Herbs

Basil Needs Special Care in the Winter—What You Should Do Now For a Better Harvest

Fresh basil is a flavorful, versatile ingredient in cooking, and one of the best ways to ensure an abundant supply is to grow your own.

But what about after the growing season ends? Temperatures below 50°F can damage basil leaves, and....

exposure to 45°F or lower can kill the plant. This is true for different types of basil, including Italian, Thai, and purple varieties.1

Because basil is perennial only in USDA hardiness zones 10 through 12, gardeners in cooler climates must take special care at the end of the growing season to extend the harvest. Here's how to overwinter basil after the growing season ends.

How to Care for Basil in the Winter
Bringing Indoors
It's possible to dig up in-ground basil plants, pot them up in containers, and keep them indoors to extend their life for a few months into winter.

Basil plants grown outdoors in containers can be brought inside for the season—just be sure to follow the same steps for bringing houseplants indoors for winter.

Bring basil plants inside before night temperatures consistently dip into the 50°F range to avoid damaging the plants' delicate foliage.



Light
Basil requires full sun, so plants brought indoors for the winter will need to get at least 6 to 8 hours of bright, direct sunlight per day, such as from a south-facing window.

If your space can't provide this much light, you'll need to use a grow light instead. Program the light to run for 12 to 14 hours each day and position it about 12 inches from the plant.

Watering
Keep up with regular watering through late summer and early fall. Basil plants that are stressed by drought conditions will be less likely to weather colder temperatures or survive the transition from outdoors to indoors.2

Once it's inside, water your basil plant enough to keep the soil evenly moist but not soggy. Note that the plant will require less water than it does in the summer months.

Fertilizing
Avoid fertilizing any basil plants that you'd like to overwinter after August. This way, your basil can acclimate itself to colder temperatures during September and October rather than expending energy on putting out new growth.2

After you bring plants in for the winter, it's not necessary to fertilize if you're using fresh, compost-based potting mix in the container.

Pruning
Continue harvesting basil until before your region's first frost date. Avoid pruning plants that you'd like to overwinter indoors after this date.

Take cuttings to propagate indoors before your region's anticipated first frost as well.

Pests
Examine outdoor basil plants thoroughly before bringing them indoors for the winter. Look for signs of common pests like whiteflies and aphids.

Check the undersides of leaves for the eggs of insect pests. Spray away pests with a strong jet of water or use an organic insecticidal soap to remove them, making sure to follow product directions carefully.

Drying Basil in the Winter
Overwintering basil plants indoors can be difficult due to this herb's significant light needs. An alternative is to harvest and preserve basil at the end of the growing season to use throughout the winter.

You can make your own dried basil by cutting stem tips throughout the growing season, tying them together with string, and hanging them upside down in a dry, well-ventilated place.

At the end of the growing season, you can cut entire plants down at the base of the stem and hang them to dry. Wait until the leaves are completely dry and crispy before stripping them from the stem and storing them in an airtight glass jar or plastic container.

You can also preserve basil by blanching, chopping, and freezing the herb in oil or making it into pesto that can be frozen for later use.

Basil Winter Care Tips
You can root basil cuttings in water at the end of the growing season rather than digging up plants to bring indoors. When roots are one inch long, pot up the cuttings and care for them as usual.
Another option to enjoy fresh basil in your kitchen all winter long is to grow it hydroponically with a kit or indoor garden system.
In zones 8 and 9, you may be able to use season-extension tools like cold frames or cloches to help outdoor basil plants survive longer in the fall.3
While it's possible to extend the life of your basil plants by bringing them indoors for the winter, they will eventually flower, set seed, and die back. Plan to seed new plants or purchase basil starts the following spring.