Grow Q&A: What’s The Best Lighting Schedule For Auto-flowering Pot Plants?

High! I’m a lifelong subscriber and lifelong reader of HIGH TIMES so great job guys and girls! Here's my question: recently I was blessed with acquiring some White Widow auto-flowering seeds. I've been a long-time cultivator but have never had an opportunity to grow any auto-flowering strains. I’m very excited to see these beautiful ladies mature and they are very short stocky bushy plants and only ten-inches tall at the moment.

I've got them under 24-hour lighting at this time and my thought is that being at 24 hours of light will make them produce the largest yield but with my inexperience with the auto-flowering strains I didn't know if this is even possible. So is it possible to keep an auto-flowering strain under 24-hours of light or do you need to take away the lights in order to stimulate the flowering cycle what would you suggest as a dark period for these type of strains. – Tom M.

Dear Tom,
I don’t recommend using a 24 per day light regimen for auto-flowering plants (or for any cannabis plants, for that matter). Plants need at least a few hours of darkness to process the light and water they take in during daylight hours. This is when they actually grow. I recommend an 18 hour on/6 hour off lighting schedule for areas where heat  and electrical costs can be an issue and 20 hours on/4 hours off if heat and costs aren’t a problem. Either way, don’t change the lighting schedule once you’ve decided on one.

Have a grow question? Ask away at

(photo of Critical + Auto courtesy of Dinafem Seeds)

1 comment
  1. Matanuska TF was supposedly grown in the 24 hr sun periods… the ruderalis “auto” strain thrives in constant light in nature but it doesnt do as well in a grow room?

Leave a Reply

Your email address will not be published. Required fields are marked *

Related Posts
Read More

Growing for Terpenes

Increasing terpene production can result in a more flavorful, enjoyable smoke.
Read More

Chadivation or Cultivation?

The cult of great cannabis and why legacy cultivators will always produce better weed than big business.
Read More

Predictive Plant Analysis

Developers at Texas A&M University and Mariposa Technology tackle THC levels and plant sexing.