How to Grow and Care for Basil Indoors

Basil is one of the easiest herbs to grow indoors. With the proper conditions, basil grown indoors can be just as successful as plants in the garden—without fearing that insects or critters devour the plants.

It is possible to plant basil indoors at any time of the year, either by starting it from seeds or buying a potted basil plant at the supermarket.

Can You Grow Basil Inside?

The key to successfully growing basil indoors is light. As with many other herbs, basil is a true sun-lover—place it near a sunny, south-facing window where it gets six to eight hours of bright light every day, and it will thrive. Alternatively, basil does exceptionally well under grow lights.

Basil is easy to grow. It requires little maintenance other than watering and fertilizing. It is also relatively pest and disease-free. It's a compact plant that easily fits on a windowsill in even the smallest apartment space.

How to Grow Basil Indoors

Growing basil indoors is not much different from growing it in your garden.

Sunlight

Whether it is grown indoors or outdoors, basil plants need ample light—at least six hours of full sun daily.

Artificial Light

If you're using fluorescent bulbs, keep your basil under them for 12 hours a day, with the lights about 2 to 4 inches away from the top of the plants. Be careful not to let the leaves touch the bulbs to prevent burning.

Temperature and Humidity

Keep your basil somewhere in your home that has an average temperature of 70 degrees F or higher. Avoid putting the plant anywhere it may be subjected to a harsh or cold breeze, like in front of an open window in the winter or near an air conditioning unit. Basil plants also like a fair bit of humidity, so mist your plant occasionally, especially if your home is particularly dry. If you find you need an added bit of moisture, place your basil container on a bed of wet river rocks to increase the ambient humidity around the herb.

Watering

For best results, aim to keep your basil plants regularly moist. Basil thrives when it receives about 1 inch of water a week, but plants housed in containers often need a bit more than that. Water your plant once the top layer of soil has dried out, or when the plant shows the first signs of wilting (though it's best to not wait for that as a signal).

Fertilizer

Because basil is harvested on an ongoing basis, it needs a small amount of fertilizer to keep producing its delicious leaves. Use a complete liquid fertilizer, diluted to half strength, once a month. If the plant is not growing much, temporarily increase the fertilization to twice a month.

Pruning and Maintenance

Basil is a carefree plant that needs little maintenance. Well-drained soil, good air circulation, occasional watering, and plenty of sunlight are enough to keep a basil plant in good shape. 

The plant responds well to pruning, but don't expect indoor plants to get quite as large as those grown outdoors. Pinching a young plant encourages more leaf growth. As the plant is established and has branched out, regular harvesting of your basil doubles as pruning. Always harvest leaves from the top down. Cut off individual leaves from smaller plants, or snip stems a few inches down for larger ones.

Container and Size

To avoid root rot and other fungal diseases, basil needs a container that allows for good airflow and excellent drainage. A 4-inch pot is usually large enough for a basil starter plant.

Potting Soil and Drainage

Basil needs soil that is moist but well-draining. For best results, amend high-quality potting mix with a few tablespoons of organic compost. Select a pot with large drainage holes at its base so the soil doesn't get soggy or waterlogged.

Potting and Repotting Basil

If you started basil from seeds, transplant the seedlings from the seed starting tray to a 4-inch pot filled with potting mix and compost. Usually, basil reaches the end of its annual life cycle before it needs repotting. However, if the roots have filled the container, or grow out of the drainage holes, the plant needs repotting into a larger container with fresh potting mix.

Moving Basil Outdoors for the Summer

Only move your basil plant outdoors in the spring when nighttime temperatures are consistently above 50 degrees F. Its leaves start to blacken when the temperature drops below that mark. Basil is a cold-sensitive plant—it does not take a frost to damage it.

Considerations

Gradually adapt the plant to outdoor conditions, similar to the way you harden off seedlings before you move it outdoors for the duration of warm summer weather.

Outdoors, your basil plant needs more frequent watering than inside. Water it daily in the absence of rain.

When to Bring Basil Back Inside

At the end of the summer, or in early fall, depending on your climate, bring the plant back inside when temperatures drop below 50 degrees F; don’t wait until the first fall frost hits. If the days are still warm but the nights are cold, bring the plant inside just for the night.