Mike,

It depends on what "small tropical seedling trees" your are growing. From mu understanding, they most of them require lots of light but not that much heat. But if your goal is to only get them large enough to put outside next year, you may have enough light. If you can lower the lights and still cover the plants, it will help.

Another Mike

I have the light on them so they receive the best exposure possible (2-4inches above the top of plants). Like I said these trees are seedlings and I'm growing them as Bonsai trees so there not nor am I trying to grow them very large. I was just asking because I was unsure if the 40 watts with 6280 degree Kelvin color temperature was enough power because i know that color spectrum is very important.

Mike,

Get a light meter. If the plants aren't getting 2,000 foot candles at their canopy, they probably are not getting enough light.

Mike