Updated at: 23-03-2023 - By: Sienna Lewis

Is it necessary to use artificial lighting in a greenhouse for seed germination? It goes without saying that any garden needs adequate lighting. To summarize, there are many practical benefits associated with light.

The lighting will cast lovely shadows that visually expand the room. If the lighting is inadequate, people may feel sad and want to sleep. Mirrors, candles, windows, and other natural or artificial light sources may provide the best illumination.

Exactly what are you hoping to gain from this conversation? What you’ll pick up by the article’s end:

  • To what extent greenhouse lighting is necessary
  • Indoor lighting for seed starting: how to get started
  • Knowing if a plant is receiving too much light
  • If there’s too much sunlight in the greenhouse, what will happen to the plants?

Do I Need Grow Lights In My Greenhouse?

Absolutely, that is the correct response. Nonetheless, we urge our readers to make use of natural light whenever possible. Natural light is the best option for the greenhouse’s lighting. Grow lights are required if the greenhouse is being used for plant growth during the winter or if the greenhouse’s design and placements limit the view that is captured. Choose the correct illumination.

Using Grow Lights for Seedlings or Indoor Plants ~ Homestead and Chill

Insufficient lighting

Not enough light is one of the most common issues with greenhouse lighting. The lack of light could cause the plants to stretch, increasing in height as they reach upwards in search of illumination. If plants don’t get enough light, they may become leggy and flimsy.

Rather than going into developing leaves, fruits, and flowers, some of the plant’s energy may instead go into weakening the plant’s central support structure, the stems. Making sure the artificial bulbs have enough wattage is another important step in providing adequate lighting for your plants.

Too much lighting

What if there’s an excess of illumination, though? It’s possible that the plant will wither. If you’re going to be using artificial lighting, you’ll need to ensure that you’re using bulbs of the appropriate wattage. Having the light close by is also important. Plantlings need to have their roots no more than two inches from the light source.

Light is another factor that plants respond to because they need it in addition to water in order to make starch and oxygen. In the course of the night, the plant changes these into sugars for storage.

One of the main issues with greenhouse lighting is that it may need to be left on 24 hours a day to speed up the growing process. However, doing so endangers the plants’ health. Plants exposed to such intense light may wilt or burn. Plants need at least eight hours of nighttime darkness per day to stay healthy.

How To Start Seeds Indoors Under Lights

The proper delivery of light is crucial when germinating seeds indoors. Young plants, such as seedlings, require up to 18 hours of sunlight each day. During the winter months, seeds may need more light than usual.

Numerous garden centers sell lighting for plants for less than $100; combine this with a simple timer to automatically turn on and off the lights, and you have a cheap and efficient growing system.

Some seasoned gardeners are of the opinion that the sun porch’s window sill may not provide sufficient light for healthy plant growth. Artificial lighting is essential, and fluorescents provide the best quality light at a reasonable cost.

As your seedling develops and you move the lights closer to the plants, you’ll need a way to monitor their development as you do so. Keep the lights on for about 12 hours a day.

To what extent does the use of compost become mandatory? Not necessary since growth will initiate during the germination process. The only thing gardeners need to worry about is what’s in the seed.

How Do You Know If Your Plant Is Getting Too Much Light?

It is possible to tell if a plant is receiving too much light by looking for what are known as “symptoms of light exposure” among plant experts. Yellowing leaves, elongated stems, stunted leaf growth, and a generally dull green color are probably the most noticeable symptoms.

The leaves of a plant subjected to too much light may develop burned spots, fall off, and develop singed tips. If the plant is getting enough sunlight, it should have a pleasing, deep green hue. More than anything else, it’s important to put the plant’s symptoms in their proper context.

What Happens If Plants Get Too Much Light?

As a gardener, you should keep in mind that plants need sunlight. Use this as a general guideline.

Researchers have discovered defense mechanisms used by plants against the harmful effects of too much sunlight. It may also be used in the creation of genetically modified crops with the ability to thrive in a variety of lighting conditions.

When planting seeds in a greenhouse, is artificial lighting necessary? This is a common enough question that even expert gardeners might investigate it. Chlorophyll and carotenoid are two photocapturing molecules used by plants to obtain energy from the sun. But when plants are subjected to an excessive amount of sunlight, the molecules may absorb more energy than they can handle.

Research has not revealed how the plants manage to withstand the assault, so far.

Do Seeds Need Light To Germinate Or Not?

