Lights For Growing Weed Indoors

 Growing weed indoors for the first time

can be tricky …..

and you’ll waste a lot of time and money without the right guidance so spend some time reading the information on this website and on our sister site; How To Grow Weed Indoors

We have a lot of experience locating seeds, using the correct soil and nutrients, cloning and choosing the right lights for the grow room.

This website will deal mainly with the different aspects of lighting but we will also have information that will help you choose the soil and nutrients as well as showing you how to set everything up to have a successful grow.

Don’t worry, we don’t like techno mumbo jumbo either and believe us, there is plenty of lighting and growing mumbo jumbo (bluish-reddish-this shows how techy we get!) out there so we’ll break it down and make it easy to understand.

Why bother?

If you want a decent amount of great reefer for the risk, time, and money you spend growing indoors, you must have decent lights or you’ll be disappointed.


 T5 Grow Lights

T5 lights are fairly inexpensive and cool to the touch and can be used but are not the first choice for lighting. We discuss the T5 and state our opinion here.

We think the light of choice in 2015/2016 are LED lights.

One of the benefits of T5 was the low heat they generate compared to HID lighting. LED solves the heat issue plus you get the power of HID.





CFL: Compact Fluorescent Lamp

Inexpensive, no ballast needed, cool running, can be used but you won’t get maximum yield as the plants/buds will be smaller.

From your local store, CFL’s are sold with an output of 2700k lumen, good for flower growth and they are reasonable in price.

CFL’s with a lumen range of 6400k lumen, good for vegetative growth have to be purchased at a specialty store at a much greater price or check online at Amazon or eBay.

CFL Bulb

100 Watt CFL Bulb

Great for rookies; learn about soil, additives, bugs, disease and lighting the first time around before investing in more expensive lights for the next grow.

We use the bulbs in clamp light holders (pictured) for starting clones and/or seedlings when they’re very young. We also use them to focus light on a certain plant section that may need more light.


Clamp Light Holder

Clamp Light Holder

MH: Metal Halide Bulbs

Is a HID (high intensity discharge) bulb. They are cheaper than HPS and run just about as hot.

Apollo 400 Watt MH Bulb

400 Watt MH Bulb

A ballast is needed for MH bulbs.

Best to use during the vegging cycle.

If there is enough room and you have the lights, run the MH and the HPS bulbs at the same time during flowering too.

Many growers use both through out the grow with great results and we have too.


HPS: High Pressure Sodium

Is a HD bulb and is most expensive of the 3.

Apollo 400 watt HPS bulb

400 Watt HPS Bulb

A ballast is needed for HPS bulbs.

Using a wide spectrum HPS bulb (a little more expensive) gives more of a MH type (bluish) spectrum along with it’s reddish type spectrum, kind of like the best of both worlds.

We use the wide spectrum HPS along with MH bulbs and have great results.

The heat generated by HD bulbs can be severe and could prevent you from growing inside during the summer.




Never touch the bulbs when they’re hot and never touch the bulbs with your bare fingers. Use a soft cloth or even better wear a pair of cotton work gloves when handling the bulbs.

Never water or spray/mist your plants when the bulbs are on or hot. Even a mist can cause them to explode.

Some ballast have a built in fan that aids in cooling. They do make noise but nothing unusual or annoying and we recommend using ballast with fans.

Lumatek Ballast

Lumatek 400 Watt Ballast

Make sure the ballast is in a location with room for ventilation and is not touching anything except a flame retardant surface like a wire rack or a flat stone. We have used both and the wire racks work great as they allow for full ventilation and cooling.


What Light To Use When


Metal Halide Lights, also know as MH, are the best lights to use during the vegging cycle of your grow (the first 30-60 days).

Without getting technical, they provide the light that falls into the blueish spectrum which promotes the type of beginning growth you want for the awesome buds you’ll have coming later.

If you buy a dual ballast (handles both MH and HPS), it’s easy to use the MH bulb for the veg cycle than switch the bulb to a HPS (High Pressure Sodium) when moving to the flowering stage.

If you have the room and the budget, using MH and HPS at the same time during the flowering stage works even better but just HPS is fine too.

It’s important to read and follow the suggestions on handling these bulbs as they can be fragile and dangerous.


NOTE about the Apollo Bulbs shown within this post

We tried the Apollo 400 watt dual ballast (MH and HPS) a couple of years ago mainly because it was the cheapest set up around. So cheap in fact it took us 6 months before buying one, I mean how can a set up more than 50% cheaper than the Lumateks we were using be any good?

