How Long To Leave Plant Light On. Read This First

If you want to know how long to leave plant light on, you must classify your plants into seedlings and mature plants. It’s not enough to master when to use a growing light, but you also have to perfect your plant’s light exposure duration. Remember that the greenhouse will only be the perfect plant environment if you can provide the factors that they need properly, including light. 

According to the University of Maryland Extension, lights are essential for producing sturdy plants. However, you don’t want to leave the plant light over the ideal recommendations. This article will discuss the limits and best duration for leaving the plant light both for young and mature plants. 


How Long To Leave Plant Light On. Read This First

How Long To Leave Plant Light On: Everything You Need To Know



As mentioned earlier, you need to classify your plants to know the duration of light exposure suitable for them. You can leave the plant light on for 16 to 18 hours every day to encourage growth for seedlings. This is longer than the recommendation for mature plants because younger plants require exposure more for their development. 

You can use full-spectrum lights at 6 inches above the seedlings in the greenhouse. The light intensity is also as necessary, so the best fixture to use are four tubes. Check your set-up afterward to ensure that plants receive the light equally and at the maximum intensity using reflectors to reach the plants’ top and sides. 


Mature plants

Compared to leaving the light on for a maximum of 18 hours, more mature plants can thrive best at a duration of 12 to 14 hours. However, do note that different plants will vary on the maximum requirement. Therefore, some plants can grow sufficiently with six hours of exposure, while some only require four hours of intense light every day.

With the former, you can place the lights a foot away, and those with low light needs can have a distance of three feet from the fixtures. You must also keep in mind the intensity required for your plants and if they also receive sunlight. Gardeners often leave the plant light on for six hours at night if the plants do not receive their optimal requirements during the day. 


How Much Light Do Plants Need In The Greenhouse?

Now that you learn how long to leave plant light on, the next step is to ensure that you are not overexposing or underexposing your plants to light. An easy way to do this is to create a routine using an alarm and timer to know when to turn on and shut off your lights in the greenhouse. Different systems won’t need manual intervention for your convenience. 

The system will automatically switch the lights on and off for you, but you can also use a simple alarm to notify yourself of the routine. More so, always monitor your plants for any signs of overexposure or underexposure to the lights. For example, those that receive light over the limit can experience wilting and yellowing of the leaves, while those that require more light can die because of the failure to do photosynthesis


Light Intensity In The Greenhouse

You must also check the light intensity in the greenhouse to ensure that your plants meet their requirements. You can measure light intensity in foot candles, and to give you an idea, seedlings require 1,000-foot-candles for growth. However, the fixtures’ distance to the plants also plays a role, and the specific requirements of your species will vary. 


Types Of Greenhouse Lighting Fixtures


T5 Fixtures

If you’re considering using fluorescent lights, the best fixtures to use are T5 fixtures. They are excellent for growing in the greenhouse because of their long lifespan while also using less energy and causing a low impact on the environment. T5 fixtures are ideal for starting seeds until the plants grow entirely. 


High-pressure sodium fixtures

Another popular fixture that you can have in the greenhouse are high-pressure sodium types. Compared to the first one that is best for starting plants from seeds, these fixtures are useful if you want to encourage budding and flowering. They are an excellent alternative for the traditional incandescent bulbs for use later in plants’ growth cycle.


LED fixtures

Lastly, the most modern and long-lasting fixtures are LED bulbs. They have a long lifespan and minimal heat output making them more energy-efficient in the long run. You can also choose from different types if you want fixed or programmable fixtures. 



We all know that plants require light for their growth and development, and the invention of the greenhouse allows us to mimic the optimal environment for our plants. Therefore, you must know how long to leave plant light on to ensure that your plants grow healthily. In general, younger plants should receive around 18 hours of exposure while their more mature counterparts can do well with only 14 hours. 

However, the emphasis is necessary on checking the light intensity and distance as well. More so, different plants have different requirements, so that these lengths will vary. The main takeaway here is that younger plants should have their light on for longer compared to mature plants.


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How To Prevent Root Rot In Hydroponics: 3 Useful Tips

If you’re a newbie gardener who’s looking to find ways to hone your skills, you’d want to learn how to prevent root rot in hydroponics even before this problem affects your plants.

