Sorry but you can't replace T12 bulbs with T8. The ballast is different. You can change the ballast but only if you know how.

I'd suggest you get a new fixture that takes T8 daylight bulbs. They have full spectrum light and that's what I use with great success. You need one with reflectors on the sides so the light is reflected downward. You can get both at Walmart for less than $50 or hunt up some garage sales. It says on the fixture which bulbs it takes.

Full spectrum means it contains all the colors of light and will have the light colors a plant needs to grow. Look at a rainbow and you'll see all the colors of light. It is the one that most mimics sunlight. IF you want to know exactly google it.

There are some lights that are made for growing plants but they are expensive and I don't think they give better results.

Lumens is the amount of light a fixture gives off.

I don't think you need to be concerned about any of this except to get a fixture that takes T8 bulbs and get T8 daylight bulbs.

Tell your dad that your fluorescent light will use less electricity than a standard bulb in a single bulb lamp and less electricity than that old fixture with T12 bulbs

So T12 bulbs would not be adequate for the seedlings? I don't think dad would buy a new fixture unless it was really cheap.

If you already have T12 fixtures then by all means use them. If you decide to buy more or just want to upgrade then buy T8 fixtures or better...Jack

T12 aren't the best but they will work if you can find them. Many of us used them for years before the T8 and T5 were available.

The problem is they just don't put out nearly so much light, and use more electricity, and the bulbs have to be replaced each year for best results. So you really need to have more than 1 fixture when using T12. See if you can find another old used fixture from a friend or maybe on craigslist.

Then buy the best bulbs you can find with the highest lumen ratings on them (lumens labeled right on the package).

Another option you might want to look into is called Wintersowing. It has its own forum here with all the info on how to do it. Just click on its blue FAQ button to begin. It is done outdoors and no lights required for it.

Dave

Here is a link that might be useful: Winter Sowing forum

Which is more important: more lumens or full spectrum?

For growing seedlings only - more lumens. Full spectrum is only required to force blooming - which isn't usually a goal with seedlings.

Dave

Any bulb will do for seedlings. From years of experience just keep your seedlings close to to the light to prevent legging. you can drape aluminum foil over the sides to hold the heat and reflect more light back to the seedlings. This is s good trick. Dont waste your money on grow bulbs they are no better ,just cost more. This info is just for starting seeds of course. No. 12's are fine.

Thank you guys, I'm glad to hear the T12s will work. We actually do have a second fixture so I can set that up too, we just have to head out and buy new bulbs, the ones in there now are pretty old.

Thank you guys, I'm glad to hear the T12s will work. We actually do have a second fixture so I can set that up too, we just have to head out and buy new bulbs, the ones in there now are pretty old.