How to Build a DIY Seed Starter Box with Leftover Materials

Want to start seeds without buying expensive gear? This DIY seed starter box was made with scrap materials and no budget. Here’s how I built it—and how you can too.

Starting seeds doesn’t need to be complicated or expensive. I put together this little seed starter box using leftover wood and things I already had around the house. No fancy tools, no exact measurements—just a bit of improvisation and a need to get some seedlings going.

This is for anyone who wants to experiment with starting their own seeds but can’t—or doesn’t want to—invest a lot of money into heating mats, shelving, grow lights, and so on.

 

That said, a small caveat: your results may vary depending on your climate. I live in a frost-free environment and can start all my seeds in this box year-round. If your growing season is short, you might need to adjust the box’s placement for better sun exposure and protect it from cold snaps.

DIY seed starter box made from scrap wood

Materials I Used to Build the Seed Box

I built the frame using leftover planks from an old project. The size really depends on your available space and materials. I used an old seedling tray to guide the dimensions. The box ended up 90cm x 70cm. With the back 29cm high and the front 14.5cm. With these dimensions in mind, this is what you need.

  • 3 wide wooden planks: 14.5cm x 90cm for the frame
  • 2 wide wooden planks: 14.5cm x 70cm for the frame
  • 2 angled wooden planks: 14.5cm x 70cm cut diagonal for frame
  • Thin wooden planks (2cm x 2cm) for the lid: 3 x 70cm, 2 x 90cm
  • Corrugated plastic sheet for the lid – the only material I had to buy. Approximately  95cm x 75cm.
    (An old window would work too, but it adds weight)
  • For the bottom 70cm x 90cm: A sturdy rug attached by sandwiching it between thin wood strips
    (This worked for me because I used trays. Without trays, I don’t recommend this—the water will soak the rug). Wood planks will work great for this as well.
  • A few screws and two hinges for the lid.
  • Handsaw and screwdriver
Main frame seed starter box from scrap wood

The idea was to create a little protected space that stays warm but allows airflow. For your own comfort, it’s helpful to place the box on something like an old table. If you have limited space or sun exposure, wheels can be useful.

I keep the box in a sunny corner of the garden, and it’s been working surprisingly well. It’s easy to move and keeps everything tidy and contained. Just a heads-up: in summer, seedlings can burn easily. I prevent that by ensuring airflow and covering the lid with a light cloth for shade.

The best part? It cost me almost nothing—just a bit of time.

DIY seed starter box made from scrap wood