How to Grow Plants with Grow Lights Successfully

If you are looking to grow plants indoors under grow lights because you either have limited outdoor space, lack of a sunny window sill or just want to give your plants a boost, then supplementing them with plant grow lights could be a good option for you.

There are many types of grow lights available, ranging from the more commercial and high output units such as high pressure sodium (HPS), Metal Halide (MH), which are grouped in the High Intensity Discharge (HID) grow lighting category, to the more user friendly and more domestic fluorescent grow lights, CFL grow lights or LED grow lights.

What type of grow light do I need?

Deciding which type of grow light you need is the first step when you are thinking of purchasing a grow light for plants.

If you have lots of plants and are growing commercially then you will probably be better off with the HID type lights, like the metal halide growing lights and the high pressure sodium grow lights.

However if you are thinking of growing your own chillies, herbs and other plants indoors, then you will be probably want to start with a fluorescent grow light, CFL (compact fluorescent grow light) or LED grow light.

I’ve heard that plants need both white and red spectrum light to grow properly…

Whatever type of grow light you choose, it is important to realise that plants need 2 main types of light to grow. They need light in the white/blue spectrum for the vegetative and propagation stages of growth and light in the red spectrum when it comes to flowering and fruiting, which you can switch to at the appropriate time.

For example if you are growing plants under HID lights, then you could use a metal halide grow light to provide white/blue spectrum light to your plants for the propagation phase and then you could switch to a high pressure sodium grow light to provide your plants with the red spectrum lighting that they will need more of when they start flowering.

If you are using fluorescent grow lights, then you can easily swap out your growing bulb or tube from the white/blue type to the red spectrum type economically using the same grow light fixture. LED growing fixtures also are available with blue and red LEDs, or a mixture of both types to create a more all round light for growing plants.

What are the advantages and disadvantages of each type of grow light?

Again, it depends on your application. If you’re growing lots of plants commercially or in a greenhouse, it is difficult to beat the power output of HID type grow lights and both the white/blue MH grow lights and red HPS grow lights can provide high outputs of light for this application.

The main disadvantages is that they are relatively costly to run, heavy, are somewhat noisy, dependent on the type of ballast (transformer setup) they use and they also run very hot, so you will need a lot of ventilation and also make sure that your plants are far enough away from the lights as they can scorch the leaves if too close.

Fluorescent grow lights, including compact fluorescent grow lighting is more suited to indoor locations as the units are often more compact, lighter and are more efficient and produce a lot less heat than traditional HID grow lights, making them safer and more convenient for indoor use.

One of the possible downsides to using these types of light, is that although they are more economical, the amount of light produced does not match that of the HID units, however if you are growing chillies or other herbs indoors, then you will find that these units work perfectly well and can produce some great results, making them ideal for growing indoors.

LED grow lights are relatively new, but as you may well know, LEDs (Light Emitting Diodes) produce a lot of light for the amount of power they consume and they are getting brighter and brighter as the technology develops.

LED grow lights run cool so you can position your plants closer to the lights for maximum benefit.

A unique benefit of the LED is that they can produce very accurate wavelengths of light within the desired range that is best for growing plants, so less light is wasted - that’s why you see LED fixtures that are equivalent to higher output alternative bulbs or lamps.

One disadvantage is that they are more expensive and you may need a larger fixture or more of them if you have lots of plants, but on the plus side you will make savings on your electricity bill and they are lightweight and can produce some impressive results.

I’ve heard about all round grow lights – are they any good?

It depends on what you are trying to achieve. If you are growing commercially, then you will be better off changing from the relevant white/blue type bulb to a red spectrum bulb when your plants start to flower for best results. These types of bulbs are so high in output that they can supply the demands of your plants easily all year round.

However, if you are looking to grow your own chillies, cooking herbs or give your plants a boost indoors, then going for a fluorescent grow light with a white/blue fluorescent propagating bulb, which is often supplied with these fixtures, is a great way to start.

The white/blue type bulbs are great all-rounders and can help provide your plants with a good boost during the propagation and vegetative phases of growth, and during the colder months where there is less sunlight.

Giving your plants a boost during the colder months is especially useful if you want to improve your harvests of chillies for example, as a bigger plant will often yield more chillies!

When it comes to flowering and fruiting, you can still continue to grow under the white/blue type bulb, but for minimal cost you can just swap the tubes or bulb for a red propagating fluorescent tube, which will produce much better results.

One thing to note however is that although the white/blue propagating bulbs are great, the red spectrum tubes are no match for sunlight, so if you have an outdoor space, a sunny window sill or a greenhouse, then it is best to move your plants outside when the whether improves.

If you haven’t got any outdoor space or a sunny windowsill, then you can still grow plants all year round indoors using the lights, just make sure you go for a unit that is powerful enough to get the job done, such as a 4-Tube high output T5 fluorescent grow light like the 4-Tube LightWave T5.

So if you are planning to give your boost during the colder months or grow herbs indoors then you a 2-tube high output t5 fluorescent grow lights like the 2-Tube LightWave T5 is a good place to start, and if you have more plants or want to grow plants all year round indoors then a 4-tube t5 fluorescent grow light is a good choice.

There are larger fluorescent grow light units available, but if you are growing lots of plants, you can then decide between fluorescent lighting and HID lighting.

So you have decided on what grow light you need, what next?

Great, soon you’ll be able to start growing. The next thing to think about is getting some grow light hangers so that you can easily mount your new grow lights in a suitable place.

Most grow light hangers are adjustable so you will be able to closely position your grow lights near the top of your plants.

Fluorescent grow lights can be positioned much closer than traditional style grow lights as they run much cooler, but it is important to closely monitor your plants when you move the lights closer and always leave a suitable gap. If you notice any negative effects, then move your lights up immediately. It is therefore best to start off with your lights higher than they need to be and slowly lower them to find the ideal position.

Another part of successfully growing plants indoors with grow lights is how long you have your lights turned on. For this, you will need a grow light timer to control the hours that you’re the lights are on.

Make sure you get a timer that has a higher rating than the lights you are using, as if it is not rated high enough, then the relay that turns the lights on and off may stick and this can cause a build up of heat, which can be dangerous. If you are using fluorescent grow lights, then a simple household timer can be effective (but make sure it is rated high enough for the power consumption – higher is better).

If you are using HID grow lights, then make sure you get a grow light timer that can handle the power requirements of these units. Most household timers are not suitable for this application, but they are readily available, just check the wattage of your unit and buy a timer than can handle a bit more than this.

How many hours do grow lights need to be on?

Depending on the time of year and also when your plants start to flower, you will need to adjust the amount of hours your grow lights are on.

Do not leave your grow light on all the time as plants need to have darkness as well in order to grow properly.

If you are propagating or giving your plants a boost during the colder months, then 14-16 hours a day on and about 8-10 hours off is about right.

When your plants start to flower, then you can reduce the amount of hours to about 10-12 hours on and 10 to 14 hours a day off.

So now you know, you can grow!

You should now have the knowledge to make an informed decision on the type of grow lights you need, how to set up your grow lights and how long to turn them on for, as well as when to change the bulb, so now all you need to do is turn on the lights and start growing!

For fluorescent grow lights, replacement t5 fluorescent tubes and grow light hangers, visit our Fluorescent Grow Lights page.