How to Choose a Grow Light for Indoor Plants and Greenhouses

Plants need light, and a windowsill or a greenhouse doesn’t always supply enough. A grow light can fill the gap, but there are a lot of types and the labels can be confusing. This guide covers what to check before you buy: spectrum, format, power, fitting, length, and where the light will be used.

1. Work out where the light will go

Start with the space, not the product.

Indoor shelves, windowsills and small pots: You need a light that sits close to the plants and fits the shelf.
Greenhouse benches and seedling trays: The light usually supplements the sun rather than replacing it.
A single larger plant or a lamp fitting you already have: A bulb may suit better than a strip.

2. Understand spectrum

Plants use mainly red and blue light for photosynthesis. Grow lights are usually sold in one of two styles:

Broad or full spectrum: These cover a wider range of wavelengths and usually look white.
Red and blue: These use red and blue LEDs only and usually look pink or purple.

Red and blue lights are often chosen for greenhouses, where the plants already get sunlight. Broad spectrum is generally preferred when the light is the only source. Not every light sold as “full spectrum” covers the whole range, so check the spectrum chart if the seller provides one. Many lights also mix chip colours. Look at what the listing says the light contains. If a listing gives no chart, ask the seller.

3. Strips or bulbs?

LED grow light strips are flexible lengths of LEDs that you cut and stick in place. A USB-powered strip runs from a 5V USB source, and you cut it to size, so it suits shelves, trays and small plants.

LED grow light bulbs screw into a lamp fitting. They suit a single point of light over a plant or a corner, rather than a long run along a shelf. Our E27 full spectrum LED grow light bulb has 150 LED chips (100 red, 35 blue, 10 white and 5 infrared) and a 160° beam angle, according to the supplier.

4. Check the fitting before you buy a bulb

Grow light bulbs come with a particular base. Ours has an E27 screw fitting. Many Australian household fittings use a B22 bayonet base instead, and a B22 fitting won’t take an E27 bulb. Check the base on your lamp before you order.

5. Choose the right length for strips

Measure the shelf or tray first. The strips come in 1M, 2M, 3M and 5M lengths and can be cut to length, with a minimum cutting unit of 1cm. Buy a little more than you measure, so you have room to adjust the layout.

6. Check how it’s powered

USB strips run on 5V, so you need a USB power source. A longer strip may need more power than a shorter one, so check the product details before choosing a power source.
Bulbs run from mains power through your lamp fitting. Our bulb accepts 85V to 265V, and the supplier states its actual power consumption is about 30W.

Look for the actual power draw when you compare lights. A headline “wattage” in a title doesn’t always match what the light really uses.

7. Think about moisture and heat

Greenhouses and watering areas are damp. Check whether the product is rated for damp conditions before you use it there, and keep power connections dry. This matters most for mains-powered bulbs. Our bulb has an aluminium shell that works as a heat sink, but keep any light placed so it isn’t touching leaves.

8. Plan the setup

Cut or position the light for even coverage across the plants.
Stick strips to a clean, dry surface.
Switch the power off before you screw in a bulb.
Check each plant’s care guide for how much light it needs. Needs vary by plant, so there’s no single number for all of them.
Watch your plants over the first few weeks and adjust.

Quick Checklist

Where will the light go: shelf, tray, greenhouse or single plant?
Is the spectrum or chip mix stated, and is there a chart?
Strip or bulb?
If a bulb: does your fitting match, E27 or B22?
How long does the strip need to be?
What powers it, and do you already have that?
What is the actual power draw?
Is it suitable for damp conditions if you need that?

FAQ

Can I cut a USB LED grow light strip?
Our strips are cuttable, with a minimum cutting unit of 1cm.

Do I need a power adapter?
USB strips need a USB power source. Check what’s included with the product before you buy.

Will the grow light bulb fit my lamp?
Only if your lamp has an E27 screw fitting. Many Australian fittings use B22 bayonet, which won’t fit.

Are red and blue lights better than full spectrum?
It depends on the setup. Red and blue lights are often chosen for greenhouses with sunlight, while broad spectrum is usually preferred as a sole light source.

How long should I run a grow light each day?
It depends on the plant. Check the plant’s care guide.