What is the best light spectrum for clones? In short, there is no clear definitive answer until somebody proves otherwise. However, for those growers looking to maximize their clone grow potential, I will point you to a spectrum and light that I feel confident about.

It seems like every indoor clone grower uses a different type of light that has its own unique light spectrum. But if every grower uses a different type of light, does the type light spectrum even make that big of a difference? Maybe.

Since we know clones can grow from virtually any light source, the easy answer is for growers to continue using whatever light source they have. It works, but is it optimal? Probably not.

How to Improve your Clone Grow

If you are grower looking to maximize your clone grow potential, this article is for you. I also urge you to share in the comment section if you have experience or expertise in this area.

So what is an optimal clone grow? For me, an optimal clone grow is a group of cuttings that roots as fast as possible and resumes the vegetative growth phase without sacrificing time and money. For example, an optimal clone grow might only take 6 to 9 days to root and resume vegetative growth a day or two later.

But what about all the other factors that go into cloning, don’t they play a roll as well? Definitely. Cloning is a process and there are plenty of things you must consider like humidity, moisture levels, medium and so on. This blog is not a 101 course on cloning. Instead, I want to focus the next section on lights and spectrum.

Best Light Color for Clones

In my opinion, the best light spectrum for clones is produced by cool white fluorescents. Another option is to combine cool white fluorescents and warm white fluorescents.

Can I use LED, HID or MH lights? Yes, but they aren’t as effective as fluorescents. A lot of times, these lights are simply too powerful for clones. LED’s, HID and MH also cost a lot more money to run. For me, cool white fluorescents are the best lights for young clones. Fluorescent lights are affordable and work great! If cool white fluorescents are not an option for you, another great option are household CFL’s. Some clone growers use spiraled CFL’s and have great success.

Cloning Tips:

• Give your clones at least 18 hours of light.
• Always take clones from healthy mothers that are vegging and growing strong. Avoid cloning sick and bug infested plants.
• Make sure to use clean and sterile equipment when cutting.
• Clones usually root faster with low light levels.
• Blue light helps with rooting.
• Clones need a minimum of 400 ft. candles or about 4300 lux. Use an inexpensive light meter to determine your light output.
• Too much light can slow your clone time drastically. Try to avoid using powerful lights. If all you have is a HID, then I recommend that you place your clones several feet from your light source so that they receive less intense light. If they are still getting too much light, you could also use a shade cloth to help.
• Red lights helps with plant growth and flowering.
• Clones will progressively require more light as they get stronger and hardened.
• Metal Halide light sources also work well for cloning. If you have a 400 watt MH, I recommend keeping your clones about 5 to 6 feet away.
• It is critical that your clones develop strong root systems before exposure to bright light.

Conclusion

Lastly, if you have any questions or comments please post them in the comment section. If you are interested in learning even more about growing cannabis, please check out my blog. Here are a few of my most recent posts: 

• The Cannabis Growing Season – Southern California
• Is a Grow Tent Necessary
• Trichomes When to Harvest
• Cannabis Water Filter
• Organic Fertilizers for Cannabis
• Cannabis Pot Size Guide