How to Start Seeds Indoors Without Grow Lights (6 Simple Steps You Can Follow!)

Not everyone has the space for expensive grow lights or the budget to invest in them. 

But that shouldn’t stop you from starting seeds indoors!

The good news is, you don’t need grow lights to successfully grow healthy seedlings. 

By using natural light and a few basic materials, you can easily start seeds indoors.

Not only does it save you money, but it also simplifies the process, making it accessible for anyone (even in small spaces).

In this guide, I’ll show you how to start your seeds without costly equipment and share practical tips to help you grow your own plants indoors, hassle-free.

And if you're new to indoor gardening, be sure to check out our Indoor Gardening for Beginners for more ideas and tips on growing plants at home.

What Do I Need to Start Seeds Indoors Without Grow Lights

You don’t need expensive or fancy materials to start seeds indoors. In fact, many of the materials are simple and affordable, and you may already have them at home.

All you need are:

• Seed Trays (72-cell trays are a good option)
• Bottom Tray (to catch excess water)
• Humidity Dome (clear plastic cover for moisture)
• Seed Starting Mix (light, well-draining soil)
• Watering Can
• Spray Bottle
• Dibble (tool for making holes in soil)
• Seeds (organic seeds are a great choice)

With just these basic items, you can start growing your seeds indoors quickly and easily.

Where Can I Find the Best Light for My Seed Trays?

You’ll want to find a spot in your home that gets plenty of natural light.

A south-facing window is your best option since it receives the most direct sunlight throughout the day.

But if you don’t have a south-facing window, don’t worry. East- or west-facing windows work well too, giving your seeds a good amount of sunlight in the morning or afternoon.

Windowsills are perfect for this, but you can also set your seed trays on tables or shelves near the window. Just make sure they’re getting enough light (aim for at least 6–8 hours a day if possible).

Avoid areas shaded by heavy curtains, trees, or buildings that block sunlight.

Since you don’t have grow lights, natural light is the cheapest yet most effective solution for starting your seeds indoors—take advantage of that!

6 Simple Steps on How to Start Your Seeds Indoors

Starting seeds indoors doesn’t have to be complicated or hard—it’s actually easier and simpler than you think.

To help clear your mind and give you even more ideas, here are some easy steps you can take.

#1. Prepare Your Seed Trays

If you’ve already decided where to place your seed trays (perhaps on windowsills), it’s time to prepare your seeds and set them in the trays.

Start by filling your seed trays with seed-starting mix. This mix is light and drains well, helping your seeds grow strong roots.

If you’re using a 72-cell tray (a common size), fill each cell with soil, but leave a small gap at the top to allow space for watering.

Once the trays are filled, lightly moisten the soil with a watering can or spray bottle. The soil should be damp, not soaking wet.

For seeds like tomatoes, which require a bit more moisture to sprout, ensure the soil is evenly damp.

If your trays don’t have drainage holes, place them inside a larger tray to catch any excess water and prevent messes.

#2. Plant Your Seeds

For the next step, use your finger or a dibber (a small tool for making holes) to create small holes in the soil where you'll plant the seeds.

How Deep Should I Plant the Seeds?

Typically, the general rule is to plant seeds about 2–3 times their size deep in the soil. To be safe, follow the instructions on the seed packet.

For smaller seeds, like lettuce or herbs, you can simply sprinkle them on the surface or lightly cover them with a thin layer of soil.

Larger seeds, such as beans, require a deeper hole (around 1–2 inches).

How Many Seeds Should I Plant per Cell?

Plant 2–3 seeds per cell to ensure at least one seed germinates.

If more than one seed grows, you can thin them out later, leaving the strongest plant in each cell.

If you’re planting multiple types of seeds in the same tray, be sure to label each section (using plant markers or tape) so you can keep track of what’s planted where.

This is especially helpful when you’re growing a mix of plants like basil, peppers, or flowers.

Once your seeds are planted and your trays are ready, place them in a bright, south-facing window. 

Like what I’ve mentioned, this is the best light source for indoor seedlings.

#3. Water and Keep the Soil Moist

I always emphasize in our gardening articles not to overwater or underwater your seeds (or even your grown plants).

Both overwatering and underwatering can negatively affect your seeds, so take the time to find the right balance when watering them.

How Often Should I Water My Seed Trays?

Water your seed trays gently every day, or whenever the soil feels dry.

You can use a watering can to water deeply, ensuring the water reaches the bottom of each seed cell.

If you prefer a gentler approach, use a spray bottle to mist the surface lightly.

Remember, the goal is to keep the soil damp—like a wrung-out sponge (not too dry, but not puddling with water either).

Should I Use a Humidity Dome?

Definitely, yes! A humidity dome can be really helpful. It creates a warm, moist environment that promotes seed germination.

