What Kind Of Fluorescent Lights To Grow Plants (Including Weed)?

The short answer is: any type of fluorescent light will help any type of plant grow, whether it is cannabis or lettuce or orchids.

But it’s not quite so simple.

While you can use any type of tube or bulb and see results, you want to provide the kind of light your plants want most.

That’s how you get the best results.

So what type of light do your plants need?

That depends on a few things.

1. Are they plants that flower (like marijuana) or ones that don’t?
2. If they flower, they need different type of light depending on their current stage of growth, so you’ll need to take that into account
3. Are they already getting some natural light or will they be growing under artificial light only?

 

Fluorescent Growing Lights: CFL or T5 Tubes?

Before we get into the specifics on the types of bulbs or tubes, let’s first decide whether we want to go with fluorescent tube lighting or with compact fluorescent bulbs.

The answer is simple.

If you’ve got a very small garden, CFL bulbs (pictured at the beginning of the article) make the most sense.

If your garden is large enough to warrant a larger T5 or T8 tube fixture, go with that. And perhaps supplement the light with a few CFLs, especially for plants with high light requirements, like weed.

As for which bulbs to get, it doesn’t matter with CFL bulbs. You can just get any standard bulb from your local Home Depot or Walmart or order online (if you’re unsure about the correct color temperature, I cover that below).

Amazon has a bunch of CFL bulbs, too.

There is no need to get a specialized (and overpriced) grow bulb. They’re basically the same thing. It’s just a way to get more of your money.

For T5 fixtures, I recommend the Agrobrite line from Hydrofarm (pictured above). We reviewed them here, but the quick summary is that they cost about the same as most no-name fixtures from China, but work far, far better.

You can use regular fluorescent bulbs from any local store, but for larger fixtures like this, it make more sense to buy from a company specializing in horticultural lighting. And Hydrofarm is the biggest name there is.

Now, let’s take the first question from above and tackle plants that flower and those that don’t separately.

The second and third questions will be answered naturally as we go along.

 

What Fluorescent Bulbs For Growing Flowering Plants (Marijuana, Tomatoes, Etc)?

Flowering plants, like cannabis, need more and different light than non-flowering plants. But only during the latter stages of growth.

In the beginning, flowering plants need the same light as non-flowering plants. When they are seedlings and when they are growing (vegging), they need light that contains more blue than at other times. This is also often referred to as ‘cold light’. It is the kind of light our sun gives off naturally during daylight hours.

When the plants have grown enough to begin fruiting or flowering, they need more light than before and they prefer a warmer light, i.e. light that contains more red.

So if you are growing tomatoes indoors with artificial light (or cannabis, of course), how can you give them the light they need with fluorescent bulbs?

By using bulbs with varying color temperatures.

During the seeding and vegging stages, we want to use bulbs labeled ‘cool white’ or ‘daylight’. They will have a color temperature (usually indicated on the package) in the range of 6000K to 6500K, like these.

During flowering, ‘warm white’ bulbs are ideal, with a color temperature of 2700K to 3500K. These bulbs are good.

It might seem like a hassle to change bulbs when it is time to go from vegging to flowering, but it’s really only a big deal if you have a very large garden with a lot of lights.

And if that is the case, you should not be using fluorescent lighting anyway, as the disadvantages outweigh the advantages once a grow gets too large. Our article comparing T5 grow lights vs LED has more on this, too.

However, if you just don’t want to bother with having to change the bulbs, you can get lights with a color temperature in the middle, somewhere around 5000K.

These bulbs will work fine for all stages of growth. In reality, any bulb will work for any stage, but using bulbs that provide the right kind of light yields much better results.

In most cases, you will want to supplement the light you use during vegging with some additional bulbs. Personally, I just hang a few CFL bulbs (warm light) here and there to add some more output and really stimulate flower and bud production. If you are unsure how many CFLs you need, this article will help.

 

What Kind of Fluorescent Bulbs For Plants That Don’t Flower?

If you are growing plants that don’t flower, like cacti, herbs, lettuce, etc. then you do not need to worry about providing warmer light during flowering.

You just need to get some ‘cool white’ or ‘daylight’ bulbs and use them all the time. No need to switch lights. This article reviews the best T5 bulbs for vegging.

If you need some more ideas for non-flowering plants, read this article on the best vegetables to grow indoors under lights. It lists a few of them.

If you are growing flowering plants, even succulents, a LED light might be a better choice. You pay more upfront, but you save more int he long run. We have an article on how to use LED grow lights for succulents.

 

Best Fluorescent Grow Lights

Let’s quickly summarize which fluorescent lamps are best, whether you are interested in getting CFLs or T5 lights.

 

CFL

As mentioned above, when it comes to compact fluorescent lamps, I would not worry about getting a dedicated grow bulb. They cost a lot more, but are basically the same as a regular CFL bulb.

As for which brands are best, follow the links provided above to see my recommended bulbs for each color temperature. I like those lamps, because they offer the best value for money.

Amazon will also show you other options, so you can easily see some alternatives and do a quick comparison for yourself, if you don’t like my recommendations.

 

T5

When it comes to T5 lights, I always recommend the AgroBrite fixtures from Hydrofarm. Check out my AgroBrite review to see why I prefer these lights.

If they don’t have a fixture in the size you need, or if you only need bulbs, this post reviews and compares the top T5 tubes on the market.

Update: while I still love fluorescent light for growing cannabis and other plants, these days I tend to recommend T5 LED lights instead. They are basically exactly the same as a T5 fluorescent light, but they run cooler and use less power. They also last much longer.

They do cost more, but end up paying for themselves within a year, since they cost less to run and you don’t have to replace them for many years.

 

What Kind Of Fluorescent Lights To Grow Plants: Final Thoughts

The most important information to take from this article is that you want cooler white light for growing (5000K to 6500K) and warmer white light for flowering (2700K to 3500K). If you want to use a single bulb for everything, 5000K works well.

That said, we recommend warmer light over cooler. Flowering is more important, so we recommend putting your eggs in that basket and going with a 3500K or 3000K bulb, even if you are using it for all stages. However, since these bulbs do not cost much, you might as well get separate vegging bulbs.