I've grown my vegetable seedlings under shop lights for many years with good results. This year, however, all of the tomatoes, peppers, and basil were very leggy - only the eggplants were normal.

All of the plants were grown in 3.5" plastic pots filled with a 50/50 mixture of MG Seed Starter and screened MG Moisture Control. They were germinated over heating pads (temps in the 80s), which were removed as soon as germination was complete, then kept in the cellar (temps in the 60s). The lights went on the moment the first seedling emerged and were constantly adjusted to keep them 1-2" above the plants. The lights were cycled 16 hrs on and 8 hours off with a timer, and a timed fan came on for three hours each day.

I only watered (from the bottom) when the top of the potting mix was quite dry, and fed them twice over the six weeks with dilute MG liquid fertilizer (8-7-6) at 1/3rd the recommended dilution for "feeding with every watering", i.e. 5 drops per quart. After six weeks the tomatoes were 14-16" tall and the peppers after 9 weeks were 12", all leggy in appearance. The sunlight during the hardening-off produced larger new leaves, but couldn't reverse the legginess.

The main change this year was the lights, which is why I suspect them. In the past I grew under four T-12 48" cool white bulbs and the plants were beautiful. About three years ago I switched to four T-8 3500K bulbs, same total lumens, and noticed they were a bit leggier but acceptable. This year I used new 5000K bulbs because I read the cooler light will make for stockier plants, but just the opposite happened. The bulbs are Phillips ALTO F32 T8/TL 850 with an electronic ballast designed for four T-8 bulbs.

I'm wondering if these triphosphor bulbs designed for human eyes produce too narrow band widths for optimum growth of tomatoes. Any ideas??

TomNJ