladys Mbofung-Curtis about the best ways to move herbs indoors and continue to enjoy them all winter long. Here's what you need to know to keep your herb garden growing year-round.
Meet the Expert
- Working time: A few hours
- Total time: One week
- Skill level: Beginner
When to Bring Herbs Indoors
Herbs such as lemon verbena, basil, dill, and cilantro should be brought indoors before the first frost. Once inside, these plants do best with indoor temperatures ranging between 65 to 75 degrees Fahrenheit. Several hardy herbs can actually overwinter outdoors, including mint, oregano, parsley, sage, and thyme.
“[These species] go dormant before rallying again in the spring, but you’ll need to take precautions so they don’t succumb to frost,” says expert Venelin Dimitrov, horticulturist at Burpee in Warminster, PA. “Herbs in the ground should be placed in a well-drained area and covered with a few inches of mulch. If your herbs are in containers, make sure the pots are made of glazed clay so they don’t crack with freezing temperatures.”
Some herbs, such as tarragon, chives, and mint benefit from time in cold weather as it brings on a rest period, followed by fresh growth.
“It’s best to leave [these] outdoors during the rest period, then move them indoors three weeks post the first frost,” adds Dimitrov. You’ll want to bring rosemary and parsley inside once overnight temperatures settle into the mid-to-low 30s range, and lemongrass and other herb grasses as soon as their top growth starts to turn brown.
Tools and Supplies You Will Need
- Gardening gloves
- New pots (for in-ground herbs)
- Pruning shears
- Fresh potting soil
- Clean washcloth
- Magnifying glass
- Insecticidal soap, Neem oil, or horticultural oil
- Garden fungicide
Step 1: Check for Pests on Outdoor Herbs
Inspect the tops and undersides of the leaves, joints, stems, pots, and saucers of your plants with a magnifying glass for any indication of pests (such as webbing, small bumps, or unusual discoloration) before moving herbs indoors. “While herbs are still in the ground or in containers, rinse them well with a garden hose,” says Mbofung-Curtis.
If necessary, treat pests such as aphids, mealybugs, mites, or leafhoppers with insecticidal soap (like Garden Safe Insecticidal Soap Insect Killer), and any fungal issues such as black spot, rust, or powdery mildew with fungicide (like Garden Safe Fungicide3). Neem oil and horticultural oil are also effective at treating pest infestations. While indoors, herbs can still fall victim to fungi or insects, so continue to inspect your plants throughout the winter.
Step 2: Prune the Herbs to Encourage Healthy Growth
While still outdoors, remove dead or broken branches and diseased leaves. Next, lightly trim away three to four leaves per branch, along with three to four buds to help activate new growth.
“Don’t remove more than 1/3 of the top growth, or you’ll run the risk of reducing the herb’s ability to photosynthesize, stunting its growth,” says Gladys Mbofung-Curtis, a plant scientist at Spectrum Brands in Madison, WI. “At the same time, if you’re re-potting, be sure to prune 1/3 of the lateral roots to stimulate root growth in the new container.” Over the winter, continue pruning the leaves and buds of your herbs to encourage airflow and growth.
To prune the roots, start by gently squeezing off excess dirt around them. Then trim the roots symmetrically with a pair of pruning shears before re-potting your herbs in fresh soil.
Step 3: Choose New Indoor Pots
When it comes to choosing pots for your herbs, the size of the pot depends on how large your plant is. “Herbs don’t require a lot of soil, and will survive in relatively small containers," says Dimitrov. "In fact, thyme, lavender, oregano, rosemary, and chamomile thrive in the cracks and rocks on the Mediterranean coast."
Containers should be large enough to comfortably hold the roots and keep plants upright when they reach maturity. “Re-potting should be done in a container that is at least two inches larger than the one containing the plant. A good rule of thumb is to choose a pot that’s at least 1/3 as tall as the mature plant, and 1/2 to 3/4 of its mature width,” adds Mbofung-Curtis.
Step 4: Add Fresh Soil
Prepare fresh soil to give your herbs the nutrients they need to thrive during a transition indoors. “A good mix includes two parts potting soil and one part perlite or sharp sand,” says Dimitrov. “Many herbs like basil, rosemary, and thyme prefer a nonacid soil, so it’s best to add a teaspoon of ground limestone per six-inch pot.”
When transferring your plants, begin by placing a layer of soil on the bottom of the container, then set the herb on top. “Fill in the spaces around the roots with more potting mix, then press the soil firmly down around the plant's roots, leaving about an inch between the soil and the rim of the pot. Water until it drains out onto the saucer,” notes Mbofung-Curtis.
Step 5: Ease Your Herbs Indoors
An abrupt change in environment can be stressful to herbs, resulting in yellowed leaves, wilting, and even death. Place potted herbs in a partly shady area outdoors for a few weeks before moving them inside.
“Bring them indoors at night for the first few days, then take them back outdoors during the day when temperatures are not yet at a freezing point. Gradually increase the number of days the plants spend indoors, setting them up indoors in an area with indirect light,” says Mbofung-Curtis. “After a couple of weeks, you can move the pots to a spot with more direct sunlight.”
Like many other outdoor plants, herbs can have an adjustment period when moving inside. Don't be alarmed if you notice your plants dropping a few leaves: It's perfectly normal as long as the stems and roots stay healthy.
Step 6: Ensure Proper Sunlight Exposure
Place potted herbs in a southern-facing window where they’ll receive six to eight hours of light per day. If you don’t have plenty of sunlight indoors, supplement with grow lights. “You can use regular fluorescent tubing, hung twelve inches above the plants, or more energy-efficient LED lights placed six inches over your herbs,” says Mbofung-Curtis.
Rotate the pots regularly to expose all sides of the plant to the light. “Adjust the placement and height of the lights as your herbs develop and mature,” adds Mbofung-Curtis. “A sign an herb is not receiving enough light is the presence of ‘leggy’ stems that are white or yellow in color.”
Step 7: Create a Watering Schedule
While herbs are famous for being drought tolerant, they still need regular watering to thrive. “There’s no easier way to find out if they’re thirsty than by sticking your finger in the soil,” says Dimitrov. “The top few inches should be dry, but then you should hit moisture.”
Many herbs, including marjoram, oregano, sage, bay, and thyme, will benefit from letting the soil surface dry between watering (though not to the point that the leaves wilt). Basil, dill, and rosemary can't dry out completely—or you’ll have trouble reviving them—while mint and lemon balm like more consistent moisture. Misting the leaves daily with water will increase moisture levels and slow leaf droppings.
Step 8: Propagate New Plants (Optional)
Snipping sprigs will encourage your healthy herbs to produce new growth and stay compact until you can move them outdoors come spring. Even better, you can use these cuttings to expand your supply of fresh herbs.
“Take cuttings of soft-stem herbs like basil, lemon balm, and mint, then place them in a small vase of water while they develop roots,” says Mbofung-Curtis. “For herbs with woody stems such as rosemary, sage, oregano, and thyme, make sure the cuttings are green (as brown stems will not sprout root as easily). When the roots are a few inches long, pot the cuttings.” Stems from herbs like parsley, dill, and cilantro will not root with this method, as they’re propagated by seed.