The clear plastic dome traps moisture and helps maintain a stable temperature, which is perfect for your seeds.

After planting your seeds, place the humidity dome on top of the tray. Once the seeds start to sprout, remove the dome to allow the plants to breathe and grow stronger.

#4. Care for Your Seeds as They Sprout

As your seeds begin to sprout, it’s important to keep an eye on them. Check your seed trays daily to ensure the soil stays moist (but not soggy).

If the soil starts to dry out, water lightly. Using a spray bottle is a good option to avoid flooding the soil, which could drown the seeds.

Besides watering, temperature is also crucial. Keep the seedlings in a place that stays warm but not too hot. If the room gets too chilly, the seeds may not grow well.

On the other hand, if the area is too hot, the seedlings might dry out or stretch too much while trying to reach for light.

A steady temperature of around 65–75°F (18–24°C) is ideal.

What Should I Do Once My Seeds Start to Grow?

Once your seeds start sprouting (you’ll see little green shoots emerging from the soil), it’s time to remove the humidity dome.

This will allow your seedlings to get fresh air and reduce the risk of mold or mildew forming.

You’ll also want to place the seedlings in a spot where they can get as much light as possible.

If the seedlings start leaning or growing toward the window, it’s a sign they’re not getting enough light.

In this case, rotate your trays regularly (about every day or two) so each plant gets an even amount of light and doesn’t stretch too much on one side.

This is especially important if you only have one window for light, and it’s not evenly illuminating all your trays.

#5. Thin Out Your Seedlings

After about 1–2 weeks, when your seedlings are big enough to see clearly, it’s time to thin them out.

If you’re growing microgreens indoors, thinning usually isn’t necessary, as they are harvested at an earlier stage and don’t require as much room to grow.

Thinning involves removing the weaker seedlings so the strongest one can thrive.

This helps prevent overcrowding and ensures the remaining plants have enough space and nutrients to grow strong and healthy.

How Do I Thin My Seedlings?

To thin your seedlings, use a pair of clean scissors to gently snip the weakest seedlings at the soil level.

It’s best to cut them rather than pulling them out by hand, as pulling can disturb the roots of the seedlings you want to keep.

Make sure to leave the healthiest seedling in each cell.

If you planted multiple seeds in each hole (to increase the chances of successful germination), leave just one plant per cell to give it the best chance of growing strong.

#6. Hardening Off Your Seedlings

Hardening off is the process of gradually acclimating your indoor seedlings to the outdoor environment.

If you move them directly from your warm indoor space to the garden, they could experience shock from the sudden changes in temperature, wind, and sunlight.

How Do I Harden Off My Seedlings?

Start by taking your seedlings outside for one hour on the first day. On the second day, leave them out a little longer, increasing the time by 30–60 minutes each day.

Continue this process until the seedlings can stay outside all day.

Initially, place your seedlings in a shady spot to protect them from direct sunlight. Young plants can get scorched if exposed to too much sun too quickly. Gradually move them into more sunlight each day to help them acclimate.

Once you transplant them, understanding how to water transplants properly can greatly affect how well they settle into the garden.

By the end of the hardening-off process, your seedlings should be ready to handle outdoor conditions like wind, sunlight, and temperature changes without getting stressed.

What Should I Do If My Seedlings Are Leggy?

If your seedlings are leggy, it means they’re stretching to reach for more light. This happens when they don’t get enough sunlight, causing them to grow tall and thin instead of strong and stocky.

To fix this, move your seed trays to a brighter spot, ideally near a window that receives plenty of direct sunlight.

If that’s not possible, rotate the trays more often to ensure all the seedlings get sufficient light on every side.

How Do I Prevent Mold or Mildew?

Mold and mildew can appear if the environment is too damp or lacks adequate airflow around your seedlings. This is more likely to happen if the humidity dome is left on for too long or if you’re overwatering.

To avoid it:

• Remove the humidity dome once your seeds have sprouted to allow fresh air in.
• Make sure your seed trays have good drainage (holes at the bottom) so excess water can escape.
• Don’t overwater.

If you notice any mold or mildew, gently wipe it off with a paper towel or cloth. Adjust your watering habits and consider moving the tray to a location with better airflow.

Pro-Tip: Use Reflective Surfaces to Boost Light

If your window doesn’t get enough direct sunlight, or you want to maximize the light available, try placing a reflective surface (like aluminum foil, white poster board, or even a mirror) around your seed trays.

This will help reflect light back onto your seedlings, giving them more exposure to sunlight without the need for extra equipment.

Take your time, enjoy the process, and relish the joy of watching your plants grow from tiny seeds into flourishing vegetables, herbs, or flowers!

Frequently Asked Questions (FAQs)