I have never used spiral, spot, or flood Gro-lights but I just hung two, 4' shop lights above the top shelf of one side of my orchid greenhouse. I decided to use a pair of T8, 6,500K bulbs in each fixture for three reasons. Number one, I am using these fluorescent fixtures between 5:00 PM and 7:00 AM, since I have natural SE exposure light during the daytime hours. Secondly, these T8 light bulbs are available at big-box stores and I can get them in a 12-bulb pack. Lastly, these bulbs are a heck of a lot cheaper than the Gro-light bulbs.

Natural, north exposure light is around 10,000K. The higher the lumens and "brighter" the light, since there is a lot of blue spectrum light present. Cool-white bulbs generally are 1000-1500K and give off a lot of yellow sectrum.

I have three pics of the two newly hung shop lights, though my V. 'Sunlight Orange' gets in the way of the light fixture in pics 2 and 3. When I took the pics I did notice there is a new spike forming on the vanda. The final two pics are of the other side of my greenhouse, primarily my "baby" orchid side. There are approximately 150, 1 yr old orchid plants here. I could not get far enough away to show more than about a third of them. Next week I am going to hang two more shop lights above the baby orchids. I may go with 4-bulb fixtures rather than 2-bulb ones, but will probably stay with the T8's.

Click on each pic for full size. Ken