How does light affect plant growth

Make your garden amazing with these easy to understand tips

how does light affect plant growth

Do you struggle with your garden? Are your flowers looking forlorn and your lawns lifeless? Well, you might not realise it but understanding how light affects plant growth can completely transform your foliage.

Like many gardeners, you might have struggled with enriched compost, fertilisers, and other chemicals to boost your plants but there are some simple things you can do to improve them once you understand how much light is needed.

Read through this post and by the end of it you will have all the information you need to understand how much light your plants need to be at their best.

Why does a plant need light?

Every plant, regardless of the size or type, needs light to survive. Plants use a process called photosynthesis to break down food in the form of nutrients in the soil. Plants get energy to start the photosynthesis process through light and without light the plant would be unable to turn food into energy.

How does photosynthesis work?

The process of photosynthesis is where plants use energy from sunlight or artificial lights to make glucose which is energy. The plant takes in sunlight through the green pigment, called chlorophyll, and then mixes it with carbon dioxide and water to create the glucose. The by-product of this process is oxygen.

What happens if your plant doesn’t have enough light?

There are some key tell-tale signs that show your plant isn’t getting enough light. You’ll notice it start to droop and wilt but some of the most common signs are:

  • Leaves shrivelling and falling off
  • New leaves or buds coming through that are smaller and not as strong as the previous growth
  • Plants may also bend towards the light, for example growing towards a window
  • Leaves bending upwards and curling

You can also have too much light, and you can tell this if:

  • Leaves look pale, dry and will fall off
  • The plant looks worse when it has the most light (so either in the heat of midday sun or when you switch on artificial lights)
  • The leaves might get brown patches

How much light does your plant need?

Most plants come with a recommended amount of light they require as it differs from plant to plant. The way it is described by gardeners is part shade, light shade or deep shade. But what does this mean?

Well, part shade means the plant needs direct sunlight for most of the day (apart from the full midday heat). A lightly shaded area would be underneath a tree or a taller shrub where your plant will get sun all day round but it will be slightly shaded by branches and foliage. A deep shade is defined as somewhere that no light actually gets to the ground. Under a very thick tree or next to a wall that shields the plant from sun would be fine for these plants.

Some plants need “full” sun which is as it is described; this plant should be in full sunlight for six hours or more every day.

How you can make sure your plant has enough light

An easy thing to do is just move your plant into more natural light (providing it is in a pot!) you can simply put it on a windowsill or move it to an area of your garden where the sunlight is for the longest time in the day.

You can also buy specialist grow lights which are designed to give your plant a boost of light on the right spectrum. These are really handy if your house is dark or you live in a climate where there is low daylight at some times of the year. Using these lights, even for just a few hours a day, you can make sure your plant gets enough energy to survive and flourish.

Artificial lights should be on particular spectrums to get the best results. Most purpose-built grow lights have the right colour light but if you’re in doubt you should check it has violet-blue and reddish orange wavelengths as these are proven to give the best results.

You can find out more about setting up your own artificial lights here.


So if your plants are wilting and looking sorry for themselves no matter how much water and food you give them, it is well worth considering if they have enough light.

If your plant has:

  • Fallen leaves
  • Weak new growth
  • Bending leaves
  • Or appears to be growing towards a light source

Check the area your plant is in and make sure there is natural light available or if you can’t get natural sunlight then think about investing in some artificial lights. Once you get the balance of light right for your plant, it should flourish.

If you have any questions, comment below and if you have found this article helpful please share it with your friends.

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