growing basil indoors

How To Grow Basil Indoors?

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People grow basil indoors for many reasons. Basil tastes good in dishes and fills the room with its pleasant aroma. Who would hate such a free air freshener?

Yet basil is a plant that evolved in the tropics. It thrives in full sun for at least six hours a day. How would you grow it indoors?

This post will take you through every step for a healthy, aromatic, and flavourful indoor basil plant.

Why would you grow basil indoors?

Although everyone loves the aroma and taste of basil, they don’t have the space to grow. This is one good reason to grow basil indoors. People who live in apartments can use an indoor garden. Indoor gardening has become popular in urban areas where space is scarce.

Basil has a pleasant scent that most people find refreshing. Having a basil plant indoors would fill the room with its aroma. Basil’s aroma is also believed to be repelling snakes and other small insects.

People who live in the Northern Hemisphere experience drastic seasonal shifts. Yet, basil grows well in hot and sunny climates. In winter, they may have to grow basil indoors with proper settings.

Finally, basil repels some insects, but others attack it. Growing indoors protects the basil plant from many such pests.

What is the best method to grow basil indoors?

Basil grows well in soil and hydroponic systems. Thus, you can have a pot with an excellent potty mix or a hydroponic system.

If you’re growing in soil, you must regularly water it. But since basil hates watery soil, you should ensure excess water is drained well, and you don’t overwater it. Once the plant is established in the soil, you can water it once weekly. The plant may still get soil-born pathogens.

Hydroponic basil gets fewer pests and diseases than soil. Also, you don’t need to worry about watering. Basil grows in many different hydroponic systems. For a complete set-it-and-forget-it style, you can choose Kratky. You can thrive in DWC and NFT. All these techniques are compact for indoors and easy to set up.

You can make your DIY hydroponics system. Yet, we recommend a complete herb garden system like the MUFGA 12-pot indoor gardening system. It has several features that are challenging to build in DIY setups and cost less.

How do you provide light to basil indoors?

As a plant that evolved in the tropics, basil needs at least 6 hours of direct sunlight. It thrives in full sun and hot weather. When basil doesn’t have enough light, its growth stops, and leaves turn yellow. Although basil doesn’t die soon, it remains useless, as basil grown in the shade doesn’t give as much aroma and flavor as those that grew in full sun.

The best thing to do for indoor basil plants is to move them closer to a window that receives direct sunlight. But only some can try this. Most people don’t have such a window, and the exposure time is limited.

The next best alternative is a grow light for people who can’t get direct sun for six hours. Since we don’t want the basil to bloom, we can use any light to grow the plant. Yet, grow lights are made to concentrate the light only on the plant. Generally, lights are made to disperse rays throughout the entire room. Thus, it’s beneficial to grow basil under a grow light.

If you’re supplementing or growing altogether with a grow light, we suggest 10-12 hours of light for basil. For grow lights, we suggest Barrina’s T5 LED grow lights, which have been tested and are trusted by many.

Steps to set up a hydroponics System to grow basil indoors.

Basil is a resilient plant that grows in many different systems. In this section, I’ll outline how to set up a DIY hydroponic system to grow basil indoors. We’ll discuss the DWC technique. We assume you’ve already propagated your basil plants.

Related: How to propagate basil from cuttings

Step I: Choose the container.

To set up a DWC system, you need a container high enough to support basil’s root mass. Hydroponic basil tends to grow many roots, which could grow for more than two feet. Yet, you can root prune basil and keep it dense and short. Root pruning has several other benefits, too. Also, in small containers, basil may develop root rot conditions.

Related: Fixing Root Rot in Hydroponic Basil

If you’re growing more than one basil plant, the plants must be at least a foot apart. Although there’s no competition for nutrients in hydroponics, there is for the light. Further, basil may catch infections like powdery mildew when the leaves are too dense.

Related: Hydroponic Basil Pests and Diseases

The container must not be transparent. Transparent containers will develop algae sooner than nontransparent ones. Black containers are ideal because they don’t let light in. White is good as well because it reflects most of the light. Cover the container with an aluminum foil sheet if you have neither white nor black.

Step II: Choose net cup size and drill holes

Basil can grow up to several feet high, but it can also be harvested when only about 6-8 inches high. The problem is that if your primary plant gets too big, smaller net cups won’t be able to hold it right.

Netcups of about 2 inches in diameter are ideal for basil.

But this is not a hard and fast rule. Some basil varieties, like the holy basil, grow more prominent. But the most common, sweet basil, grows only to a maximum of one or two feet in height.

Now, we come to the point where we drill holes. Use a hand drill to pluck the holes. As mentioned, basil must be at least a foot apart. Also, leave enough padding to prevent the plant from falling outside the container.

Step III: Prepare the nutrients

Most basil varieties grow well at an EC of 1.5-2.5. You may start at 1.5 and slowly increase the EC to 2.5 as the plant grows. Yet, mature plants can even grow at 3.5 EC. Also, it’s best to keep the pH at around 6.

The best way to mix nutrients is to have an EC and pH meter.

Hydroponic nutrients come in two parts. That’s because heavy metals tend to precipitate at high concentrations. So, you need to dissolve and dilute parts A and B separately. Then, mix them in your nutrient reservoir in equal amounts until you get your desired EC.

