7 Tips For Using LED Indoor Grow Lights

Growing plants, whether flowers for the garden or vegetables and fruit, often begin indoors with seeds or seedlings. Different seeds need differing temperatures and conditions in which to germinate, and some plants grow better with more or less light or heat. There’s a lot to be learned for the novice gardener, and even experts learn new things every day. You don’t need a lot of space to start growing from seed – or even from seedlings – but you do need to recreate certain conditions.

A greenhouse or glasshouse is a great idea, but in winter it becomes less productive. This is why many gardeners are now growing indoors. A spare room or a basement can be a great place in which to grow plants before potting them on or planting them out, and thanks to LED lights, there is now a method of cultivation that is easy to use, affordable, and very effective. Indoor grow lights are useful for growing salad plants in winter, for example, so you can sow all year, but what are they, and why are we suggesting you use LED?

LED lights use very little energy compared to other types of light. They also give off very little in the way of heat. Furthermore, they are available in different ‘colours’ of light – the wavelength that may differ for various light fittings – and are far easier to control than standard lights.

You can check the RHS advice on artificial lighting for further details, but for now, let’s have a look at some handy tips that will help you get the best out of your LED grow lights.

How to Use LED Grow Lights

As we said above, one of the most advantageous aspects of using LED grow lights is the controllability. These lights give out a constant light and can be bought at various power levels so you can decide which is the right one for your plants. Here are some important tips to remember when you start using LED grow lights for your indoor growing.

How to Use LED Grow Lights

1. Get the Height Right

Each of these areas of advice may differ for specific species. To make things simpler, we are giving you the general advice for growing common garden plants from seedling indoors. One very important factor to consider is the distance of the light from the plant. You should remember that while LED gives off very little heat, too close can still burn and damage the plant.

For a standard wattage – we’ll come to that in a moment – you should begin with the light at least 300mm from the plant itself. Once the plants begin to establish, move the light away from the plant, and when it starts to become a healthy adult plant, 600mm may be sufficient. You may find better and more specific information from growers online, and we recommend you check them out.

2. Blue and Red LED

It is important that the lights you use emit ‘blue’ or ‘red’ LED light. This is light that falls within the measured wavelengths that allow plants to grow. Look for LED lights within the spectrum 400 to 700nm – the measurement unit for light emission – as it is within this range that photosynthesis is encouraged, and plants will bloom.

3. The Right Wattage

In addition to getting the right wavelength and keeping the lights at the ideal distance, you also need to keep an eye on the wattage of the lights you use. This can be anything from a 60-watt low power LED to upwards of 240W, with the latter being used mainly for commercial growth. Check out forums and growers online and ask around at your gardening and growing retailers as they will advise you for the right sort of light for your plants.

4. Give the Plants a Break

Some growers have lights on the plants 24-hours for constant growth, but many advise that a plant should follow its natural cycle and involve a ‘night-time.’ This is where you turn the light off and leave the plants in darkness, usually for around 6 to 8 hours at a time. This will be long enough to ensure the plant gets a day and night cycle that it will respond to.

5. Keep the Heat right

Different plants require different levels of heat in which to grow, and this is again something that you should ask around and get the right info on. As LEDs do not give off much heat, it is important your seedlings are heated by other means – controlled electric heating is recommended – so that they grow and flourish as they should. Don’t use the LED for heat as it will not be sufficient and remember to modify heat levels if you are growing through the winter.

6. Experiment

We don’t mean go wild, but if you follow all the tips given by growers and others and things are not happening, try a few changes: move the lights slightly nearer or add an extra couple of hours – or go the opposite way. Some plants just refuse to behave!

7. Food and Water

Don’t forget that even though your plants are growing under lights and indoors, they still need the nourishment and water that they would be growing in the glasshouse or the garden, so keep them fed and watered!


LED grow lights are an effective and affordable way of growing plants indoors and in winter, and you will find that you get the hang of it in no time if you follow the advice here and elsewhere.

Vera Watson

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