When Should I Run My Grow Lights?

When should I run my grow lights? To be effective, grow lights really need to be on for at least 8-10 hours a day. This can vary up to 16 hours, depending on the conditions. That's why LED grow lights are so popular – when they have to be left on all day, it's best to use an energy efficient type! Always position a grow light above the plant.

Should I run my grow lights at night or day?

Like the sun's cycle, it is unnecessary to run grow lights around the clock. A good general rule of thumb to remember, if your plant is flowering or a vegetable it needs 12 to 16 hours of light in a day and 8 hours of darkness to rest.

Are lights at night bad for plants?

Summary: Artificial night time light from sources such as street lamps affects the growth and flowering of plants and even the number of insects that depend on those plants for food, a study confirms.

Do grow lights need to be in the dark?

During light reaction, the plant absorbs light and turns it into energy. Because dark reactions do not require the absence of light, plants will remain healthy when exposed to light 24 hours a day. There are some plants, however, that will survive but not thrive without darkness.

Can I leave my grow light on overnight?

While leaving growing lights on for a single night is unlikely to have long-term effects on your plants, constantly leaving the lights on can stunt their growth, prevent flowering, cause wilting and burn damage, and may kill the plants.


Related faq for When Should I Run My Grow Lights?


How does darkness affect plant growth?

In a strict sense, plants do not grow faster in the dark; they grow slower. However, plants seem to grow faster in insufficient light due to rapid cell elongation. In conditions of total darkness, plant cells will generally expand upward, a process called geotropism.


Do seedlings need light at night?

Seedlings need 14-16 hours of light every single day, without fail. Don't leave them on for 24 hours a day though. Like us, they need to rest at night. If you give them less than 14 hours of light per day, then make sure to monitor them closely.


Do seedlings grow at night?

Yes! The absence of light actually stimulates plants to grow fastest at night. Plant phytochromes detect darkness, encouraging growth hormone production, causing the plant to elongate in search of light. The same process helps plants orientate their foliage to light and helps seedlings stretch in search of light.


Should grow lights be on all the time?

A: In general, you should not leave grow lights on 24/7. Plants need a light-dark cycle to develop properly. It's believed that they truly do “rest” during periods of darkness, and probably use this time to move nutrients into their extremities while taking a break from growing.


Is sunlight better than grow lights?

Red light helps plants produce flowers and fruit, while blue light helps them grow leaves. Sunlight provides the full spectrum. But sunlight is a lot more powerful than grow lights. A plant gets about the same amount of energy from 13 hours under a grow light as it does from six hours under the sun.


What makes a grow light a grow light?

Most grow lights provide full-spectrum light. Most of the light plants use is from the blue ("cool") and red ("warm") ends of the spectrum; they use little yellow and green light. Blue light stimulates vegetative growth (foliage and roots) while red light stimulates plants to produce flowers and fruit.


What is best light cycle for veg?

Most growers that grow their plants indoors begins from the point of 12 hours of darkness immediately the plants have reached the desired size and shape during their vegetative stage. Usually, most growers prefer an indoor vegetative period of 4-8 weeks under a 24/0 or 18/6 light period.


Do Autoflowers grow overnight?

Technically speaking, autoflowers don't need darkness because the Ruderalis is accustomed to 24 hours of daylight at times in the wild, depending on the season. They can be grown in any light cycle as long as the conditions are favorable in terms of temperature.


When should I switch my Autoflower lights?

24/0 then switching to 12/12 – The best option if you want to use the 12 hour days is to start your plants under 24/0 or 18/6 while they are in their vegetative growth stage and then switch that light cycle to 12/12 when the first pre-flowers appear.


Are Autoflowers female?

Autoflowering, feminized cannabis seeds will flower without a change in the life cycle and will result in nearly 100% female plants. Like any autoflowering seed strain, you should expect a slightly smaller harvest than a crop of the same strain grown from “regular” seeds.


Do all plants need darkness to grow?

Plants do need that period of darkness for their metabolism to work properly. They are not designed to create food non-stop, and it will do them harm in the long term to put them in this sort of situation. So, yes, plants need their darkness just as much as they need their light.


Do seeds Grow Faster in light or dark?

Most seeds germinate best under dark conditions and might even be inhibited by light (e.g., Phacelia and Allium spp.). However, some species (e.g., Begonia, Primula, Coleus) need light to germinate (Miles and Brown 2007). Don't confuse seed light requirements with what seedlings need. All seedlings require sunlight.


Why do seeds grow better in the dark?

(Explanation: seeds store a lot of chemical energy in the form of fats and proteins that can be used to grow in the dark. Once this stored chemical energy is exhausted, the plant requires light to grow taller.)


Are my grow lights too close?

During the flowering stage LED Grow lights should be located between 16-36 inches from the plant canopy. However, if the grow lights are too close above plants, they can cause wider, more sprawling growth or can even damage the plant.


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