Should I Leave Grow Lights On For 24 Hours A Day?

December 25, 2021

Leaving Grow Lights On 24 Hours

Running your lights 24/7 gives your plants more light. If you find they are not getting enough, this is a simple solution to increasing the amount of light they get throughout the day.

But it is not the best solution.

If your plants need more light, the best way to remedy the situation is to get more light fixtures, or to swap your existing ones out for more powerful ones. Leaving your lights on continuously is not a good idea. Let’s look at the pros and cons to find out why.

Advantages Of 24/7 Lighting

Keeping your lights on 24/7 has one advantage: it gives your plants more light (ok, there is one other advantage: you won’t need any grow light timers). More light means faster growth.

If you leave your lights on around the clock during vegging, you will see faster growth, without a doubt. And you plants will start growing buds much sooner. But this benefit is outweighed by the disadvantages.

And leaving the lights on around the clock during flowering is not an option at all. Your medicinal plants won’t switch to flowering unless you reduce the lights to 12 hours a day.

If they are already flowering and you increase daylight to 24 hours, you’ll have a disaster on your hands. Your plants will revert back to the vegging stage and it will take forever to get them to re-enter the flowering stage. Never leave your lights on around the clock during flowering.

Disadvantages Of 24 Hour Daylight

Disadvantages Of 24 Hour Daylight
The disadvantages of leaving your grow lights on 24 hours outweigh the one advantage. The primary disadvantage is that your plants get no rest period.

  • No Time To Respire

Sure, you can leave the lights on all the time. Your plants will grow faster. But if you leave them on continuously for many days, your plants will get weaker and weaker. They won’t grow as strong and they will become more susceptible to disease.

  • Additional Costs

Running your lights 24/7 costs more money. You need to pay for the electricity to power the lights, and also for the electricity to power fans, air conditioners and any other equipment you might have running in your grow tent. You will also have to change bulbs more often.

  • Additional Stress On Equipment

Leaving the lights on all night long also means that they, and other equipment, are running constantly, without any breaks. This puts additional stress on them and results in a shorter lifespan.

  • Additional Heat

Running your lights constantly generates more heat. As mentioned, this means you will also need to run fans and other cooling equipment 24/7. It also means your plants do not get a cooler night time, which is something they naturally expect.

The Best Lighting Schedules For Medicinal Plants

We’ll start with flowering, because there is no flexibility to increase the daylight hours during this stage. Your lights need to be off for 12 hours per day (with the exception of autoflowers, of course). Keeping them on longer can result in your medicnal plants plants switching back to vegging and then you’ll have a hard time getting them to flower again.

During vegging, you have much more flexibility. It is perfectly possible to leave the lights on overnight, but as mentioned, it is best to give your plants at least some darkness.

The most common lighting schedule during vegging is 18 hours of light and 6 hours of darkness. This is the schedule we recommend. 20 hours on and 4 hours off works well, too.

Another interesting option is to use a 6/2 light schedule. What this means is you leave the lights on for six hours, then turn them off for two. You have 3 of these cycles per day. You still end up with 18 hours of daylight and 6 hours of darkness, but they do not all fall at once.

The folloewing are three best LED grow lights:

ECO Farm 780W/960W Foldable Full Cycle Dimmable LED Grow Light For Greenhouse

ECO Farm 780W/960W Foldable Full Cycle Dimmable LED Grow Light For Greenhouse

  • Low Power Consumption & High Energy Efficience: ECO Farm 780W/960W led grow light is composed of Philips customized 3030 full spectrum 418pcs, Optical macro chip 660nm16pcs, Epistar chip 740nm3030-2pcs, Epistar chip 395nm3030-2pcs,438pcs*6 2628pcs,
  • This plant light is specially developed for indoor plants/greenhouse/hydroponic plants. The best planting range for a single light is: 4' x 4' to 5' x 5' feet when working at 100% power. The grow lamp can bring1770 umol/㎡ of micromole (the test result was got at a height of 18 inches). In ideal conditions, you will get harvest four times one year.
  • Full Spectrum Grow Light: We produce a full spectrum light through Philips customized 3030 full spectrum 418pcs. The plant light is composed of 660nm/740nm/395nm LED chips.This grow light can be used in the seedling, flowering, and fruiting stages of your plants. Without any exaggeration that you can look upon it as a small sun.
  • Controllable Power Output: Indoor plants need different Luminous efficiency output in different growth cycles. Our grow lights are equipped with a dimmable knob switch. You can adjust the height of the grow light or adjust the power of the plant lamp to achieve the best energy output. This design helps us do easier shipment packing, and you can store it easier.
  • It has a 120° wide beam angle to provide excellent light distribution and cover a large area.
  • Combined with 3 or 4 even-sized parts, each part can be folded.
  • With manual dimming knob and controllable dual-network port R14, suitable for smart light controllers to connect up to 200 LED lights
  • Warranty: 5 Years

ECO Farm ECO-Net 680W/1000W Fordable Samsung 301B Chips LED Grow Light

ECO Farm ECO-Net 680W/1000W Fordable Samsung 301B Chips LED Grow Light

 ECO Farm ECO-Net provides highly efficient spectrum with a healthy red-to-blue ratio to drive photosynthesis Light energy between 500-599nm, which penetrates deeper into the plant canopy promoting photomorphogenic responses. High color rendering "white" light aids to rapidly identify potential threats to your crop and provides superior working conditions and safety for personnel. Ideal for both flowering and vegetative production.

  • 180°folding design, low shipping cost and easy installation.
  • Excellent heat dissipation structure design.
  • Al6061 alloy allows high-temperature resistance and corrosion resistance.
  • Full-spectrum meets every stage of plant growth.
  • High PPE up to2.73-2.75umol/J.

ECO Farm YT Series 720W/860W Foldable Full Spectrum LED Grow Light Strips With Samsung Chips

ECO Farm YT Series 720W/860W Foldable Full Spectrum LED Grow Light Strips With Samsung Chips

  • 【Foldable Design】180 degree foldable, easy to hang, strong structure. 
  • 【Easy Installation】Unbox, unfold, fixed and hang then it is done.
  • 【High Efficacy】High PPF Efficiency up to 2.70 µmol/J.

  • 【Daisy Chain Dimmable】Knob switch dimming+RJ14 signal cables daisy chain.

If you are also interested in other grow equipments, welcome to visit our website:

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WhatsApp: +1 206 581 5521

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