Basil is one of the most popular (and easiest) herbs to grow. It thrives in warm, sunny conditions, which means that not everyone can grow it year-round outdoors.
Thankfully, basil is also very easy to grow indoors, whether you keep it inside during the winter or all year long. It does have a few specific requirements, particularly as far as light is concerned, but nothing too difficult.
Here’s everything you need to know about how to grow basil indoors for a bountiful harvest.
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Tips for Growing Basil Indoors
Basil (Ocimum basilicum)
Zones: 2-11 (as an annual, zones 10-11 as a perennial)
Needs: Moist, well-drained soil and full to partial sun
Basil (Ocimum basilicum) is a warm-weather herb that belongs to the mint family. It’s typically grown as an annual because cold weather will kill the plants, but it can be grown as a perennial in a sheltered indoor environment.
To have success growing basil indoors, you’ll need to do your best to replicate its preferred outdoor growing conditions: plenty of light, warmth, and well-drained, fertile soil.
If you are familiar with hydroponics, basil can even be grown without soil as long as you give it the proper nutrients. I personally grow basil in my Lettuce Grow hydroponic stands over the winter. Even basic hydroponics systems, like in a bottle or a Kratky system, can work for basil. Don’t know what I’m talking about? Check out DIY Hydroponic Gardens.
- Baras, Tyler (Author)
- English (Publication Language)
- 192 Pages - 04/03/2018 (Publication Date) - Cool Springs Press (Publisher)
Starting basil from seed is an easy way to get plants going. You can also look for basil plants at a local nursery or garden center. Be patient if you start your basil from seed. They are slow to start and seem to retain their seed leaves for forever. Here are young purple basil plants I’ve been growing hydroponically indoors:
This lemon balm plant, another member of the mint family, was started from seed the same day as the pictured basil. It is substantially larger. Do not be alarmed if your basil grows incredibly slowly for the first month or two.
How to Grow Basil Indoors from Seed
You can start basil plants from seed anytime of the year if you plan to grow them indoors. You may be tempted to grab one fo the little potted plants from the produce aisle at the grocery store, but those plants rarely thrive once you bring them home. Also, you can get an entire package of seeds for less than a single potted basil plant. Starting the seeds saves you some serious money.
To get your seeds started, first fill a seed-starting tray with a good quality seed-starting mix. (Even though you will be growing your basil in pots, it’s a good idea to germinate seeds in a tray and transplant them later.)
If you’re willing to risk the potential for seedling loss due to damping off, try starting your seeds in compost or a compost/potting soil mix. I’ve begun starting my seeds in potting soil mixed with compost and inoculated with endomycorrhizal fungi. Partnering with microbes is an easy way to increase your plant’s yields while decreasing their watering needs (source).
- Promotes Vigorous Plant and Root growth - Improved ability to get nutrients and water uptake from soil
- Decreased amount of watering and fertilization
- Enables the soil to retain nutrients for longer and increase nutrient use efficiency
Basil seeds are tiny and should be planted ¼” deep, max. Cover them with soil and water the seeds well before placing your trays somewhere warm. If your house is cool, you can use a seed warming mat.
Basil can germinate quickly (about 5-7 days) in temperatures of 75-80°F. At temperatures lower than this, it may take seedlings a little longer to emerge, but germination should eventually happy as long as indoor temperatures are close to 70°F.
Once your seedlings are up, place the trays under grow lights or by a very sunny window. I use these inexpensive clip on LED lights for starting seedlings indoors. Be careful to keep the soil moist at all times but not soggy. If you can, run a fan a few times a day on your seedlings to improve air circulation. I use this inexpensive clip on rechargeable fan.
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Choosing Pots for Your Basil
Selecting the right container for basil mainly depends on how much room you have in your house and how big you want your plants to get.
Basil can grow in a pot that’s as small as 4-6” across, or you can opt for one that’s 8” across or larger. Just be aware that the smaller your pot is, the smaller your plants are likely to be because they are limited by how much root space they have.
The photo below is a stock photo, not a personal image. In my opinion, the plant shown really needs a larger pot. If you basil plant looks like this, re-pot it into something larger and it will reward you with more bountiful harvests.
If you plan to harvest a lot of basil, your best option is an 8” or larger pot or several small ones. If you only want to pick it occasionally, you can get away with a small container.
No matter what size container(s) you choose, make sure there are drainage holes in the bottom and a tray or saucer to catch water.
When your seedlings have a few sets of true leaves, they are ready to be transplanted to the larger pots. If you have lots of seedlings, like in the photo below, eat the extra ones as microgreens! They are filled with delicious basil flavor and are perfect for salads, sandwiches, and soups.
If you want to reduce the likelihood of unwanted pests (like fungus gnats), fill your pots with a sterile or soilless growing mix. Ideally, it should have good drainage and some sort of fertilizer to feed your plants as they grow. Fungus gnats can still appear, no matter what soil medium you pick. Use yellow sticky traps to catch them.
