Lighting Guide

Lighting Guide

In this guide, we will walk through lighting options, best-practices and schedules. There are several lighting options available to farmers these days and the right choice depends on your situation. At the end of the article, we break it down by type to help you find the perfect light.

Lighting Options

Sunlight

Natural sunlight is a great option if available - it's free and renewable. Sunlight through a window results in low yields, so you will need to live in an area where its safe to have the plant outside during the day. You can augment sunlight with artificial light sources.

Pros: Free and natural and your plants are naturally optimized to take advantage.
Cons: Not very stealthy and you can't control the weather or the seasons.

Fluorescent

Compact Fluorescent Lights (CFL) and fluorescent tube lights can be great options for your plants. The upside is that they're cheap, burn relatively cool and are easily available - you most likely have some in your home right now. The downside is that since they don't transfer as much power to the plants as LEDs, they can burn hotter.

You will need around 50 watts per square foot (0.3 Meters) during the vegetative phase and 75 watts per square foot (0.3 meters) in the flowering phase.

Pros: Cheap and readily available to get started
Cons: Burn hot compared to LED and not as efficient as other methods

LEDs

Over the past years, LEDs have overtaken almost all other lighting types for home grows. They are relatively inexpensive to purchase and operate and burn very cool compared to traditional grow lights. In almost all cases, we recommend LED lighting to other sources.

LEDs wattage vs lighting capacity is a confusing topic. Manufacturers attach a wattage number, but that number refers to the full capacity if every LED chip burned at maximum capacity (e.g. A light with 100 chips and each is at 10 watts max rating has advertised wattage of 10x100=1000 watts). Since LED chips don't burn at their max capacity, the actual wattage pull at the wall is generally about half the advertised wattage.

The most important number for LED grow lights is the photosynthetic active radiation rating, or PAR rating. PAR isn't a measure of brightness (like lumens, which measures human visible light) but is a measure of the light ranges that are specifically beneficial to plants. Quality light manufacturers publish PAR ratings at set distances to establish coverage area per light.

Pros: Most efficient and still fairly inexpensive to get started
Cons: Less available than CFL

Cannabis buds under an LED light.

HPS

High-Pressure Sodium lights are extremely effective lights and have been successfully used to grow amazing buds for decades. They do burn hotter than LEDs, which can cause temperature problems in tents and other confined spaces.

Often, farmers use multiple sources. You might keep seedlings on a window sill during the day and move under fluorescents in the evening.

Pros: Fairly efficient and productive
Cons: Expensive, burns hot and not readily available locally

Lighting Schedule

There are a couple of things to consider on lighting schedules. To keep photoperiod strains from entering flowering, vegging plants need more than 12 hours a day. Light cycles are generally denoted as light/dark hours. Standard options are 18/6 (18 hours of light followed by 6 hours of dark), 20/4 (20 hours of light followed by 4 hours of night) and even 24 hours of light without any darkness.

During flowering, photo-period strains require over 12 hours of uninterrupted darkness each day. Even a single flashlight sweeping over can be enough to stop some strains from flowering, so light control during flowering is essential. For auto-flowering strains, this isn't an issue since their flowering is controlled by an internal timer that starts ticking at germination.

For outdoor growing, the seasons control the light schedule. For indoor growing, tents, closets and grow boxes have good light control and most farmers use inexpensive electronic timers to turn lights on and off on a schedule. Keeping a tight schedule with automatic timers are good for the plant and easy for the grower.

Lighting Controller

The best way to keep your plants on a good schedule is to pick up a timer. These are inexpensive and readily available online or at local hardware or department store. The important note is to make sure that you get a unit that can handle the wattage your light setup pulls. You also need to get a grounded unit (3 prongs in the US) - many of the cheaper analog units are made for household lamps and the like, so they only have two hole plugs. It's worth spending a few extra bucks for safety.

We use this Vivosun 7 day programmable timer with two outlets. Click here to read the stats on Amazon.

LED Light Types

Flat Panel LED Lights

These small full spectrum lights don't put out a lot of power (only drawing 30W at the wall), so they don't need built-in fans, which makes them quiet and efficient. For germination. For germination and young seedlings, hang them 12 to 18 inches high. For vegging and flowering plants, use them as side panels to add a little boost.

cover about 1 square foot (~ 0.09 square meters).
Good For: These are great for germinationn, seedlings or as a secondary source.
Not Good For: These lights are not strong enough to support vegetating or flowering plants by themselves.

We use this LED panel light for germination, starting clones and seedlings and highly recommend it. Click here to learn more.

UFO Style LEDs

These small, disk-shaped lights usually have 50 chips at 3 watts each for an advertised rating of 150 watts. In reality, they pull ~50 watts at the outlet and have a built-in fan. For germination, they cover around 2'x2' (60cm x 60cm) when hanging 18 to 24" (45 to 60cm) high and for veg cover about 1 square foot (~ 0.09 square meters) at 12" (30 cm). They aren't enough for a flowering plant by themselves but make a great way to fill in dark spaces in your tent.

Good for: Seedlings and early vegetative or as a secondary light source.
Not Good for: Solo lights for flowering plants

We use this UFO LED for seedlings, young vegetating plants and to fill in dark spots in the tent.

LED Reflector Lights

These are regular LED grow lights but have a reflective back to improve efficiency. Ranging from 150-watt power draw to over 2k, coverage varies.

Good for: Vegetative and flowering stages
Not Good for: These lights can be too strong for seedlings.

This 300W is perfect for seedlings and vegging and works well for a small plant in flower. We wrote a full review on it here.

This 800W LED is perfect for vegging and flowering. Click here to see the full stats.

LED COB Lights

Chip-On-Board are just like the regular LED lights, but they have a simplified design with multiple diodes to improve efficiency and durability.

Good for: Vegetative and flowering stages
Not Good for: These lights can be too strong for seedlings.

We use these chip-on-board lights in our tents every day and highly recommend them:

Next Up: Learn about containers and soil.

Learn about the different container and soil options available, and all about transplanting marijuana plants as well.

Learn about containers and transplanting
Learn about soil and growing mediums

About Author

Kinder.farm

We believe that everyone can grow beautiful cannabis gardens

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