Bonsai Grow Lights

Grow lights are a strange topic in bonsai. Some people swear by them and other people see them as the enemy, others do not even know they are an option.

In this article I will be looking at grow lights and how they might help you and your bonsai.  

What Is A Grow Light?

A grow light is a special kind of light that is used to grow plants. They are very common with cannabis growers, but they can be used to grow any type of plant, including bonsai.

Are Grow Lights Different To Normal Lights?

Yes, grow lights are very different. A normal light emits a small spectrum of light, basically just visible light. Which is exactly its purpose, it provides light so that we can see.

A plant needs a lot more than this small spectrum of visible light to grow. The sun emits a huge spectrum of different lights and the plants use a lot of these to grow. (Think back to your physics class – Infra Red, UV light, Visible light, etc)

Basically a grow light emits a much broader spectrum of light. They are designed to cater for what the plant actually needs. They will often produce a lot of light in the red and blue spectrums, which is the optimum type of light that a plant uses in the photosynthesis process.

Sun light is still the best light source for a plant, but a grow light will produce a lot of the type of light a plant needs.  

What Type of Grow Lights Can You Get For Bonsai?

The two main types of grow lights are fluorescents and LED lights.

Both types have their pros and cons.

In general, fluorescents can produce a wider spectrum of light and are generally cheaper. However, they often get very hot and can also be quiet expensive to run. They take a lot of energy, so your electric bill can be quite high.

LED lights usually cost a little more to buy, but they last longer and perform more efficiently. You will find they tend to actually cost cheaper in the long run as they last longer and are a lot cheaper to run.

I have two LED Lights for my bonsai. One from Mars Hydro and one from Plant Photonics

What Light Spectrum Does A Bonsai Need?

When you look at the description of any grow lights it will talk about the light spectrum. You want it to say “Full Spectrum” this means it will cover everything that a bonsai needs to grow.

You will also see white or red grow lights. This difference isn’t too important for growing bonsai trees. It’s argued that the lights with more red help with better flowering, which doesn’t really concern us as tree growers. This is something for cannabis growers to worry about.

So long as the light is full spectrum, it will be fine for a bonsai. I have used both colours and have found both to be excellent.  

What Does The Watt Of A Grow Light Mean?

Grow Lights will also be labelled as having different levels of watts. Basically the higher the watts, the more powerful the grow light is.

It all comes down to how much electricity a grow light can take… or something like that. My school physics classes have been long erased from my memory and I don’t think is too important, but a lot of people get hung up on this and really worry about what Wattage grow light to buy.

The issue is that a lot of lights just lie about the wattage. They will say one thing, but when they are tested (by people who know about this stuff), they are actually way lower than advertised.

You’re probably just better worrying about what you can afford and what size of a footprint the grow light will cover. Usually the bigger the wattage, the bigger the area that the light covers (as a very general rule).

Reading reviews of the grow light and seeing that you can get results is more important that understanding the wattage.  

How Much Do Grow Lights Cost?

The cost will be based on a number of factors. Basically the higher quality and more powerful the grow light is, the more expensive it will be.

You should try and avoid the really cheap grow lights you can buy on Amazon and should aim for something a bit more expensive. A lot of these really cheap grow lights do not actually do anything, you may as well just use a normal light and as I’ve already discussed, that wouldn’t be adequate for the bonsai needs.  

You don’t need to go fully high-end, but a quick bit of research will show you the rough price of a useless Amazon light and a genuine good quality budget light that will cover your needs.  

(If a light is like £30 it’s probably useless.  Anything decent starts around £100… But do your own research so you are satisfied you’re buying something effective, as price alone is not a clear indicator of quality.)

Setting Up A Grow Light For Your Bonsai

Where ever you decide to place a grow light, you should try and box it in. They emit very strong light and it can be almost blinding.

I would recommend you buy a grow tent to contain the grow light, or at the very least build something out of cardboard to surround the light to try and keep the light from spilling out everywhere.

I did this with one of my grow lights. I used Mylar survival blankets to line the cardboard (those foil blankets see every one wrapped up in at the end of a marathon). This is far from perfect (its looks so ghetto) but it does reflect some of the light back in towards the trees and more importantly its stops the extremely strong pink light form filling my room and blinding me.    

Heat Risks Of Grow Lights

You need to be careful with some grow lights. They can get rather hot. You need to be even more careful if you are going to surround them in cardboard.

