How To Use Grow Lights For Seedlings?


Into gardening? Are you looking to start your seedlings indoors? You’ll need the right to grow lights to get started, which means you’ll also want to learn how to use them properly. Here’s everything you need to know about how to use grow lights for seedlings, including the benefits of using these special types of bulbs, how to set them up, and tips on the best ways to maintain optimal growing conditions for your new plants!

Proper lighting is essential for successful seedling care because it will provide them with a good starting point. Seedlings become flimsy and willowy when they do not receive enough water and may not survive for long. This is one of the most frustrating aspects of gardening for newbies, but it’s a common issue that’s easily resolved. Using grow lights is the only thing that can save you from having willowy seedlings.

grow lights feature greenhouse
Using Grow Lights for Seedlings or Indoor Plants. Source: Homestead & Chill

What are Grow Lights?

Before moving into detail, let us first tell you what a grow light is.

Grow lights are a perfect tool for starting growing vegetables, herbs, and flowers from seed indoors. Grow lights keep indoor plants thriving and healthy, help grow microgreens, or provide ancillary light within a greenhouse. Plants rely heavily on light to carry-out photosynthesis and survive.

But how exactly should you use them? If you’re new to growing plants, we’ll show you how to use grow lights for seedlings.

What you need to know about using grow lights for seedlings:

Choosing The Right Light

The first step is choosing the right light. You need to ensure that you get a particularly designed light for seedlings. These lights are usually labeled as grow lights or plant lights. They emit a light that is similar to sunlight, which helps encourage seedling growth.

You can use a few different types of grow lights, including fluorescent, incandescent, and LED bulbs. We recommend getting LED lights because of their high efficiency and lack of overheating and thus damaging frail seedlings.

As for which light colors are best for seedlings, red and blue LED lights are the most suitable for optimal plant growth.

However, it is worth noting that different types of plants have different needs when it comes to growing indoors. Some plants require high levels of CO2, while others may need more intense levels of light intensity and heat.

Growing With LED Grow Lights

If you’re starting your seedlings indoors under grow lights, you may be wondering how to best use those lights to ensure strong, healthy plants. Here’s a quick guide on how to use grow lights for seedlings.

Go through the Instructions Manual

1) Read the instructions that came with the lights. The manufacturer should provide guidelines and tips for using their product.

Choosing the Right Medium and Growth Settings

Besides soil, the most obvious option, you can also use growth mediums like Rockwool cubes or clay pellets. However, if you plan on transplanting your seedlings outside into the ground later, you may be better off using regular nutrient-rich soil.

Choose a container or pot that can hold water and give your sprouting seedlings enough room to grow.

●      Temperature

We should also mention that besides the medium, you also need to regulate the temperature of your room. Generally, keeping temperatures around 50-60° F should be ideal. However, plants that usually grow in hot and humid conditions may need higher temperatures for ideal growth.

●      Moisture and CO2

You should keep the growth medium moist but not dripping wet. A surplus of water can hurt your plants just as a lack of water can. Again, the exact conditions that your seedlings need depend on the type of plants you are growing.

As for the air quality and CO2, keep your room moderately ventilated. Keeping your plants by the windowsill might not be the best thing if the air or wind outside can make cold drafts across your plant pots. Keep your plants in a corner and adjust the heating according to how much heat your light may emit.

Keeping your seedlings away from windows can also help prevent your seedlings from growing in the wrong direction. This is because plants grow towards the source of light. If the light they receive always comes in at slanting angles, as is the case with sunlight coming in from windows,

Planting the Seeds

Add your seeds or seedlings to the medium and cover with about 1 inch of soil. The distance from the seed to the surface of the growth medium should not be more than 2-3 times the size of the seed itself.

If you are using a tray, be careful not to place the seeds too close together. This is because the seedlings might use up the space and eventually need more room for further growth. This is even more important if you plan to keep growing your seedlings into plants indoors instead of transplanting them outside.

If you plant seeds directly rather than using seedlings, you will not need to use the grow lights immediately. Grow lights will come in handy once these seeds sprout and the green shoots and first leaves start coming out. These leaves have the necessary metabolic machinery to start photosynthesis, something that germinating seeds under the surface of the growth medium do not have.

Planting Home Plants Indoors. Source: Ambius

How close should my LED grow light be to my seedlings? 

After your seedlings sprout, you should keep them at a distance of about 2 inches from the surface of your seedlings’ pots.

Keep in mind that LED lights may not damage your plants as much as other types of lights can. Incandescent and HPS lights, for example, can make your seedlings especially prone to getting scorched. This is because these dangerous lights are less efficient than LED lights, making them convert more electrical energy into wasted heat waste. Not only is this relatively worse for the environment, but it can also disturb the growth and health of new seedlings.