Yet, there are also one-part and multipart solutions. The single-part solution contains chelated micronutrients that do not precipitate and are costly. It would be ideal if you start hydroponics for the first time or grow on a small scale.

Multipart solutions are too complex to mix. They are for industrial-scale growers who need precision at the lowest possible cost.

Coming back to the two-part solution, part B is always calcium nitrate. For Part A, you can use any water-soluble NPK fertilizer with micronutrients. In the US and Europe, you can use master blend 4-18-38 as part A. Campbell Diamond Special T works well for part A if you’re in Australia.

It would be best not to fill the container with nutrients at the top. In DWC, you wet the roots with nutrients when air bubbles burst on the reservoir’s surface. So, leave about 4-6 inches from the top and fill the rest with your nutrient solution.

Step IV: install an air pump.

As mentioned in the last step, we wet the plant’s root with nutrients with the splashes when air bubbles burst in the reservoir’s surface.

You need an airstone and an air pump. Ordinary aquarium air pumps will do this job. Connect the air stone to the pump and place it at the bottom of the container. You should see water bubbles bursting at the surface and splashing nutrients outside the container. If you can’t see the splashing water rise high enough, you may need a bigger pump or a different air stone.

You can now close the container’s lid with the holes we put for the plants.

Step V: Transplant the seedlings.

We assume you already have basil seedlings to be transplanted. You can either start basil from seeds or cuttings. Basil accepts a wide range of growing mediums but loves the ones that can drain water fast. Jiffy pallets would be ideal for growing basil in most systems.

Put the seedlings in a net cup and place it in the system we created. As we measured the hole size already, it should fit right if it doesn’t poke a hole in a styrofoam sheet and place it between the container’s lid and the net cup. It should hold tight now.

Step VI: Install lights

If you think it’s done once we transplant seedlings into the system, you’re wrong. As we said, you don’t need this if you have a window through which the basil plant can enjoy at least six hours of light. Others need to set up a light to supplement or replace sunlight.

Build a small structure to hold the lights above the plant. If you keep the setup in a rack, you can use the shelf above to hang the lights. Make sure there’s a 6-inch gap between the grow light and the tallest plant’s topmost leaf. Placing the grow light too close may burn the plant, and placing it too far would not be efficient.

You can use regular T5 fluorescent lights as grow lights, but proper grow lights are made to concentrate their output on the plant. They also come with specially designed fans and heat sinks.

You must keep the lights on for at least 10-12 hours daily, regardless of whether you have partial sunlight.

Step VII: Install a fan (Optional)

Basil, like any other plant, needs enough airflow to grow well. Airflow helps the plant’s transpiration process; more air means more nutrient uptake.

When there’s not enough airflow, the first sign you’d see is that the tips of the older leaves burn. This is because calcium can not be transferred to the top of the leaves.

Install fans to provide ventilation. You don’t need fancy fans; regular fans we use at home would do.

When to harvest basil?

Basil typically can be harvested every two weeks once we start the initial harvest. The initial one can be done when the plant is at least 6-8 inches tall. Cutting the basil stems every time you harvest would be better than picking the leaves. This process stimulates growth. Also, you must ensure at least one or two sets of leaves in each stem before you cut. New branches will form near each of these leaves.

How to prune basil with pruning scissors

Related: How often can we harvest basil?

Common issues when growing basil indoors

Basil is a relatively easygoing plant. Yet, it isn’t immune to all diseases and pests. Like many other plants, it could get leafminer attacks and powdery mildew. Most of these problems are a concern for outdoor growers. Growing basil indoors, in fact, has the benefit of fewer problems. Here are a few things you should take care of.

1 Stunned growth

There can be many reasons for slow growth. Basil thrives in hot and bright climates, so lack of sunlight can be one reason. You may also need more nutrients in your reservoir. Regularly check the EC levels and adjust them if needed. Stunned growth can also be a first sign of root rot.

2 Leaves turn yellow

Yellow leaves are mostly a sign of nutrient deficiency and stunted growth. If yellowing starts with older leaves, it’s probably nitrogen deficiency. Yet, if younger leaves show interveinal bleach, it means iron deficiency, which is very common in hydroponics. Applying foliar spray could heal the situation.

3 Root rot

In hydroponics, if you see slow growth, you can lift the plant and check if the roots have rotted. Rotten roots are generally dark in color and produce an unpleasant odor. In hydroponically grown basil, this odor may not be significant. Root rots are rare in aerated systems like DWC or recirculating systems like NFT. But they can happen.

4 Tip burning

Insufficient airflow causes tip burns. The plant needs wind circulation to help with its transpiration process. Without airflow, the plant will have difficulty bringing calcium to the tips of the leaves, which is essential in producing cell membranes. Thus, a lack of calcium would show up as tip burns. You can install a fan and fix this problem.


Basil is an aromatic, flavourful herb and an easygoing plant. Those who don’t have the space or other specific conditions outside choose to grow basil indoors. Few grow basil for its ornamental properties and aroma alone.

In this post, we’ve discussed growing basil indoors using a simple DWC hydroponic system and some issues you may encounter. Although this issues list isn’t complete, these are the most common.

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