When to discontinue lighting on seedlings.

Question

I have gaillardia seedlings growing indoors under a lighting system. They now have the beginnings of their first true leaves. I have removed their overhead domes but am wondering when I should change their routine of 24 hours per day of overhead lighting and begin giving them 8 hours of darkness at night and 14-16 hours of supplemental light during the day. I would very much appreciate your advice.

Answer 1

Early plant growth will require 18- 24 hours of light. Many growers supply a 24 hour light cycle and many growers have great success with an 18 hour cycle. The optimal light cycle period is up for debate. My personal thoughts are that all living organisms need a time of rest. So I offer my seedlings a six hour period of darkness when the second set of leaves show after the true leaves.

Here are a couple of articles that can help:

https://www.gardeningknowhow.com/garden-how-to/propagation/seeds/do-seedling-plants-need-dark.htm

https://www.gardeningknowhow.com/garden-how-to/propagation/seeds/leggy-seedling.htm