Setting Up a Grow Light Timer (and Not Ruining Your Flip)
By The Budometry TeamPublished Updated
A timer is a $20 device that protects a three-month grow. It is also the piece of equipment people most often set up wrong.
Part of our pillar guide: Cannabis Grow Lights: Sizing, Height and Schedules
Digital over mechanical
Mechanical dial timers drift, have 15-minute minimum increments, and reset unpredictably after a power blip. A digital timer holds an exact schedule and usually keeps time through short outages on a backup battery.
A sane schedule
Set lights-on for the coolest part of your day if heat is a problem — running the light overnight and dark during the hottest afternoon hours can drop tent temps by several degrees at no cost.
After a power outage
Do not try to make up lost hours. Get the plant back onto its normal schedule at the next scheduled on-time and continue. One short irregular dark period is far less harmful than repeatedly shifting the cycle.
Frequently asked questions
- Should the fan be on the timer too?
- No. Keep exhaust and circulation fans running continuously, especially during lights-out when humidity climbs.
The full guide on this topic
Cannabis Grow Lights: Sizing, Height and Schedules
How to size an LED to your tent, set hanging height by stage, run 18/6 and 12/12 on a timer, and hit the PPFD and DLI numbers that actually grow flower.