Email us   -         Call us   -   01926 511151

The Horticulture Company guide to grow lights

Read our Guide to LED Grow lights here


Sunlight has a wide spectrum and plants have to use a specific window of the wavelength range of light (400 - 700 nanometres) in order to carry out photosynthesis. This wavelength window is known as Photosynthetically Active Radiation (PAR for short), and it’s this range of the light spectrum that you need to replicate in order to mimic sunlight and provide the perfect environment to grow great, healthy crops. Photosynthesis is the process by which plants convert light energy into the essential sugars they need to grow and thrive. 

In the world of horticultural lighting you are likely to come across the words ‘lumens’ and ‘kelvins’. These are measures of how much ‘plant usable light’ a grow lamp will provide. Kelvins are used to measure blue light (Vegative and Propagative) and lumens are used to measure red light (Flowering/Fruiting). The more lumens or kelvins a grow lamp has, the more plant usable light it gives out.

Plants have three main stages in their growth cycle; the propagation stage, the vegetative stage, and the flowering / fruiting stage. Different spectrums of light are suitable to different stages of growth. Therefore, it’s highly important that you use the correct lighting for each of these stages to ensure your plants are growing to the best of their ability.

The propagation stage

Whether you plan to grow from seed or use cuttings, the propagation stage is always the first stage of the growing cycle. During the propagation stage your plants will be busy forming roots and building a solid foundation on which to grow and flourish. As you can expect, this is an extremely important stage of your plants’ life and getting the lighting right makes all the difference.

During propagation a light source needs to be placed as close as possible to your plants. This will ensure they don’t grow flimsy, spindly stems reaching for a light that’s too far away.

Propagation requires less light energy than that required in the other stages of plant development, propagation lighting outputs little heat and can be can placed close to your plants, ensuring healthy and sturdy growth.

The vegetative stage

After propagation plants move into their vegetative stage. This stage of the plant life cycle is where your plants will be carrying out photosynthesis, growing new leaves and building the foundations needed to ensure a productive flowering/fruiting stage.

During the vegetative stage plants utilise the blue spectrum of light, which, in a natural setting, would be adequately provided by the summer sun. 

Metal halide HID lamps give out the correct blue light spectrum needed to ensure healthy plants during the vegetative stage. We sell metal halide lamps from a range of well known suppliers.

The flowering / fruiting stage

Once your plants are ready to enter the flowering/fruiting stage,  it’s mainly light in the red wavelength that is needed. This red light replicates the sunlight your plants would naturally be exposed to when flowering during the late summer / autumn months.

Sodium HID lamps give out the correct red light spectrum for optimum plant performance during the flowering / fruiting stage. We stock a range of sodium lamps that provide good quality, reliable and consistent results.

Dual spectrum lighting

As well as lighting that puts out wavelengths specifically tailored for the vegetative and flowering stages, manufacturers also make grow lights that are dual spectrum (red and blue) which can be used continuously during both of these stages.

Dual spectrum bulbs are effective and work perfectly well at obtaining great results. It is evident that they still don’t produce the same yields when compared to using bulbs specifically designed for the vegetative and flowering stages but do offer an easier and more manageable method for beginners or hobbyists.

We’ve carefully selected our range of dual spectrum grow lamps as they provide the best output possible to cater for both the vegetative and flowering stages. 

Overall, if you’re on a budget when purchasing grow lights then buying a dual spectrum bulb can help you save money. But, if you’re dedicated to getting the best results possible then we still recommend using lighting that’s specifically designed for each stage of your plants’ growth.

HID grow lights

HIDs were the original lighting solution on the horticultural market, and to date, they are still the most effective. When used in the right sized environment, the correct HID light will provide great light intensity that penetrates the entire growing space, helping plants stay healthy from the bottom of the stem to the tip of the highest leaf.

HID grow lights need a ballast to operate and are available in a range of wattages, from 150W all the way to 1000W of power, meaning they can be used in practically any sized growing environment.

CFL grow lights

CFL Grow lights are available in 125W and 250W of power, making them ideal for smaller indoor growing environments. Overall, CFL lights use less energy and produce less heat than HID lights, but they don’t generate the intensity of light that can be achieved with their HID counterparts, which means overall yields aren’t quite as good with CFLs when compared to HIDs of the same power.

Nevertheless, HID lights can generate too much heat in confined growing environments and when this is the case, CFLs are a more practical solution.


The higher the wattage of your grow light, the more power and light you’ll be supplying to your plants. Iincreasing the light to your plants increases the photosynthetic energy available, which in turn increases your chances of getting a great yield. For example, a 600W and a 1000W grow light used in the same sized space under the same conditions will get different results. The 1000W light will outperform the 600W light because it produces a greater output, therefore increasing the amount of light energy available to your plants. 


Reflectors do exactly that; they reflect the light from your grow lamp around the growing environment to ensure light is dispersed evenly and you maximise the overall area your grow lamp can cover.

Reflectors come in a range of shapes and sizes and some are more suitable to certain growing environments than others. Speak to our staff for guidance.


Ballasts are devices needed in HID grow light set-ups to regulate the voltage and current being supplied to the lamp. Without ballasts HID lamps would draw too much current from the mains and would instantly overheat and burn out.

Analogue ballasts

Traditional ballasts utilise magnetic resistance to provide the correct output to grow lamps. We stock analogue ballasts in 250W, 400W, 600W, and 1000W to accommodate for all HID lighting set-ups. 

Digital ballasts

Digital ballasts are a more modern alternative to the classic analogue ballast. They feature ‘soft start’ technology that helps prolong the life of your grow lamps and run significantly cooler than analogue ballasts. In terms of output and yield, there is virtually no difference whether you choose to use an analogue or digital ballast.

Some digital ballasts offer a ‘dimmable’ option, allowing you to run lamps of various wattages without the need to purchase ballasts to match each lamp. We stock a range of dimmable digital ballasts that are suitable for a specific range of grow lamp wattages.

All our digital ballasts are exceptional quality and from market leading suppliers.


There are a range of accessories available for grow lights that make installation easier and maintaining the correct light cycles much simpler. Using these accessories will relieve the stress of creating the optimum growing environment for your plants.


Timers are extremely handy for your growing environment and they can be used to control ventilation equipment, irrigation frequency, and light-cycles (when used alongside a controller). Without a timer you’ll have to manually control and monitor your growing environment which in most cases is inconvenient and if you lead a busy life, not practical.


Controllers are often necessary grow light accessories and are used to control the light-cycles of HID lights. Timers alone cannot handle the electrical load from HID grow lights so if you plan on using a timer for your light-cycles, you will need both a controller and a timer. We sell 2-way, 4-way, and 8-way controllers to allow for the control of multiple HID lights in a single growing environment.


Contactors work in much the same way as controllers and are used to control light cycles. However, we stock a range of contactors all of which which use top quality components and are overall much heavier-duty than regular controllers.

They are also more compact and have an in-built timer which frees up valuable plug sockets. One other great feature of the Maxibright contactors is the addition of switchable sockets, which means you can take total control of the lighting in your growing environment.

Light hanging equipment

If you buy a grow light then you’re going to need to use something to hang it with. You’re also going to want to use hanging equipment that makes it easy to change the height and distance that your grow light hangs above your plants. We stock light hanging equipment that can do just that. Easy rolls and jack chains are our standard light hanging equipment and our rope ratchet hangers are our heavy-duty hangers, able to hold up to 34kg of weight.