How To Start Seeds Indoors With Grow Lights: Ultimate Guide - Swipe Garden (2024)

Growing your plants indoors with grow lights can make all the difference. From choosing the ideal location to the perfect soil mix, and even down to the type of light you should use. This article will teach you the way to start seeds indoors with grow lights to give your seedlings healthy growth.

Table of Contents

How To Start Seeds Indoor Under Grow Lights?

Here we will walk you through the steps to grow indoor seeds under a grow light. We will cover everything through 12 steps below:

Step 1: Choosing the right spot for seed starting

Before you start planting, decide where you’ll set up and the type of light, some require sockets while fluorescent lights have to hang above your trays. Make sure to have seed trays for planting as well.

Tip: Seed trays are easy to use for beginners. The cells usually allow water in and roots to grow through. For a quick DIY option, you can use egg cartons with a small drainage hole at the bottom, or even empty toilet paper rolls.

How To Start Seeds Indoors With Grow Lights: Ultimate Guide - Swipe Garden (1)

Trays of vegetable seedlings under grow light

Step 2: Preparing the soil

You loosen the soil mixture and make it slightly damp. Ensure there are no dry spots in this soil mix.

Step 3: Filling up the pots

Now, fill up your trays or pots with the soil mixture and then plant seeds over 2/3 of the surface area. After that, lightly tap the tray onto a table so the soil settles. Next, use your hand or a small board to lightly press down on the soil, avoiding compaction so it stays airy.

Step 4: Planting the seeds

You follow the instructions on the seed packet for specifics. Some seeds may need a period of cold stratification or soaking beforehand. Others may require a dark environment to germinate, while some need light to grow.

Step 5: Finishing up planting

Once the seeds are in, add some more damp soil on top and press lightly. Note that small seeds require less soil covering. Refer to your seed packet instructions for the correct amount of soil to add.

Tip: Even if your soil was pre-dampened, mist the top layer lightly. This will keep the soil moist and help with seed-to-soil contact.

Step 6: Label everything

To know which plant is growing where it’s essential to label each tray or pot. You can use popsicle sticks and markers to write the plant name and the planting date. Place these labels near the edge of the box or tray.

Step 7: Creating the environment

Now, you cover the trays with clear plastic to retain heat and moisture. Then, move the trays to a warm spot, away from drafts. The ideal temperature for most seeds is between 65 and 70°F. For added warmth, you could use special seed-heating mats under the trays but remember, this will require more frequent watering.

Step 8: Watching the seedlings grow

As soon as the seedlings start appearing, you remove the plastic cover and place the trays in indirect light (like under Grow lights). The seedlings will begin to develop two leaf-like structures called cotyledons.

Step 9: Set up grow light

Keep your light as close to the seedlings as possible without touching them (around 2 to 3 inches). When the seedlings emerge, you should keep the light on for 12 to 16 hours each day. To save time, you also use a timer to automatically turn the lights on and off.

The secret to robust seedlings isn’t just the duration of light they receive, but the quality of light. Investing in a good grow light is like giving your plants a head start in growing season.

Step 10: Keep seedlings moist

In this step, you must keep the seed-starting environment sterile and consistently moist but not wet. Moreover, remember to check the soil moisture at least once a day to ensure it’s not drying out. Additionally, maintaining the right moisture level also minimizes the risk of diseases like damping off by watering from below.

To water, you should place the seedling tray on a plate and pour a small amount of water into the plate for about 10 to 30 minutes. Then let the seedlings absorb water through the drainage holes or the foam material of the container. To check moisture, touch the soil surface with your finger. After checking, continue by moving the tray out of the plate and placing it back in its original position to receive light.

Step 11: Start feeding

As the seedlings grow and develop leaves, they will need food to continue growing. At this stage, you should use liquid plant food but dilute it to half-strength as stated on the package. The feeding frequency is once every two weeks.

Step 12: Give them a new place

At the growth stage, if the plants are too large for their small pots, move them to a larger pot. Now you can use regular potting soil. If multiple seedlings are in the same pot, remove the weaker ones.

How To Start Seeds Indoors With Grow Lights: Ultimate Guide - Swipe Garden (2)

Seeds growing indoors under fluorescent lights

Why Should I Seeds Under Grow Lights?

Plants need special colors of light to grow well, especially red and blue light. Normal white lights don’t have these special colors. That’s why it’s good to use grow lights that have the full range of colors like the sun or just red and blue lights. This helps plants start strong.

You can find different shapes and kinds of grow lights. Some are LED lights that go in regular lamp sockets. Others hang from the roof or fit in special stands for seedlings. There are many old-style grow lights available today, but they use more power than modern LED or tube lights.

How Far Away Should Seedlings Be From A Grow Light?

You should keep seedlings 2-4 inches from soft lights like fluorescents, and 16-36 inches from strong lights like LEDs or HIDs. If you put them too close, they might get burnt. Besides, if you put them too far, they grow weak. Additionally, you also consider other things:

  • Plant type: Different plants need different light. Some, like tomatoes, need more and should be closer. Others, like herbs, need less and can be further away.
  • Light power: Brighter lights can be further from plants because they give off more heat and light. And weaker lights should be closer.
  • How you grow: If you’re using water-based growing (hydroponics), lights should be closer. For normal soil growing, they can be a bit further away.

Benefits of Growing Seedlings Under Grow Lights

First and foremost, the right grow lights for indoor plants ensure that they grow up to be strong and healthy. This increases their survival rate, meaning you don’t need to plant extra seeds to make up for any that didn’t make it. Therefore, you can save on seeds, soil, and the time it would take to replant.

