Basil plant under full sun light

How Much Light Does Basil Need?

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Basil is a favorite herb in various cuisines around the world. Yet, they evolved in a tropical setting. Hence, it loves the sun and warm, humid weather. But for how long? What are the limits and exceptions? In this post, we’re exploring answers to these basic questions.

Basil is a member of the mint family, more formally known as the Lamiaceae family. Although they are in the same family, mint can survive shade, while basil can’t.

Yet, there are instances when it’s better to reduce sun exposure. I will discuss these in this post.

What happens when basil doesn’t get enough light?

Some plants love the shade. Herbs like mint, coriander, and parsley can survive shade, but basil can’t.

The first sign is stagnant growth, which is tricky. The plant may grow taller, but this isn’t good growth. This is plants’ natural habit. Plants grow to search for sunlight. In the same way, roots grow towards the water source, too. Yet the plant won’t have healthier leaves and branches. Basil plants with a lack of light would be lean, not bushy.

Crippled leaves of a basil plant that lacks light
Crippled leaves of a basil plant that lacks light

The leaves produced won’t have a nice oval shape. They may look crippled. Also, there will be fewer leaves than there should be. The shape of the plant, too, would be misaligned. With time, the leaves start to lose their color. They become pale green and then yellow.

Some basil varieties don’t show their true nature without sufficient sunlight. For instance, red basil won’t turn red without full sunlight, and most varieties aren’t as aromatic as in full sunlight.

How much light does basil need?

As a plant that evolved in the tropics, basil needs full sunlight, which means at least 6 hours of direct sunlight. If other plants’ foliage covers the basil plant, basil needs about 10-12 hours of light.

Healthy basil plant that grew in full sun light
Healthy basil plant that grew in full sunlight

Basil may still grow in partial shade, but its growth may not be vigorous. In partial shade, basil gets about 2-6 hours of sunlight daily or roughly 10 hours under 50% shade net.

Basil usually stays stagnant under 2 hours of sunlight. They would barely survive.

How to fix insufficient light for basil

Sometimes, you don’t have options. You may need more space in your garden or balcony, where sunlight is scarce. If not, you may live in a country where you only get full sunlight for a few months. You can try a few things to optimize the light basil plants get.

Supplement with grow light

You can grow basil entirely under grow light. Yet, growing lights can also supplement the lack of sunlight. You can turn on the lights when the sun is there and keep them working for about 10-12 hours. Modern grow lights come with timer options. If not, you can buy a timer separately.

Related: A Manufacturer’s Guide To Growing Plants With Lights.

Use reflective material

Reflective material is the best way to make the most of limited sunlight. Use aluminum foil sheets, which you can get from your kitchen. You need to past it facing the sides of the plant. You need to leave the top for the sunlight to enter. And there’s not much use having one under the plant as there are few chloroplasts under the leaf.

Use diffuser polythene

Polythene used in polytunnels has a unique property: it diffuses light. When light enters at least one spot of this polythene, it diffuses and spreads to the entire polytunnel. If possible, build a polytunnel high enough to receive sunlight for most of the day.

Place the plant facing the southern sky.

If you live in a country far north from the equatorial line, your southern sky is more likely to receive more sunlight. If you’re growing basil indoors, place it near the window that faces the southern sky. If you’re growing it in the garden, plant basil at the southern end of your garden.

While this approach works for North America and Europe, if you live in the southern hemisphere, your basil should face the northern sky.

Light for basil when growing indoors

There are various reasons to grow basil indoors. You may not have a garden space or simply like basil’s aroma spreading in your house.

The light that comes from your window may not always be enough. As suggested in the previous section, you can supplement with a grow light. Otherwise, you can install a grow light permanently.

We grow basil for its leaves, not flowers, fruits, or seeds. Thus, most grow lights support basil’s growth. You don’t have to bother about the specific spectrum; you could pick a grow light based on other properties—for instance, a timer and a cooling fan.

High-output LED grow lights usually produce more than 3000 lumens, which is ideal for basil. However, you could also grow basil with T5 fluorescent tubes. Either way, basil plants need 10-12 hours of light to grow well.

When you should provide shade for basil

As mentioned, you can leave basil under full sun for days. But your basil plant is experiencing heat stress if you see the leaves withering. Although it’s rare for basil, it happens.

In such cases, you can install a shade net to reduce the heat the plant experiences. A 40-55% shade net would be more than enough for basil.

Another occasion when you need to provide shade is when you transplant basil from a hydroponic system to soil. The transplanted basil will take some time to adapt to the soil environment. It needs to grow new roots specific to the soil. Until then, you must ensure no water loss. Reducing the heat with shade would help a lot.

Related: How to transplant hydroponic basil into soil

There is a common misconception that seedlings should not be in full sun. But this is wrong. You can germinate and grow basil under full sun with no issues. If this is the case, don’t bother adding shade.

Lastly, if you’ve planted basil as a companion for another plant, you may consider having shade. This is in favor of your companion plant.

Conclusion

Basil needs light, and it needs full sun throughout the year. The more light it gets, the better the plant. This is also applicable to basil seedlings.

But if you happen to be in a situation where full sun is not accessible, you may consider other options we’ve discussed in the post.

Also, there are instances where you deliberately provide shade to basil plants. Now that you know them, your basil will thrive!

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