Flowering of short-day plants (or technically long-night plants) like poinsettias or chrysanthemums will be affect by lights at night, but tomatoes are day-neutral plants, so you don't need to worry about light at night.

well thats good to hear. the black tarp was a bit of an eye sore.

so is it even needed to run a 12/12 light period? or could i keep it on 18/6 and still produce the same or more fruit?

i did switch to an HPS bulb.

kylle, I am not that experienced with tomatoes myself, but I think more light will be better for it. It might reach maturity sooner even though the day-neutral part of it means flowering (once mature) is not affect by night length.

My standard response:

Look outside your window. Nature does a great job of growing plants. How much sunlight do plants get a day in the fields where there is no buildings to provide shade?

Mike

Hi kylle,
14 hours on + 10 hours off & you won't miss out on any total fruit harvest weight

thanks, gringojay

Look out your window? When? Where?

January: We get 1.5 hours less light than the equator in Central Indiana.

July: We get nearly 3 hours more.

Also remember that when you look outside you are looking at sunlight. I don't care what any manufacturer might claim, I don't believe any artificial light can do what direct sunlight can do. So, when using nature as a guide, keep in mind you aren't using nature indoors. Necessary hours of light from a grow light might be different from necessary hours of artificial light. Most plants can do well with 6 hours of direct sunlight (the accepted definition of "full sun"). Not so with artificial light. Plus, not all artificial lights are equal.

Tomatoes are not photoperiodic in regard to flowering, but some research suggests that anything beyond 14 hours straight is wasted light and more than 18 hours can be detrimental. Some research does suggest that an interrupted dark period can also lead to lower productivity and chlorosis. Google it. Can't remember where I read it. I do recall the interruption being full light because the dark hours were reduced from 7 to 3.5 hours followed by the photoperiod (day hours). So, a small interruption may not have any effect. Some plants won't flower at all if a little interruption occurs. Tomatoes are not in that group. My outside tomatoes grow beautifully and sometimes receive light at night from my bedroom window. I'm satisfied with my yields.

Joe

Just to add some info, tomatoes are generally day neutral. a 12/12 light darkness ratio is alright. I don't see any problem with that especially if its outdoor. Indoor tomato plants, as long as your crop is not leggy and you have good leave color with think inter nodes on top, then it will yield a good crop. Most tomatoes are self pollinating however some are also has small percentage of cross pollinating. Hand pollination might help you be more successful getting fruit formation or in commercial greenhouses they use flowering hormones and bumble bees to do the pollination.

It might help.

All sounds good, thanks for the advice. I look forward to seeing how everything turns out!