The first issue is burning your house down. Please don’t do that! So make sure you light still has plenty of air getting to it and isn’t touching anything and has plenty of space around it.

Some grow lights will get hotter than others. This is totally dependent on the type of light and the model you have bought. Just be aware that some can get very hot.

The second issue with this that the heat can affect the bonsai trees you are growing. Usually a bit of heat is fine and actually beneficial for the trees, but you should just check that it is not becoming so hot that it is detrimental to the bonsai trees.

You should try and keep everything well aerated for optimum health. Usually a small fan can sort this out.

How Long Should You Keep Your Bonsai Grow Lights On For?

This is totally dependent on what you are growing and when. As a general rule you shouldn’t keep the light on 24/7. You should get a timer and make sure the bonsai receives some darkness each day.

I like to find out where my bonsai trees grow naturally, then look at the climate for that area and set the timer to be the same as the average day lengths in this area. This is generally a good starting point to work out how long you should keep your light on for.

This is also how I work out how to change the light throughout the year. This does take a lot of work as the timers are manual and they will need adjusted every few days to slowly increase or decrease the light levels throughout the seasons.  

This makes my trees feel more like they are in their natural environment and gives them a more natural rhythm to try and keep them as healthy as possible.

(You can read more information about – How To Grow Bonsai With Grow Lights)

Why Should You Get A Grow Light For Your Bonsai?

Using a grow light for bonsai should really be the last resort. You should always try and grow naturally if you can, but depending on your climate and the species you are growing it may be beneficial to get a grow light.

Having a grow light means you can control exactly how much light a bonsai tree gets. This will usually mean you are able to give the tree more than it would get in your natural environment.

I got a grow light as I had a number of succulents and tropical plants that needed to stay inside to make sure they were kept at the right temperature.

However, when I moved house I lost my perfect big south facing window that had been keeping everything well lit all year round. Now my indoor bonsai trees where basically sat in the dark and they were really starting to struggle and they would have definitely died if I had left them.

I bought the grow light so I could give them the light they needed, while still keeping them at the right temperatures inside.  

Using a grow light is a lot of work, but I have found it invaluable. It has stopped my bonsai trees from struggling and they are now growing far stronger than ever before.  

(If you are thinking you might need a grow light you should read – Do You Need A Grow Light For Your Bonsai)

What Bonsai Trees Should You Use With A Grow Light?

Not all trees are the same, so it makes sense that their light requirements are not all the same. This means some trees will be more suitable for a grow light than others.

Tropical bonsai Trees And Grow Lights

This is probably the most sensible option. Tropical bonsai trees obviously come from areas that have longer, sunnier days.

A grow light is very easily going to be able to replicate this compared to your own climate, especially during the dark winter months and it will give you full control how much light they get. 

A grow light is really going to help a tropical bonsai tree reach its optimum growth levels.

(Read my guide on what the Best Trees For Indoor Bonsai are)

Native/Temperate Bonsai Trees And Grow Lights

These should really just be left outside. It’s very likely that they can survive in your climate and the light levels you receive will be more than enough.

You can certainly grow these bonsai trees under grow lights. They will grow like crazy as you can push them to their optimum levels.

However, these type of trees need a winter period and you will have to adjust your light levels accordingly. The real issue is that if you are using a grow light, you will have your trees inside. This means you need to be able to control your temperature and be able to drop it for the winter months, which is quite hard to achieve inside.

This is why growing these bonsai trees inside and under grow lights is problematic and you should just grow them outside to make your life easier.   

Seedlings and Grow Lights

 If you are starting seedlings to grow into bonsai, a grow light gives you a lot of flexibility and control.

With a light you can start them at any time of the year. Once they germinate you are able to give them the optimum levels to really get them going and make them as strong as possible.

The biggest issue is that you need to be careful not to give them too much light, or keep the light too close to them. Seedlings are delicate and can easily be damaged by giving them too much light or heat.

Conclusion

Grow lights are not really essential for bonsai, especially if you are focusing on trees that are native to your area and can survive outside all year round.

If you have a bonsai tree that is kept inside, you will probably find that a good sunny window is sufficient for its needs.

However, grow lights are available and can be used for bonsai.

They take a little work and should really only be used in certain conditions, but perhaps you may benefit from one as they really are a useful tool in your trees development.