Even the most rudimentary gardener knows that seeds need light to germinate. When starting seeds indoors, you’ll need grow lights to simulate sunlight. Some seeds and plants, however, can germinate without exposure to light.

Light, water, and soil are the bare minimum requirements for plant life. All three of these are important to photosynthesis. Seeds need water, warmth, and air to germinate, and light is often helpful but not required. Seeds that need to germinate in the dark are sometimes stymied by the sun.

A lot of seeds can sprout without ever seeing the light of day. While the majority of seeds benefit from moderate exposure to UV light, some can also germinate when exposed to no light at all.

In addition, there are plants that thrive in the dark or under heavy shade.

What Do Seeds Require To Sprout?

In response to changes in its environment, such as the presence of water, oxygen, light, and nutrients in the soil, a dormant seed will begin to germinate and eventually sprout. Let’s take a look at what’s required to get a seed to sprout, starting with the basics.


While seeds do contain some moisture on their own, they need to be planted in wet soil in order to emerge from their dormancy and grow. The process of imbibition is initiated by the addition of water. Water fills the seed, activating enzymes that pressurize the seed coat and aid the seedling’s rise to the soil’s surface.

When starting seeds indoors, the soil moisture level must be just right. Various conditions are needed for the growth of various seeds. The germination of quinoa, for instance, only needs a minimal amount of water and only a thin layer of soil. As a result, before the seedlings emerge, the soil needs to be kept dry. The quinoa seeds will rot if you soak them in too much water.

Some seeds, like nasturtiums and sunflowers, have a tough seed coat that needs a lot of water to break through; in this case, if there isn’t enough water, the seedling won’t survive once it emerges. This is done to increase the likelihood of germination.

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In order to generate enough energy to emerge from dormancy, seeds require access to oxygen and adequate airflow. The sugar glucose plays a role in facilitating aerobic respiration, which explains this. Energy is released from food reserves in the seed at this time, necessitating oxygen intake.

Seeds can’t produce enough energy to grow even if they get plenty of water and carbon dioxide.

Is there a way to guarantee that seedlings receive adequate oxygen? One way we can aid seed germination is by learning how deep to plant them. Typically, you want to bury your seeds under a thin layer of moist soil.

When seeds like amaranth or mugwort are planted too deeply, the young plants are deprived of the oxygen they require for imbibition and the seeds are unable to reach the nutrients they need to germinate. This is due to the fact that the seed coat on these seeds is particularly delicate.

Some seeds, especially those with a very thin coating, can be planted directly on the soil’s surface without even covering them. Scarification, or scratching or striating the seed casing, helps some seeds with a thicker coat to germinate. Thicker-coated seeds can gain access to gasses like oxygen through a process called striation.

A common question among gardeners is how deeply they should bury their seeds. However, some seeds may not be able to survive if planted at the recommended depth of.25 inches, as is often recommended on seed packets. It is recommended that seeds not be planted any deeper than twice their diameter.

As was previously mentioned, covering may not even be necessary for smaller seeds with thinner seed coats. One more thing you can do to keep the soil’s oxygen levels up is to not compact it too much. Instead, do a light patting of the soil and watch the seedlings emerge.


Despite common belief, the correct temperature is more important than light when it comes to seed germination. The germination rates of the seeds play a significant role. High germination rates in a seed crop might make temperature regulation unnecessary.

Planting more seed when using seeds with a lower germination rate is necessary to get a good harvest. It’s preferable to try to prepare the ideal temperature conditions in advance so that seeds aren’t wasted.

If you want to make sure the weather is just right for your seeds to germinate, you should plant them when the time is right. Although many types of seeds thrive in the warmer temperatures of spring and summer, others do better when the temperatures drop in the fall. Some varieties actually need to be planted in the fall so that they can experience cold stratification over the winter and spring.

Seeds that don’t need to be planted directly into the ground can be started indoors on a heating mat placed beneath a tray. To germinate, most seeds need temperatures around 75 degrees Fahrenheit. Heat mats for seed starting can increase the temperature of a seed tray by 10 degrees. Consequently, a greenhouse or an indoor location with a constant temperature of around 65 degrees Fahrenheit would be suitable.

Some seeds need to be planted at a specific depth and with a certain amount of moisture before they will germinate, and you can only provide them with what they need if you follow these guidelines.

The right amount of light exposure can sometimes be enough to warm seeds. However, this process may be fatal for seeds planted too shallowly.

If you want to know how fussy you need to be about the sprouting process, it’s best to keep up with the requirements for seed sprouting.