The ballast is a little noisy (not a deal breaker) because it has it’s own fan but it runs cool enough you can leave your finger on it and not get hurt (do that with a Lumatek ballast and you’ll get burned they’re so hot).

The 400 watt worked well enough to try their 600 watt setup. It is as reliable and deliver the same performance.

If money is tight using Apollo makes a lot of sense; they work well and you can’t beat the price but Apollo will generate lower lumen readings than the better ballasts but still are high enough for a great yield.

We haven’t any warranty issues with Apollo products and people who have had a problem have commented that they were taken care of satisfactorily. Plus they’re sold on Amazon. No matter what, Amazon makes sure the customer is satisfied so you really can’t lose.


In a Nut Shell

At the end of this page, we have a link to the best forum post about lighting you will ever read. If it’s technical information you want, this link will be just what you are looking for.

High Pressure Sodium Lights, (HPS) is for the flowering cycle. They use a ballast and provide light from the reddish(for flowering) type spectrum .

We promised low tech here and you can’t get any lower tech than “reddish”.

Super HPS bulbs have a wider spectrum and include bluish light(for veg cycle) which promotes a more veggie growth and can be used for both cycles but they do cost a little more.

This combination does work well and we also have used a straight MH light during flowering as well.

The HPS bulb pictured is from Apollo purchased on Amazon. They are a fraction of the price of other bulbs and have worked fine for us.

We recommend giving the Apollo a try.

For seedlings or clones, at one time we started them under a 100 watt, 6400k CFL bulbs and a clamp light running 24/7 for the first couple of weeks.


Now we have switched to using LED for everything, including clones and seedlings but follow along if you haven’t made the switch to LED yet.

It really depends on the strain/plant, but when your plants have a few fan leaves and are growing well and looking strong it will be time to switch over to the more powerful lights.

We’ll go another couple of weeks 24/7 with the more powerful bulbs than switch to 18 hours on and 6 hours off for another few weeks before switching over to GLR.

This will keep the plants in the vegetative cycle.

We have uses a good quality mechanical timers to turn the lights on and off but prefer the digital timers as they are more accurate but they do wear out at from 6 months to a year. Mechanical timers have good results but the digital one is a little more accurate.

Depending on your strain and time frame, you’ll want to veg between approximately 30 days and 60 days.

In our opinion, the quality of the weed doesn’t change vegging for shorter periods of time (30 days). What does change will be the size and yield so consider that when deciding on long you want the veg cycle to run.

Generally speaking, the plants will almost double in size after flowering so keep that in mind. Some growers start flowering within the first few weeks of the veg cycle. Of course they’ll get results sooner but the yield will suffer.

As long as the plants look strong and are growing well, you can start the flowering process in as little as 30 days by changing your lighting schedule to 12 hours on and 12 hours off.

You’ll notice white hairs within 14 days (those will be the females). Using the GLR, the flowers will show themselves much sooner.
The males show themselves much quicker than the females, sometimes in as little as 2 days! You can tell the male when you see clusters of tiny little balls growing.

Get rid of the males and you’re on your way to some great buds.

You can flower anywhere from about 30 to 60 days or more depending. If you go too long, the females will morph and turn the flowers into seed pods.

The pot will be just about as good, but the new seed pods really have a terrible taste (you’ll never get use to it) so don’t run the flower cycle too long and check often for seed growth in the latter stages.

We haven’t tracked the electrical expense very well but roughly speaking, running about 2300 watts of lights cost about about $180.00 per month.

These are broken down into one, 600 watt and two 400 watt HD lights and one, 300 watt and one, 600 watt LED.

Since we have switched to all LED, our energy cost has been cut in HALF!

The lighting method for the veg cycle called the Gas Lamp Routine (GLR)  can reduce the cost of electricity quite a bit during the vegetative cycle.

When using GLR, run the lights 12 hours on, 5.5 hours off, 1 hour on, 5.5 hours off.

There are many explanations about why this works but in keeping with our low tech promise; by using the GLR you are building up the flowering hormone so when you flip to flowering, (12 hours on – 12 hours off) you will have more explosive budding in a faster amount of time while saving on your electricity cost.

We use GLR and recommend it.

When flowering, start with 12 on and 12 off.

After 2 full weeks, switch to 10 on and 14 off and use this schedule until the last few weeks. Switch to 9 on and 15 off for the last 2 weeks of your grow leaving your lights off for the last 2 days.

Go here if you want to read the techno mumbo about lighting but it boils down to what we are including in the sections on this page.




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