Depends on which herbs. Depends how many plants.

Herbs are dill, savory, basil, oregano and sage, 20 plants total, approximately 4 of each. Small setup, in 2 twelve inch in length jiffy pots holding 10 seedlings each, I have them about 3-4 inches from the light.

This is what I'm trying to find out also. If this helps I'll relate what I've experienced in the last few weeks. I had spearmint under a single 15 watt plant and aquarium light and it lived, but unhappily. It got leggy, but seemed to have enough light to grow without dying off. I've since switched to 2 15 watt bulbs, but it's too soon to see results. If my spearmint can live under one I hope it can thrive under 2 (slow growth is acceptable to me).

With that in mind I'm optimistic about your set up. Your initially 10 watts higher than where I started and you have a good variety. Also it should be noted that plants coming from seed (mine were bought already half grown) can adapt better to varied light conditions. A plant grown in full sun develops tough leaves to prevent sunburn and when it's brought in those tough leaves can't absorb light readily enough. Grown from seed it can adapt to the light.

Most herbs, including all the ones you list, develop their best flavour from a combination of intense sunlight and well drained soil. You should provide the absolute maximum fluorescent light you can cram in, it will never be too much. It sounds like you have the maxiumum light you can get with your current setup, it will probably be adequate while the plants are small, but I think less successful when they get past 4-6" tall. Also, without strong UV they will probably not have quite the same flavour as those grown in the sun.

To increase the light levels, think about switching from straight tubes to compact fluorescents. You could perhaps get four 23W spirals over your plants, giving a more intense light suitable for taller plants. Also, there are so-called "power compacts", one suitable for your setup would be a twin-tube 55W. That would provide a little less light than 4x23W spiral compact fluorescents, although more evenly distributed and from a lot less electricity. You could possibly even use two of them when the plants get really tall.

Thanks shrubs and mkiker, appreciate greatly your input. I am going to add two more 20 watt fixtures, and if they get leggy, two more! Shrubs, this is a makeshift setup I have going, with the plants inside an open 20 gal aquarium with the straight tubes balanced on either edge, so I don't think a spiral would work, but I will definitely keep it in mind if in future I opt for a more traditional "under lights" arrangement. Mkiker, I did not know that leaves developed a certain toughness when outdoors, this is interesting. Hopefully, your point about mine being grown from seed will prove true. Thanks again.

Eileen

You might also try to move the plants closer to the lights, if possible. Many herbs need to be within an inch of fluorescent tubes or they start to get leggy. Keep them trimmed to a few inches tall or you'll lose the lower leaves anyway. Perennial herbs like thyme and mint need a period of winter cold dormancy or they'll die after a year or so, so start fresh seed every six months or so for a continual supply indoors.

nygardener, thanks for the tip...I have them approximately 1-2 inches from the light. The basil, savory and oregano are already germinating!! Thanks lots.

Eileen

so was the extra light added without sacrificing what the old narrower grow bulbs could do? More light without loosing the best spectrum is good, more light as a compromise is bad. If the former then you'd be crazy to spend more on grow bulbs when a PA is good enough at half the price (or better as some websites claim since the plant gets a wider spectrum and there is debate over how they handle that).

Posted the above in the wrong thread, sorry about that