So be extra careful if you use full-spectrum fluorescent or high-pressure sodium lights.

How long should I use my grow lights per day?

You should generally use your grow lights for about 16 hours per day. However, specific plants may require more or fewer hours, so we recommend looking up the daily sunlight duration required for particular plants. 

Some lights come with timers you can use to set the number of hours the light will stay on once you turn it on. If you get a grow light without a timer, you can just turn on the lights first thing in the morning and turn them off at night before you go to bed.

Hardening Off Your Seedlings

If you plan on transferring your plants outdoors after growing them with grow lights, you should harden them off before doing so.

Hardening off refers to acclimatizing the plants to the conditions outdoors. This is necessary because if the artificial conditions you provided your seedlings indoors with your grow lights do not match the conditions and light outside, your seedlings may go into shock.

So at the end stages of indoor growth with grow lights, you should wean your plants off the lights. Try placing the pots or the tray of seedlings under natural light and wind outside for a couple of hours every day. Dial up the hours as the days go by until you are sure that your plants can survive the whole day outside.

Re-nourishing the Growth Medium

After one set of seedlings are grown into plants or are ready to be transplanted, you have to ensure that the growth medium is rich enough in nutrients to support the next batch. You can renourish the soil or the growth medium of your choice by using suitable fertilizers. Keep in mind that you can choose from both tailored and general-purpose fertilizers.

Common LED Growing Setups

If you’re using grow lights to start your seedlings, you’ll need to set up a few things before you get started. Here’s a quick guide on standard LED growing setups. It can be intimidating when you look at all the options out there! Don’t worry, though. These are the most common types of LEDs and setups that beginners use. The important thing is to find the one that suits your needs best and get started!

In the first setup, you have an LED panel with a reflector in front of it to focus light onto plants in pots. These panels usually come with a power cord and plug but don’t require any additional parts. To create this setup, all you need is an area to place your pot or potting tray (any reflective surface will work) and plug in the panel! You can adjust the angle of the panel based on how close or far away from plants it is placed.

Secondly, you can use kits that come equipped with LED lights, found here, and a stand that you can use to adjust the height of the lights. Adjustable height settings like this can especially come in handy when you want to keep your seedlings growing until they are ready to harvest. Otherwise, you would have to adjust the height settings every few days or so, depending on your seedlings’ growth rate.

These kits usually also come with timers, so you do not have to worry about switching the lights on and off every day.

Tips and tricks for Fluorescent lights

  1. If you are using a full-spectrum fluorescent lighting system, turn or tilt your plants around at least once a week. This is helpful because the light from a fluorescent bulb is more intense in the center than at the ends, so every part of the plant should receive proper lighting.
  2. If you see that your fluorescent bulb has turned black, replace them. The change of color indicates that the bulb is old, and the light output may be less than it was before.
  3. Try replacing your bulb once a month because dust and dirt can accumulate and reduce the amount of light emitted.
  4. As the seedlings grow, raise your lamp to keep the lights about 2-4 inches above the plants.


In this article, we have guided you on how to use the grow lights for seedlings. You can get started and decide if you like it by using the above guidance on growing seedlings with grow lights. It can be challenging to understand indoor gardening and become acquainted with its minor differences from outdoor gardening. However, it can be a rewarding bonus for your gardening hobby once you start. It’s good to take a break from fear of insects, or the climate is good.

Frequently Asked Questions

Can grow lights cause eye damage?

Yes! Grow lights can cause eye damage. Therefore, avoid staring at them. UV light of any intensity can be harmful to our eyes. Blue light has also been linked to neural activity and circadian rhythm disruptions. Working with colored grow lights can make some people feel uneasy.

What should the color of my grow light be?

LED grow lights that are “full-spectrum” or “broad spectrum” are recommended for growing seedlings indoors. These can be used for houseplants, as well. It is because a full-spectrum light has a good balance of blue and red light and is the closest thing to natural light.

Is it possible for plants to receive too much grow light?

Plants cannot receive too much light. But, they can receive too much heat energy associated with light.

Should you use grow lights during germination?

You should use a grow light in the later stages of the germination process but earlier. Let’s briefly go over germination has a couple of steps which are as follows.

  1. The seed fills up with water.
  2. The seed grows a root for nutrient uptake from the medium
  3. The seed then grows a shoot so it can start photosynthesis using its leaves.

Step 3 is where you want to start using grow lights. This is because the seedlings can not use the light from your grow lights without their leaves.