Inexpensive Seed Starter




About: A creative engineer, who builds because I cant bring myself to have someone else do things I can. I had a great maker childhood, one crazy uncle who built his house from materials he got off his land and was...

Over the past few years the family has started seeds for our garden. We have tried a few different enclosures from store bought, to floating the starting tray in our fish tank. (it works if you don't sink the tray with the filter)  The biggest hurdles were light and temperature. Our house has a programmable thermostat and in front of the door wall is the sunniest but not the warmest.

So last year after killing off the first set of seeds, I made a seed starting box, with lights, air flow, and heat (from the lights). The plants thrived.

Here is how its made...

Step 1: Materials

1 Sterlite clear plastic container.
3 temporary bulb holders (home depot rubber coated) UPC # 0 78477 83939 1
3 CFL 13w light bulbs (do not use other types the heat would create a dangerous situation)
2 wire nuts
1 cord end (I got this one off a dead microwave) a short extension cord work well also
3 band ties
emergency blanket
double sided tape
piece of bubble wrap the size of the bottom of the container

hole saw (the size of the bulb holders) 1 1/2"
Wire strippers

Step 2: Drill Light Holder Holes

Lets get started

A few words of caution:

If you are not comfortable with electrical wiring, please consult an electrician. You use this instructable at your own risk. Wiring lights is not difficult however if done wrong can be dangerous. Using standard incandescent / or halogen light bulbs will over heat the starter and could be dangerous

Chuck in your hole saw (1 1/2") in the drill and drill 3 holes in the lid of the bin. The holes have to be close enough together that the wire ends of the sockets touch with enough slack to connect the cord.

Step 3: Install the Lights and Wire

Once the holes are drilled you can install the light holders socket facing the inside (photo 1) and place a band tie around the light to stop it from falling back in the hole (photo 2)

(Legal notice : IF you take on this project you do so at your own risk. Exposed wire can cause injury. IF you are not comfortable with electrical wiring please consult an electrician. Do not put tension on the electrical cord as wire nuts are not designed to take a strain load)

(Photo 3) Wire, use red wire nuts  to wire all the white together, then wire all the black together. Since the holders don't have a ground it will just hang free.

Wrapping these connections with electrical tape will give a bit of added protection if a nut comes loose or a wire is exposed.

Step 4: Wiring Explained

Well at least for this project..

There are notes on each picture.

Cut off the female end of the cord.
Strip back the insulation 6". This will reveal 3 wires (assuming you used a cord with a ground) black, white, and green.
Strip back 1" of insulation from the black and white wires for the cord.
Strip back 1" of insulation from the temporary bulb holder black and white wires.
Twist all the black together.
Twist all the white together.
Trim back the copper wire to 1/2 to 3/4".
Twist on a wire nut clockwise to each set of wire.

Step 5: Line the Bin

Adding reflective foil to the bin helps the plants use all the light produced by the bulbs and light up your house at night. Cut a strip of foil the height of the bin and wrap it inside and cut to length.

Keep the foil in place by using double sided tape between the foil and the bin.

Cut a piece of bubble wrap the size of the bottom and place bumpy side up. This will provide a drain if you over water and insulate against a cold floor.

Step 6: Punch 4 Vent Holes in the Bin

To keep airflow I added 4 holes in the bottom of the bin. 2 at the bottom of each end. This allowed me to control the amount of heat the bin retained. Crack the top and the heat rising out of the bin crates a vacuum pulling fresh air in the bottom.

Use the same hole saw used on the lid for the lights, leave the reflective material in place and cut slits up either side to create a flap. You can close the flap if you want more or less airflow.

Step 7: Add Light Bulbs and Pots

I used 60 watt florescent bulbs. It seemed to give enough light and not cook the plants. When the plants got large I raised the lid with yoga blocks and added larger bulbs.

I close the lid until the plant got around 2 inches tall. Keep an eye on the moisture. They need to stay damp when sprouting, If they are too wet when growing they may form mold. Use starter soil and clean all your pots from last year.

This project should be plugged into a GFI protected circuit.

Enjoy your garden, and good luck.



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    50 Discussions

    Cool! I'm trying this! Right now there's 6' - 8' of snow outside -I'm thinking growing season is going to be a bit delayed this year :D


    4 years ago

    Very cool!

    Rather than use foil to reflect light I have read that flat white paint actually reflects more light. I use sticks to anything , as listed on label , and it works fine . Spray for plastic if you can get it in flat would make short work. Foil may be quick and cheapest.. Look for lights in daylight range up in 5700-6500 K temp range(blue) as listed on package.


    6 years ago on Introduction

    From What I have read the lumens are about the same, it is the wave length that makes a difference between florescent and incandescent for plants. Anyway why so many nit pickers on this pretty straight forward project?

    2 replies
    Foaly the Centaur

    Reply 6 years ago on Introduction

    No, i thing it's a perfectly valid concern. It is updated now, but many people don't know that much about electronics. They might just use masking tape and possibly start a fire, as well as weakening the connection.


    6 years ago on Introduction

    Why not cover the bottom side of the lid with aluminum foil? The blue plastic is not going to reflect much light.

    I would be worried about the very delicate CFL bulbs breaking. Then when one does your seedlings will be contaminated with mercury and you will have to dispose everything. Instead, why not use strings of LED lights (sometimes called Rope Lights). Or strings of white LED lights sold at Christmas time. Yes, a LED puts out less light, but I wonder if the total quantity of the LED lights will add up to be enough illumination. Also they are not as hot so cooling is less of an issue.

    This past winter I I put a heating pad under my large tub. I did not have any cooling holes. An inexpensive thermometer I had inside indicated a temperature over 85*F.

    Atop the very warm tub I placed several clear $1.25 Home Depot "shoebox" containers that held my small starter pots. Inside the temperature of them was 75*F.

    1 reply

    Reply 6 years ago on Introduction

    Good idea on the double tubs. I thought about the foil, I just didn't want any conductive material on the lid.

    My starter 2 years ago was an off the shelf small dome that I floated on the top of my fish tank and lifted the light. The water heater kept the tank at 75 and the added moisture keep watering down. Worked great till it migrated under the filter spillway...


    6 years ago on Step 3

    You wrote, "Wrapping these connections with tape will give a bit of added protection".

    You should have said, "electrical tape" to prevent someone from using celophane (Scotch) tape, duct tape, masking tape, whatever.

    1 reply

    6 years ago on Step 4

    In the u.k Brown is Live, blue is Neutral and green/yellow is Earth.

    1 reply

    Reply 6 years ago on Introduction

    Didn't know that, I think I will add it to the instructable. Thanks for the info.


    6 years ago on Introduction

    Another word for 'seed starter' could be 'germinating station', but this is great! Definitely gonna string one up! Thanks :)

    3 replies

    Reply 6 years ago on Introduction

    I am not sure if I can add "germinating station" to the key words without republishing, but would like too.


    6 years ago on Step 4

    Marr nuts are great for a static connection, ie; in a wall or ceiling, since your application involves a lot of movement, I'd recommend backing the Marr nuts off after the initial connection and melting some solder through the threads, then reinstall. I'd further secure with electrical tape. Call me paranoid about electricity.


    6 years ago on Step 7

    You wrote, "Use starter soil and clean all your pots from last year."

    You should have said to clean with diluted bleach.