Hydroponics can be advantageous to crops in more ways than one. However, it also comes with risks of diseases, such as root rot, which can be destructive or even lethal to your plants.

Unfortunately, there are no effective methods to recover the wilted parts that were affected by the root rot once it hits your plants. The only thing you can do if you do not want this catastrophe to befall your crops is to prevent it before it happens. Read on to learn more about this subject.


What is Root Rot?

Root rot is a disease that attacks the plant roots and causes them to suffer decay. This usually happens when a lack of oxygen supply occurs in the substrate.

To give you an idea, think about plant roots that are submerged in water that only has a little oxygen in it. Over time, the plant suffocates and dies.

Aside from rot and decay, this disease also leads to the proliferation of fungi that are naturally present in the soil. These include Rhizoctonia, Alternaria, Pythium, Botrytis, Fusarium, or Phytophthora. As soon as fungi colonies start to grow, they tend to target the weakened roots and infect your precious plant babies.

Once the plant becomes infected, they won’t be able to take in what they need to grow – water, oxygen, and other nutrients. When this happens, it won’t be long before the plant dies.


What is Hydroponics?

In case you’re not aware, the term hydroponic is derived from a Latin word that means “working water”. To put it simply, hydroponics is an art that involves growing various types of plants without soil. If you’re like most people, the first thing that comes to mind when somebody talks about hydroponics would be a picture of plants with roots suspended into the water without using any type of growing medium.


Avoiding Root Rot in Hydroponic Systems

Detecting and identifying root rot can be tricky. When your plants get infected, their leaves and roots gradually wither until the whole crop itself dies from the lack of nutrients, which is a common symptom of many diseases.


What causes root rot in hydroponics?

One of the requirements in hydroponics systems is oxygen. Without it, your plants are basically on the road to death. On the other hand, lack of such is one of the major triggers for root rot, and it must be avoided at all costs.

Just like when planting in soil, you loosen up the ground so that your plants’ roots can have their required intake of oxygen. That is the case for crops grown in aqueous solutions as well. If they cannot breathe, they would not be able to grow.

Another agent for root rot is the temperature. The last thing you would want in your system are parasites that leech nutrients intended for your plants and infect the water during the process. In common terms, these fungi are called molds.

One of the best breeding grounds for these is warm and moist areas. For this reason, if the water temperature inside your reservoir is high, then you are susceptible to it. Something as minor as letting the solutions exposed to sunlight can already be a risk factor.


3 Useful Tips on How to prevent root rot in hydroponics

There is good news! Root rot in hydroponics can be prevented! Just follow these tips:

Tip#1: Use the right air pump

If you do not want root rot to affect your plants, you merely have to avoid its causes. If you need oxygen, keep the water bubbling by providing an air pump of appropriate size, and also give importance to proper ventilation in the room.


Tip #2: Maintain the temperature

The temperature should be maintained within the 70 to 80 degrees F range. Get rid of any materials that can make your system vulnerable to infections, and make sure not to disturb your crops while they are trying to grow.


Tip #3: Get rid of the rotten parts

However, if you failed in preventing the disease, then the rotten parts should be removed immediately. Cut them off as there is no chance of reviving them, and focus on the potential new growth instead. Fix your hydroponics system and eliminate the risks.


Why Give Greenhouse Gardening a Try?

Greenhouse gardening offers numerous benefits to greens aficionados who dare to take their gardening experience to the next level. Aside from acting as a shield against the effects of inclement weather, a mini, hobby, or semi-pro greenhouse can also serve as a protective layer that keeps harmful bugs and critters at bay.

What’s more, its enclosed structure allows you to control your plants’ growing conditions including the temperature, light, moisture, and ventilation of the greenhouse’s internal environment. With a controlled environment, you’ll be able to extend growing seasons and grow plants that aren’t native to your area.



No matter how well-informed you are about how to prevent root rot in hydroponics, you cannot completely eradicate the risks. Therefore, to avoid the worst-case scenario, you should be prepared to sacrifice the infected for the sake of others. While you’re at it, consider trying your hand at greenhouse gardening as well.


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