And Now For Light!

Most commercial seeds have been selected for their ability to germinate regardless of whether or not they receive light. However, there are those who require sunlight. There will be further discussion of the seeds that do and do not require light for germination.

A century and a half has passed since scientists began investigating how much light seeds need to germinate. Kinzel (1926) conducted experiments with varying heat and light controls and discovered that some seeds require light while others require darkness in order to germinate.

Sometimes it’s not necessary to bury people who have special lighting needs. Because of this, seeds can get the light they need to germinate. Those that must have complete darkness to germinate may benefit from being planted deeper in the ground, where they will be shielded from the sun’s ultraviolet rays.

Is Light Even Necessary?

Every single seedling relies on light for proper root development. They will become gangly from reaching for an absent light source. It’s impossible to generalize about how much light a seedling needs.

Those who reach maturity with less dependence on sunlight have a reduced light requirement. When seedlings are subjected to excessive light or heat, they wilt and die.

However, not all seeds require exposure to light before they can sprout. This information is critical for determining whether you should start your seeds indoors or in the garden. Let’s take a look at photosynthesis and see why some seeds require light to germinate while others don’t.

Plant Photoreceptors

Phytochromes in plants are the key to figuring out which seeds need light and which need dark to germinate. Plants’ phytochromes are light receptors that interact with red ultraviolet light to facilitate photosynthesis.

Plants have two types of phytochromes, type I, which respond to far-red UV light, and type II, which responds to red UV light.

Type II phytochromes allow trees in the rainforest canopy to tolerate high levels of sunlight and red light. When leaves in the canopy trees take in this light, they reflect far-red light both upward, back toward the light source, and downward, to the forest floor plants. These plants at the forest floor contain type I phytochromes and are more susceptible to being damaged by exposure to visible light than to the invisible far-red light.

This question can only be answered positively in the case of plants with leaves. Light is required, but the quality of that light is crucial. Some plants, such as herbs, are particularly sensitive to light, and exposure to the wrong wavelengths can be disastrous. Equally true is the inverse statement. When all other conditions are met, plants that receive the appropriate light type flourish.

How Much Light Is Enough

Seeds that require light to germinate can be started under grow lights or in a south- or north-facing window, depending on your latitude.

Alternatively, seeds can be sown directly in a thin layer on the soil if the weather is warm and sunny enough. Light and heat can also be provided by placing a greenhouse in early spring sunlight.

Without the aid of light, some seeds may take longer to germinate than others, so it’s best to sow them in trays. Try enclosing them in black plastic to block out any light. When covering, keep an eye on the thermometer to make sure it doesn’t drop below the germination temperature.

Humidity can be increased by placing plastic over your tray, and the plastic will also trap heat to keep the soil warm and moist.

Seeds That Need Light

We won’t list every possible vegetable because most of them need UV light to germinate. Here, however, are a group of plants that are typically grown from seed, but which cannot germinate unless exposed to light. All of the plants mentioned here have exceptionally small seeds encased in papery membranes.

  • Lettuce is a great example of a seed that can germinate in your garden without being buried. If you want your lettuce to sprout, you’ll need to expose the seeds to light. They can be dusted onto soil or vermiculite and then given a light covering of the same.
  • Similar to how lettuce seeds germinate when sprinkled on top of the soil, carrot seeds need to be exposed to light in order to grow. Plant seed in a row on soil or vermiculite and cover with the same medium as you would for lettuce.
  • Sunlight is essential for rose seed germination. If you water the soil sufficiently, you should see seedlings in about six weeks.
  • Some species of salvias prefer low light conditions, so it’s important to research the different types available. You should keep the soil moist after direct sowing in the garden, but you shouldn’t wash away the tiny seeds.

Plants That Prefer The Dark

We’ve learned that some animals and plants simply thrive in the shadows. The thick seed coats of many of these popular vegetable garden varieties germinate best in the cool, damp conditions found deep in the soil.

  • Gardening with nasturtium has many advantages. Nasturtium seeds should be sown directly into rich organic soil and covered to a depth of three times their diameter. You’ll see cheerful seedlings with round leaves emerging soon after.
  • The growth of calendula is stunted by direct sunlight. In order to protect these worm-like seeds from drying out, bury them under an inch of nutrient-rich soil that is out of direct sunlight. When growing calendula, be sure to water consistently.
  • Grow the biggest sunflowers in a hole three times as wide as they are, and cover the soil with plastic before the seeds germinate for the best results. To speed up the germination process, remove the plastic and place the seedlings in bright light as soon as the first true leaves appear.
  • A large onion has a thick seed coat that prevents it from germinating when exposed to sunlight. During the germination process, long nights are actually preferred. They can be started indoors under plastic, and then moved to a bright location once they have sprouted.

