I really don't see a reason not to run them during the day. Supplemental light, the way you are using it, is to increase the total amount of light the plant receives; it is not to manipulate the length of the photoperiod. So you should be fine having them on during the day instead.

WHEN to run them was a question I did not ask myself before setting them up! So if the day is, like now in fall, 9 hours long, run them then? Dawn to dusk?

We'd need to know what you are growing as light requirements vary.

tj

Thanks.

In one room, mostly exotic coleus. Most large. Also Mahogany Hibiscus (tree / shrub), Pineapple Sage (ornamental, not culinary), Begonia “Whopper,” 2 dark leaved Colocasias (Black Coral and Illustris), Plectranthus Mona Lavender.

In a different room, a Meyer Lemon, a few Rosemary plants, some spider plants, a few impatiens, more exotic coleus, tradescantia zebrina, Begonia “Whopper”, Plectranthus Mona Lavender.

In the third room with a skylight and a small window : more coleus, geranium, more tradescantia, impatiens, Begonia “Whopper”; and houseplants like spotted angel wing begonias, crotons (those have gone all green since not enough light), jade plants.

Plants are placed in various rooms more due to size than anything else. The biggest ones are closest to the front door and have the biggest window; plus many of those are in ceramic pots I did not want to lug upstairs. I can do some rearranging by light needs. Subject to how heavy they are!

I have 2 - 4'x8' growing tables in the basement that are about chest-high.

Each table is built so it sags slightly toward the geometric center
and covered by a 4'x8' sheet of FRP panel (Fiberglas reinforced panel)
with a hole in the center through which any overflows or spills drain
into a bucked that rests on a 4'x8' storage shelf below the top.

The
image shows the T-12 fixtures with 1-1/2" 40W bulbs I first used after I
built the tables about 20 years ago. There are 11 fixtures with 2 bulbs each above each
table. The plants are grouped by ht and fixtures are hung at different heights so they almost tough the tallest part of the foliage mass. Several years ago, I changed over to T-8 bulbs with color
temperature 5100K. This fall, I bought all new LED fixtures for the
basement grow area and the garage. They provide 5200 lumens in color temperature 6000K. The old fixtures were 80 watts each, the new are 42
watts each. I run them 16 on: 8 off every day from the time I bring
plants in in late Sep/early Oct until they go back outdoors sometime
around Memorial day. They turn off at 11PM and come back on at 7AM.

Al