- Effective 20 Pack Sticky. Specially designed for flying plant pests. Great for outdoor plant or houseplant.
- Great for attracts whiteflies, fungus gnats, blackflies, thrips, fruit flies, midges and other flying insects.
- Made of ECO friendly materials, safe and Non-toxic, product contain no pesticides and are safe to use indoors and outdoors.
If you can handle the potential for a unwanted house guests, use a mix of potting soil and compost to fill your pots. This will provide your basil with a rich variety of nutrients and should have good drainage. Don’t have compost? No worries! You can find organic compost online.
Unless you have very large pots, plant only one basil seedling per container. Basil can grow large, like in this outdoor grow bag shown below. Over the course of the season, that plant grew 2-3x as tall as what’s shown in the photo. That’s a lot of basil!
Choosing the Right Location for Indoor Basil
Perhaps the most important part of how to grow basil indoors is selecting the right location. Basil needs light and warmth to thrive, which can sometimes be difficult to get inside.
There are two options for getting your basil the right amount of light.
First, you can choose a very sunny window (usually south-facing is best) where your plants will get at least 6 hours of sunlight each day. If you have a sunroom or large bay windows, chances are good your basil will love it there. If your plant looks lanky or pale, it needs more sunlight.
A second option is to use grow lights or a grow lamp. The lights should be kept on your plant for 12-14 hours a day, since they won’t be as strong as sunlight. Be sure to keep the bulbs about 2-4” away from the leaves so they don’t get burned. I use these clip on lights with a built-in timer.
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If you live in a northern area, you may find that grow lights are needed during the winter and a sunny window will work the rest of the year.
Another equally important consideration is choosing a warm spot for basil. It grows best in temperatures that are 70°F or higher and should be kept away from drafty areas. Use a heat mat, if needed, to keep your basil happy during the winter.
How to Care for Basil Plants Inside
Learning how to grow basil indoors is very similar to caring for it outdoors.
Your biggest task will be to water your plants before the soil dries out. Basil doesn’t like soggy feet (overwatering), so you should plan to water only whenever the top 1-2” of soil dries out.
If your potting soil has fertilizer in it, you shouldn’t need to add any more for several months. However, if you notice the leaves of your plants looking pale or growth slows, you can start using a liquid fertilizer about once a month. I personally do not use synthetic fertilizers. Instead, I opt for an organic choice like Fox Farms or Neptune’s Harvest. Go with a “growing stage” product, not a fruiting/blooming stage since you want the leafy growth. Warning: Neptune’s Harvest smells like fish so your cat may become very interested in your basil for a day or two if you pick this option.
Rotate pots that are by a window regularly to help them grow straight instead of leaning toward the light. Harvest or prune regularly to encourage bushy, vigorous growth.
Taking Your Plants Outdoors
You can grow basil indoors year-round, or you can take your plants outside when the weather warms and bring them back in before it gets too cold. Wait until temperatures get at least 60-65°F before taking them out, and get them inside before it drops below 50°F.
Basil isn’t prone to many pests, although it can pick up some of the usuals like aphids, spider mites, whiteflies, etc. Plants outside are more likely to pick up “visitors”, so be sure to debug them before you bring them back into your home.
Harvesting & Pruning Basil
Harvesting fresh leaves whenever you want them is the fruit of learning how to grow basil indoors.
When your plants get several inches tall, pinch off the very top set of leaves. This encourages the basil to bush out— and gives you your very first harvest!
After plants get about 6-8” inches tall, you can start making small harvests. Simply pinch off individual leaves or a set of leaves back to a node. When they get about a foot tall, you can harvest from your plants freely as long as you leave at least ½ of the plant intact.
If you are harvesting leaves often, you won’t need to do any pruning on your plants. However, you will need to snip off flower heads once they appear to keep your plants from flowering and the leaves from turning bitter.
For a detailed look at harvesting your own basil, please see this complete guide to harvesting basil or watch the video below:
Growing Basil All Year Round
Growing basil indoors is a great way to enjoy this herb all year long, but you’ll probably want to start new plants at some point. Even though basil can technically be grown as a perennial indoors, your plants will eventually want to flower, which turns the leaves tough and bitter.
You can allow the basil to flower and cut it back once it finishes to stimulate new growth, but most people find it easier to simply start new basil plants from seed every so often.
For a continuous harvest, plant new seeds every few weeks or every other month, depending on how much basil you like to eat. When one plant fades, take it out of its pot and replace it with a new seedling and new soil.
If you do this, you’ll always have a supply of super fresh basil on hand!
Natasha Garcia-Lopez is an avoid home-gardener and proud owner of 88 acres of land in rural West Virginia. She was a member of the Association for Living History Farms and Agricultural Museums for many years and is currently enrolled in the Oregon State University Master Gardner Short Course program so she can better assist you with your gardening questions.She holds a certificate in natural skincare from the School of Natural Skincare.