Seeds That Don’t Really Care

The following vegetation can grow with or without sunlight. They have seeds that are a size in between those of the large and small varieties listed above.

  • Tomatoes can be started early in the year indoors or out, and depending on where you live, you could have a harvest of tomatoes lasting until the middle of fall.
  • Personally, I have never been able to keep a cucumber seed from germinating. They can germinate in almost any soil environment. Seeds from your preferred type of cucumber will have the best chance of germinating. When starting cucumber seeds, do not add vermiculite.
  • Eggplant: while light isn’t strictly necessary for eggplant seed germination, it certainly doesn’t hurt.
  • Direct sowing of zinnias in a sunny location with a minimal amount of soil cover is ideal. You shouldn’t start zinnia seeds indoors because the young plants are vulnerable to transplant shock. They go wonderfully with your lettuce and tomato plants.

Begin with manageable steps if you need to gain perspective on the big picture. Sow a variety of seeds and make sure to keep tabs on their needs. Maintain a close eye on your own development. Over time, you’ll gain insight into what works and what doesn’t under your specific circumstances.

Using Grow Lights for Seedlings or Indoor Plants ~ Homestead and Chill

Common Mistakes Made While Growing Seeds Indoors

Starting seeds indoors can save a lot of money, especially if they mature into healthy plants. It can be difficult to cultivate seeds indoors, though. The odds of success will increase dramatically if you avoid making these typical errors when starting seeds.

Not Supplying Enough Light

To mature into robust plants, seedlings require a great deal of light. You probably do not have enough natural light in your home to grow healthy seedlings, despite what other people may tell you. In most cases, not even a south-facing window will do. A suitable amount of light for seedlings can be achieved, however, with the help of artificial lighting. Grow lights are artificial illumination methods specifically created for plant cultivation. As an alternative, you could save money by installing two large fluorescent shop lights, one with a warm bulb and the other with a cool bulb.

Using chains, you can easily move the lights up as the seedlings get taller. Place the lights as close as possible to the seedlings (about 2 to 3 inches away) without touching them. At the time of their appearance, seedlings require 12-16 hours of daily light. Put the lights on a timer so they turn on and off without your intervention.

Applying Too Much or Too Little Water

The success or failure of seedling development depends on the amount of water provided. One of the trickiest parts of starting seeds is making sure they get enough water. Due to their vulnerability, seedlings require careful attention when watering. Water the sterile seed-starting medium just until it’s moist but not dripping.

Here are some suggestions that can help you improve your chances of success:

  • Put together a makeshift greenhouse by covering the container in plastic until the seeds sprout.
  • Do not overfill the container; instead, water the bottom so the seedlings can drink through the drainage holes. By taking this precaution, you reduce the likelihood of watering too much. After 10 to 30 minutes of slowly adding water, test the soil with your finger to make sure it’s moist all the way to the top.
  • Always make sure to check the soil moisture level once a day.
  • Purchase a seed-starting system that includes its own watering mechanism.

Starting Seeds Too Soon

Exposing plants to cold air or soil can be stressful for them, as many of them are sensitive to the cold. The owner of the Kennebec Flower Farm, Chas Gill, agrees that starting seeds too early is a common mistake. Pests and diseases can do more damage to stressed plants. Four to six weeks after seeding, most plants are ready for the outdoors.

Planting Seeds Too Deeply

The ideal planting depth for seeds varies. However, there are seeds that must have total darkness in order to germinate, and there are also seeds that must have exposure to light in order to do so. 1 The seed packet typically includes instructions on how deep to plant the seeds. If there is no guidance on how deeply to plant the seeds on the packaging, a good rule of thumb is to do so at a depth of two to three times their width. It can be difficult to judge the depth of something; if in doubt, go with less.

If you’re using a seed starting medium, make sure the seeds are in contact with it but not covered, as this will allow light to reach them and encourage germination. Firm up the soil medium by pressing down gently. The seed should be placed on top of the medium and then lightly pressed down while still being exposed.

Moving Seedlings Outdoors Too Soon

As they are still developing, seedlings do not benefit from being treated harshly. Either they will perish instantly or they will weaken and be unable to thrive. When they’re young, even the hardiest plants require a lot of TLC and protection.