Besides improving plant health and minimizing waste, grow lights also make the whole process more flexible for you. By using a timer to control the light cycles, freeing you from the chore of constant monitoring. Moreover, the use of grow lights means you’re not restricted to placing your seedlings in rooms with ample natural sunlight. Thus, you can place them anywhere in your home, giving you more freedom and flexibility in your gardening endeavors.

How To Start Seeds Indoors With Grow Lights: Ultimate Guide - Swipe Garden (3)

Growing seedlings of tomatoes under LED light

Conclusion

Grow lights offer a variety of benefits for starting seeds indoors. They can help ensure that your seedlings grow up to be strong and healthy, increase their survival rate, and save you time and money. With this step-by-step guide, you’re well on your way to becoming an indoor gardening pro.

FAQs

How many lights do I need to start seeds?

For plants that love lots of suns, like vegetables, you’ll need around 2000 to 3000 lumens per square foot. If you’re just starting one standard seed tray, a single grow light with 3000 lumens will do the job.

Is it okay to keep the grow lights on for 24 hours for the young plants?

No, don’t keep the lights on for a full 24 hours. Your seedlings need around 14 to 16 hours of light each day, but they also need some darkness to rest.

What sign to tell your seedlings are lacking light?

If your seedlings are stretching out and leaning towards the light, that’s a sign they need more light and you have to move the grow light closer to them.

How To Start Seeds Indoors With Grow Lights: Ultimate Guide - Swipe Garden (2024)

FAQs

How do you set up an indoor seed starting system? ›

How to Start Seeds Indoors in 4 Easy Steps
  1. Fill a large bowl with seed-starting mix and mix in a little water to evenly moisten the soil. ...
  2. Place your seed tray inside the drip tray and fill each cell to just below the top with soil.
  3. Sow your seeds. ...
  4. Cover the tray and place it under your lights on the heat mat.
Feb 10, 2023

How do you plant seeds first indoors? ›

How to Start Vegetable Seeds Indoors
  1. Moisten your potting mix.
  2. Fill your seed trays or containers with potting mix. ...
  3. Using a small dibber or pencil, poke holes in the soil of each cell or container. ...
  4. Label your trays.
  5. Bottom water your seed trays/containers. ...
  6. Set seed trays aside to germinate.
Apr 24, 2020

What color of light is best for starting seedlings? ›

Light color

Typically, plants use more blue and blue-green light when they are seedlings, and more red light later on in their life cycles when they begin to flower and produce seeds.

How close should lights be to seedlings? ›

1) Amount of light

Don't worry- you don't need one for this if you're using LED bars or fluorescent bars. Just remember the following distances. LED bars (like Philips): 8-12 inches away from seedlings. T5 fluorescents: 5-6 inches away from seedlings.

Do seeds grow faster in light or dark? ›

Most of the seeds germinate best in dark environments. The presence of light tends to inhibit their growth. The light decomposes carbonic acid gas and expels oxygen which leads the seed to harden. These gases are key factors that promote germination.

Should grow lights be turned off at night for seedlings? ›

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.

What happens if you leave grow lights on 24 hours a day? ›

Plants absorb light and convert it into energy. At night, when everything goes dark, the respiration converts this energy into carbohydrates for later use. It means that exposing plants to light 24 hours a day can prevent respiration from occurring, which is also not conducive to healthy plant growth.

What is the best seed starter method? ›

Trays and cell flats are the seed-starting method of choice on most large vegetable farms for several reasons: They are very quick to fill. They can be moved around easily.

What is the best system to start seeds indoors? ›

The best and most earth-friendly option is to use a soil blocker. Soil blocks are more work up-front, but save time in the long term because you just plant the whole thing, like a peat pot, but with zero root restriction.

How many seeds per hole when starting seeds indoors? ›

Most seeds prefer a depth of about 2 times their length. The tiniest seeds can be sprinkled directly on the surface. Cover the seeds with a thin layer of soil. Plant about 3 seeds per hole (more if using older seeds) and once they germinate, thin down to leave only the strongest seedling.

What is the best medium for starting seeds? ›

Edmund's recipe for a good basic pasteurized medium for growing seedlings is a mixture of one-third pasteurized soil or compost, one-third sand, vermiculite or perlite, and one-third coconut coir or peat moss.

What month is best to start seeds indoors? ›

Mid-March is the best time to start many vegetables and annual flowers indoors for transplanting outside once the threat of frost has passed.

Can seedlings get too much light? ›

If seedlings are turning brown, it can be a sign of too much light,” Fiene said. After about two months indoors, when you see roots coming outside of your seedling trays, it will be time for you to start hardening off your young plants.

Can I start seeds inside without a grow light? ›

Seeds don't need light to germinate. However, once they have emerged from the soil, they need light right away. Using a heat mat may help speed up germination. Growing space takes up room in your house.

How long does it take for seeds to sprout indoors? ›

Germination speed mainly depends on the temperature of your room. The warmer the environment, the faster the germination. The best average temperature to grow your plants is 18 to 24 °C (64 to 75 °F). Usually, it takes around 1 to 2 weeks to germinate.

Do seedlings need darkness? ›

Attach them to a timer set to 12 hours of light per day. The seedlings will thrive, thinking it's later in the spring. That being said, plants do need some darkness to grow, so make sure the timer also turns the lights off.

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