Introduction: Prevent Leggy Seedlings by Increasing Light Intensity

About: I am an electrical engineer graduated at Budapest University of Technology and Economics. Besides my work I also like to do simple DIY electrical projects at home and I decided to share these projects with the…

As you may already know and/or experienced, if you start indoor planting early, when weather conditions are not the best yet, your seedlings will be leggy and weak that looks unhealthy. The reason of legginess is that the seedling does not get enough sunlight, but the temperature is high enough indoors. The stems grow thin because the plant is reaching its leaves towards the light.

There are some options to provide more light for seedlings, but of course you can not bring it outdoors if there is too cold outside. One option would be to apply an artificial light for you seedlings. The disadvantage of this option is that these type of lights can be expensive compared to your plans (only for some seedlings per year).

Another option that works for me and I would like to share with you is to increase the intensity of the sunlight with some basic components. Your seedlings can get almost twice as much light with this solution and you can do it very fast and easily.


  • Your seedling
  • Plastic bottle or any similar thing that is flexible but waterproof
  • Aluminium foil
  • Glue, duct tape, scissors

Step 1: Cut the Right Shape From Plastic Bottle

If you are using a plant pot for your seedlings, the best option is to use a plastic bottle. You will be able to cut to 2 or 3 pieces from the plastic bottle that will fit on the side of the pot. I recommend to cut a shape that covers 1/3 part of the pot as you can see on the last image. It's height can be ~10 cm.

But if you grow your plants in a different shape, you can use anything that is flexible enough. If you want to cover the whole bottom of the window, it's also possible, see on the image at the end of this post. I recommend to use a waterproof material to be able to use it for a long time, but it's not necessary.

Step 2: Cut a Piece From Aluminium Foil

Since we want to have a reflective material, we have to cover the previously created component with aluminium foil. So cut a piece that is a bit larger than the base.

To have more homogeneous light, crumple the aluminium foil a bit and flat it again as you see on the image above. If you don't do this in case of a round plant pot, the reflected light will focus in one vertical straight in the middle of the pot, that can hurt your seedling!

Step 3: Stick the Foil to the Base Shape

Stick the aluminium foil to your base shape and cut it around by leaving a small border. After that fold back the remaining pieces to the back of the shape. I also used duct tape to stick this remaining piece around on the back of the shape.

Step 4: Place It Behind the Seedling

Now you have the reflective shape that will reflect homogeneously the sunlight back to your seedling. As you can see on the first image it also reflected the flash of my camera very intensively.

All you have to do is to place it behind your seedling in a vertical position.

Step 5: Place You Seedlings Back to the Window

Your seedlings will enjoy the increased sunlight, they will look much healthier.

Step 6: Different Variants

I also have some more seedlings in my other window and I grow them in smaller pots. To provide them more light also, I created a larger edition from my solution. I used a cardboard to have as large reflective surface as the bottom of my window. It is not as much efficient as the round surface, but also provides more light for my seedlings.

Indoor Plants Challenge

Participated in the
Indoor Plants Challenge