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Your email address will not be published.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
Dry Farming
Read More

Dry Farming in Humboldt

A small region along the Eel River in Humboldt County allows cultivators to grow cannabis without ever watering their plants.
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.