Indoor Grow Lights

Providing sufficient light to your plants is essential. So where do you start? LED, CFL, or HID? Warm lights? Cool lights? 250W? 400W? 600W? 1000W? double ended? The list goes on. For the beginner it can be a minefield so here’s what you need to know about indoor grow lights.

Warm vs Cool:

Grow lights are labelled with numbers such as 2700K (K stands for Kelvin) or 4000K for example.

These relate to the warmth or coolness of the light. Don’t misunderstand me here they all run warm/hot, but in the lighting terms the higher the number or Kelvin the cooler the light.

For Veg  (The vegetative stage) you would need around 6500K, which would be classed as a “cool” light.

For Flowering and Fruits you would need around 3000K, which would be classed as a “warm” light.

If you are growing seedlings, leafy green vegetables, or root crops, you only need higher Kelvin rated bulbs. If you want to grow flowers, or any fruiting plant such as Chillies or Tomatoes however you will also require low Kelvin bulbs.

The 3 main types of Grow Lights.

The three main types of growing lights in the industry currently are :

CFL LIGHTS

Compact Fluorescent Bulbs (CFL’s) 

CFL grow lights are reliable and economical for raising seeds, cuttings and for vegetative growth.

CFL’s produce little heat, consume little power, and require no ballast, making them a good choice for small gardens or tight budgets.

CFL’s can be used throughout your plant’s entire life by alternating between the blue and red spectrum. Be warned however that using CFL’s throughout Flowering will result in lower yields than if you use HID lights.

T’5s, Fluorescent tube lights. 

T5 Grow Lights are primarily used for propagation and Veg when blue light is needed most. T5s are not recommended for the flowering/ fruiting stage, as they will yield considerably less than a HPS grow lamp.

T5’s are available in 2, 3, 4, and 5ft lengths. They are 40% smaller than T8 fixtures but are capable of producing just as much and sometimes more light in a smaller area. 

They are lower maintenance than other fluorescent bulbs and provide more light (lumen) than other fluorescent bulbs, saving you money.

HID Grow Lights.

HID’s (High Intensity Discharge) lights are extremely powerful and as a result are expensive to purchase. The powerful nature of HID lights means that they do have a tendency to consume electricity inefficiently and give off a lot of heat. As a result HID lights require special light fixtures and ballasts.

Despite these points, HID lights are very effective and remain one of the most widely used lighting options within the hobbyist indoor gardening industry, as they produce great yields! HID’s are best for large plants because the intensity of light penetrates farther into the foliage than other bulbs.

Metal Halide (MH) grow lights.

Metal Halide Grow Light Bulbs are best used during early Veg, as they produce light in the blue spectrum (cool light).

MH lights can be used throughout the entire grow cycle but it’s recommended to use MH for Veg and then move to the HPS for Flower. 

If however you only have the option of buying one bulb, I would recommend that you choose the HPS bulb as it will perform better over all through an entire grow cycle.

High Pressure Sodium (HPS) grow lights.

HPS lights emit light in the orange to red (warm) spectrum and are best for the Flower stage. Their lack of light in the blue (cool) end of the spectrum makes them okay for Veg but not ideal.

HPS lights use a lot of energy and create a lot of heat, which needs to be managed properly with a suitable ventilation system.

HPS Dual Spectrum.

Dual Spectrum lights deliver enough blue light to be used throughout Veg and Flower, saving on the need for 2 separate bulbs. Highly recommended as good all round growing and flowering lamps they come in 600w and 1000w capabilities.

As you are using the bulbs for both phases of your Grow cycle however, the life span of your bulb will be reduced pro-rota to how much they are used.

All bulbs mentioned in this section need to be used in conjunction with the appropriate ballast. They all come in either 250W, 400W, 600W or 1000W and thus should be used with the correct corresponding ballast.

The 2 main different types of ballast are magnetic and digital. They both do the job required but a “digital” ballast is generally seen as being more energy efficient.

As for the best shade to use with your bulb and ballast, this will all depend on what “spread” of light you are after. The most commonly used shade by far is a “Dutch barn”, hammer-tone shade. This is a versatile, value for money choice and therefore is the most commonly used.   

LED Grow Lights.

By far the most expensive and newest range of Grow lights.

LED’s are efficient and economic to run. The cool running of an LED system eliminates the risk of heat damage, and fire hazards. LED’s typically last for 50,000 hours+, whereas HID bulbs generally last 10,000-18,000 hours. 

Dual spectrum LED systems can be used throughout your grow cycle with no switching of bulbs. You can even install a system that’s tailored specifically to the type of crop you grow.

LED’s, fit into smaller, tighter areas, meaning you can create a more compact grow room, without the risk of heat burn.

LED lights normally come with a built in ballast of sorts. So you would not need to use an additional ballast as you would with a HID style bulb.

How to Install Grow Lights.

Installation requirements can vary depending on the size of your indoor garden and the type of bulb but here are a few basic rules.

Your bulb and shade need to be positioned within your growing environment however it is advised that you keep your ballast outside of your growing environment.

This is important, as keeping the ballast within your growing environment will increase the over all heat output and raise the temperature too high which could be to the detriment of your plants health and development. Not to mention the fact that it poses a serious fire risk!

Light Height.
Support the lights at the proper height and have a way to raise them as the plants grow. Use a rope ratchet pulley system or hang the fixtures with metal chain.

By using rope ratchets to hang your lighting system it is very easy to adjust them to the correct height. The optimal distance that your lights should be positioned above your plants canopy will depend on what you are growing and what bulb/ light system and wattage you are using, so always double check before you start out.

Here is a rough guide however.

Fluorescent: 3-12 inches away from your plants canopy.

LED: 12 -24 inches away from your plants canopy.

HID: 24-60 inches away from your plants canopy.

Hopefully you will now have a basic understanding on the differing lighting systems that are commonly used in indoor growing environments and what it is that you are looking for to get your garden started.

By Rich Hamilton

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