Grow Basil Indoors: A Winter Guide for Fresh Flavor

After enjoying a summer of fresh basil and mozzarella sandwiches, caprese salads, and just-picked basil leaves on homemade pizza, the end of garden season is sometimes a bit of a downer. While a collection of dried basil is lovely, it just doesn’t replace the burst of flavor that you get from garden-fresh, homegrown basil.

The good news is that you don’t have to wait until next summer to enjoy fresh basil! Basil plants are quite easy to grow indoors throughout the winter months, provided they have water, plenty of light, and regular pruning. You can start new basil plants from seed, but you can also transplant an existing plant from your garden or take a cutting (if your garden basil plants are quite large). The key is doing it at the right time so that you can preserve the health of your plant and continue harvesting leaves all throughout the cold months. 

Whether you want to save seeds to plant indoors (or outdoors in the spring) or bring your basil plant indoors to continue growing, you’ll want to take action before 45°F – 50°F weather hits. While one 50°F day likely won’t kill your plant, multiple 40°F – 50°F days will cause the leaves to begin to blacken or possibly cause the entire plant to die. Basil plants love warm, sunny weather! 

How to Save Basil Seeds

When the flowers start to turn brown, but before they blacken, it’s time to save seeds. This is generally in the fall months, depending on your grow zone. 

Grabbing the seeds from your basil plants is easy! Just run your hand down the basil stems to collect the seed heads. Then, break them open and you’ll find tiny black seeds. If they’re completely dry, go ahead and store them in a paper envelope or an airtight container in a cool, dry place. (If they’re not dry yet, set them on a paper plate or paper towel for a few days to a week, then store.) 

For further instructions, see my full tutorial on how to save basil seed.

Once you have your seeds collected, you can either save them until spring or replant them inside to grow during the winter months. If you grow your basil plants from seed, they should reach maturity in about 4-6 weeks. 

When Should You Bring Basil Plants Indoors for the Winter?

Transplanting your basil plant into a container to bring indoors is an easy way to preserve it without having to start all over with new seeds. With proper timing and care, you can have a continual basil harvest from summer to fall to winter.

The best time to bring your basil plants inside is before temperatures start hitting 50°F and the leaves begin to turn brown. Starting with a healthy, green plant will make it easier for your basil to make the transition to indoors. 

If you have large, older plants in your garden, it can be a bit more difficult to transplant the entire plant, as the plant’s roots can plummet down to 12 or more inches deep. Transplanting the entire plant works well for smaller plants, but if you have larger plants, you’ll likely have better success taking a cutting. 

Method 1: How to Take Basil Cuttings to Grow Indoors

Rooting basil from a cutting is simple as long as you have a healthy mother plant. It takes about a week to propagate a new plant from a cutting. Follow the instructions below, or check out my full tutorial for more tips and pictures: How to Root Basil from Cuttings

1. Use a sharp knife or pruners to cut a long basil stem near a leaf node. Remove any lower leaves so they don’t get wet while propagating.  
2. Place the cut end in a jar of water, making sure at least 1/2″ of the bottom of the stem is covered by water.
3. Keep the water fresh by replacing it every 2 days. Within a couple of days, you’ll start to see small roots beginning to form. 
4. When the roots are 2″ long, remove the plant from the water and pot it up with potting soil in a medium-size pot. 
5. Keep your basil plant in a sunny spot. Basil needs lots of heat and light in order to thrive! A grow light can help in areas that don’t get enough natural light or heat. 6-8 hours of sunlight per day is best.

Basil is one of the easiest herbs to propagate from cuttings, so do a few of them to pass around to friends or neighbors! It’s a simple, thoughtful way to share this delicious herb and spread some greenery during the darker months.

Method 2: How to Transplant a Basil Plant Indoors

If you have a smaller basil plant in your garden, you can simply dig it up and pot it to continue growing indoors! 

What You’ll Need:

• 15″ deep pot
• Trowel
• Potting soil (I like this Espoma potting soil.)

How to Transplant Your Basil

1. Start by adding some potting soil to the bottom of your pot.
2. Next, head out to your garden and begin gently digging around your basil plant. Aim for about 6″ around the plant and 6″ down, carefully loosening the plant as you work and making sure the root ball stays intact.
3. Once it’s free, gently lift your plant into your pot. Grab a couple of handfuls of garden soil to add to the pot in order to aid in a gentler transition. Then, fill the rest with potting soil. 
4. Water your basil plant just until you notice a drop or two leaking out from the drainage holes. It’s important to keep your soil consistently moist for the first couple of weeks or so as the plant’s getting re-established. Feel the top layer of soil every couple of days, and water whenever it feels dry. Again, add just enough water to where a couple of drops drip out from the bottom—then stop. 
5. Place your basil on a sunny windowsill or another spot that gets lots of natural light. Basil needs plenty of warmth and light to grow. 6-8 hours per day is best, which can be difficult during the darker winter months. If you notice your basil plants start to become tall and leggy, turn yellow, or droop, they’re probably not getting enough light. Adding supplemental lights (like a grow lamp) can help your plant make it through the winter.

How to Prune Your Basil

Remember, basil needs three things to do well indoors in the winter: water, plenty of light, and regular pruning. It’s important to trim your basil plant regularly. And hey, you get delicious fresh herbs out of the deal! Basil that’s not pruned often enough will become tall, leggy, and unhealthy. And basil that is pruned regularly will produce large, healthy yields. 

You can start pruning your basil plant when it’s still young. As soon as you see one or two stems coming off the main stem, grab your pruning shears. 

To cut your basil, find a stem that has a set of leaves growing on each side of it. Then, take your shears and cut the middle stem to the base, right above the set of leaves. Cutting off the top of this main middle stem will encourage outward growth and new shoots from the leaf sets. 

Then, go throw your freshly harvested basil in a caprese salad or a batch of pesto! 

Continue pruning your basil about every 2-4 weeks to encourage hearty growth. You can prune several stems at a time, but don’t remove more than a third of the plant at once, or you may shock the plant. 

Can All Basil Plants Be Grown Indoors?

Most varieties of basil make good container plants for growing indoors in the winter. Compact plants and slow-bolting varieties work best. These include:

• Genovese basil (sweet basil). This popular variety produces large, sweet leaves that are wonderful for cooking.
• Thai basil. Thai basil has an anise/licorice flavor and is commonly used in Asian dishes. 
• Greek basil. Greek basil is a dense, small plant that’s perfect for container gardening. It’s highly aromatic with a slightly spicy flavor. 
• Purple basil. Purple basil often tastes reminiscent of cloves or pepper. Its dark purple color is lovely in salads and as a garnish.

Keep in mind that basil plants need plenty of sunlight, regular watering, and regular pruning in order to thrive.

Large, fast-growing varieties and those prone to bolting can be more difficult to contain indoors. Varieties such as African blue basil, cardinal basil, and cinnamon basil are best grown outdoors.