The process of hardening off begins when your seedlings reach the appropriate size for planting outdoors. 1 Gradually exposing them to wind, rain, and sun helps harden them up for the outdoors. Hardening off your plants involves gradually exposing them to the elements, and while this may seem like a daunting task, it is actually quite straightforward. You should harden off your seedlings by exposing them to outdoor conditions for an hour on the first day. For the next six to ten days, do this: Spend a little more time outside each day. Depending on the weather and how delicate your seedlings are, you’ll have to use your best judgment. When the weather is cool or wet, you should shorten the length of your hardening-off session.

Sowing Too Many Seeds

If you are just starting out, it is best to plant a few modest seeds to see what happens. It will be difficult to raise the young plants to maturity if you plant more seeds than you can care for. When the weather outside is warm enough, you can sow seeds directly into the ground or into outdoor containers, depending on the type of plant you want to grow.

Keeping Seeds Too Cool

In order to germinate, most seeds need to be kept at a warm temperature, between 65 and 75 degrees Fahrenheit. The top of the refrigerator is a popular spot to keep seeds at a warm temperature so they can germinate. There is also the option of purchasing seed-warming mats to place beneath the seed trays. When a seedling first emerges, it can’t handle extreme temperatures, but it can handle moderate ones. Make sure the plants are kept between 65 and 75 degrees and that the light source, whether it be natural or artificial, generates enough heat to maintain that temperature.

Failing to Label Seeds

When sowing seeds, label the containers so you can tell at a glance which ones contain each type of seed and when the seedlings inside will be ready to be transplanted. Mark the planting date and plant name on popsicle sticks or plastic plant markers using permanent ink pens for each variety of seed planted. Plant labels should be buried near the edge of the tray or pot.

Giving Up Too Soon

It’s not always easy to get seeds going. But when you eat a tomato you grew in your garden or admire the flowers you tended from seed, you’ll know that your hard work was worth it. It takes time, effort, and care to nurture plants from seedling. It’s important to keep going even if you make some mistakes. The benefits justify the effort required to achieve them.


Do you need grow lights to start seeds in greenhouse?

Place the seedlings in the brightest part of the greenhouse if possible. When germinating seeds indoors or in a greenhouse, many farmers rely on artificial lighting. If your seedlings have ever developed long, slender stalks, you have witnessed the effects of poor lighting.

Do I need a grow light to start seeds?

Growing strong and healthy plants from seed requires a lot of light exposure. Lights should be held 2–3 inches from the young plants to maximize their growth. Lights should be left on for 12-16 hours a day when seedlings first appear.

Do seedlings need darkness?

It’s true that your seedlings require a lot of sunlight in order to flourish, but you should also give them some time in the dark. It is recommended that seedlings be placed in a south-facing window, where they will receive between 14 and 16 hours of light per day.

Is a grow light necessary?

Indoor plants need more light than their outdoor counterparts. Most edible plants require anywhere from 14 to 18 hours of light per day when grown under artificial lighting. However, resist the urge to keep the lights on around the clock; plants need at least six hours of darkness every day.

What color light is best for germinating seeds?

Research conducted by Thompson & Morgan found that red light stimulates germination while blue light inhibits it. This occurs because a plant pigment called phytochrome within the seeds reacts negatively to the red light. However, blue light may also be necessary if the plants are located below a dense leaf canopy.

When should seedlings get light?

As soon as you see a single sprout, turn on your grow lights (or place your seedlings under lights). Upon emergence, many seedlings will immediately begin reaching for the light in an effort to maximize their rapid rate of growth. So make sure they have plenty of it to start.

Why do seeds germinate better in the dark?

The light form normally deteriorates to the dark form after a few HOURS, but is converted back again after a few MINUTES in the light. Therefore, a seed at the soil’s surface receives enough light to keep the dark form of phytochrome low for an adequate amount of time to prevent the germination initiation from occurring.

Do seeds grow in the dark?

The majority of seeds benefit from being kept in the dark during the germination process. Although light is essential for a seedling’s growth, it may slow down the germination process if it is present too early.

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Is a windowsill enough light for seedlings?

Tricks. Most seeds can’t germinate without heat, though. Plant your seeds on top of a refrigerator or near a radiator, or anyplace else that stays consistently warm. As soon as you see any sign of green above ground, transfer them to the sunniest windowsill you have.