Introduction: Make Cheaper LED Growlights

I live in Seattle. I love gardening, but the grow season is pretty short here, relatively. We start most plants from seed inside during a time when a lack of light makes seedlings, especially cilantro, too leggy to stand. When I started gardening here, I was shocked, and still am, at how expensive LED grow lights can be.

Turns out, you can buy the components you need very cheaply to convert fluorescent lights with ballasts to lights that can run LED tube bulbs you get online. You can hang these light strips however you like, but I find that cutting two wooden blocks so that the bulbs sit inches above the seedling germination trays work best for how I start my vegetables.

Everything you need, save the bi-pin connectors, is already in the light itself. All existing wire is re-usable with the new connectors. For me, as I like using the full-spectrum bulbs, I've found I can cut my costs by 60% when I convert the lights from ballast-powered to AC myself, rather than buying LED-ready lights.

LED Bulbs are only powered from one end, whereas the fluorescent bulbs need a wire connected to either end of the bulb. This instructable will help you remove the power from both existing lamp holders and use the existing wire to install a new set of powered lamp holders on one end and use a pair of old lamp holders on the distant end.


T8 Fluorescent Light (Preferably Used)

Medium Bi-Pin Fluorescent Lamp Holders (2 pack)

Wire Strippers

Phillips Screwdriver

Wire Connectors (2)

Step 1: Remove Old Bulbs and Cover

SAFETY FIRST -- Always perform electrical work with the light unplugged!

These instructions are for 2-bulb fluorescent lights. If converting a single-bulb light, the process is basically the same, you just need a single new bi-pin lamp holders.

There are typically two Phillips screws that hold the cover shield onto the light. After removing the bulbs, you will see one screw on each end of the light case. Remove those screws and set aside with the cover.

Step 2: Remove Ballast and Old Lamp Holders

Remove the screw, or two, that holds the ballast onto the light fixture. The wires will be bundled up. I find it helpful to straighten everything out so that it's easier to see at this stage.

You should see the following wires in the light.

  • One black wire and one white wire coming in from the plug and going into the ballast.
  • One blue/brown wire and one red wire coming out of the ballast

Cut all wires connecting to the ballast as close to the ballast as possible.

The old lamp holders slide into slots in the main light housing. Chances are, you pulled one or more of them out whenever you were removing the ballast. Slide all 4 of them out of their slots, clip the wires close to the base of the old lamp holders, as you'll need that wire later.

Step 3: Strip Wires and Install New Lamp Holders

LED bulb lights are only powered from one end of the bulb. For a dual-bulb light, you need to split each of the wires coming out of the power cord. You do this by reusing the old wire and butt splices to split the white and black power-supply wires. In the above pictures, what I've done is take the blue wire out of the ballast and cut it into two 1-foot lengths and use a butt splice to attach them to the black wire coming from the power cord. The same with the red wire. I cut it into two 1-foot lengths and used a butt splice to attach them to the white wire coming out of the power cord.

The fourth picture is one of the bi-pin powered lamp holders. There are two sets of connectors at the bottom of that lamp holder. The two on the left go to the left pin and the two on the right go to the right pin. It doesn't matter which wire you use (blue or red) on each side, but they must be connected to different sides.

Again, SAFETY FIRST! Make sure that you don't work on this thing while it's plugged in and do not connect both wires to the same side. This will cause a short circuit.

The fifth picture shows the blue and red wires installed into the new power-supplying lamp holders. You simply slide them into the slots in the light frame. Take two of the old lamp holders, clip the wires as closely as possible, and slide them into the other end of the light frame. This set won't have any functionality any more other than to hold the bulbs.

Step 4: Install Shield, New Bulbs, and Enjoy!

Use the two Phillips screws to secure the reflector shield back onto the light housing. The LED bulbs will have a sticker on them that indicates the powered end of the bulb. This end goes into the newly installed/wired lamp holders. Put the new bulbs in place, give them a 90-degree turn to lock them in place, and you're good to go.

You can install these in your growing area of choice, but I end up putting my seed trays on the floor by the stairs and balancing the light on two wooden blocks so that the light bulbs rest inches above the seedlings. This way, I can change the height of the light from the top of the growing plants by changing the height of the wooden blocks.

Best of luck to all who try this method. It's a really good way to eliminate the frustrations that prevent success in starting a garden from seed. Lights make all the difference in the world and I'm glad to share a way to make them yourself!

Indoor Plants Challenge

Participated in the
Indoor Plants Challenge