Grow Light Duration Calculator

Daily Grow Light Duration Calculator

Select a plant

IMPORTANT: This calculator is inspired by the comprehensive scientifically researched guide on optimal grow light schedules. If you want to dig deeper, I recommend reading this guide.

What Is a Grow Light Duration Calculator?

Have your indoor vegetable seedlings seemed a bit stunted and yellowed lately?

Perhaps your flowering orchids or African violets aren’t producing many blooms recently either?

I know it can be so frustrating when our precious plant babies aren’t thriving, especially if we’re new to indoor gardening and aren’t sure what the culprit is.

But often, one key factor in lacklustre plant health and growth boils down to improper lighting. Specifically, not providing the ideal daily duration under grow lights that each unique variety needs.

That’s exactly why I built this handy grow light duration calculator for indoor gardeners like us!

It takes away all the guesswork on how long you should run grow lights per day.

Now you can enter details on what you’re growing, and it will instantly recommend the ideal daily schedules for vegetative vs flowering/fruiting stages.

How To Calculate Grow Light Duration

This calculator is very easy to use. Here’s a quick 4-step walkthrough:

1. Choose your plant

Start by opening the dropdown menu and selecting the variety you want lighting guidance for.

Common houseplants, herbs, fruits, and vegetables raised indoors have preset options to choose from.

2. Note if they’re in vegetative or flowering stages

The calculator will provide tailored results for seedlings and mature plants.

For example, young tomato plants need more hours of light per day to fuel rapid vegetative growth.

But once they begin flowering and fruiting, the duration can be dialed back a bit.

3. Tap calculate

Go ahead and hit that button after picking your plant!

The calculator will crunch the numbers, analyzing the unique lighting needs.

4. Read the optimal daily duration results

A nicely formatted table will then display, showing two rows:

  • Recommended hours for the vegetative stage.
  • Recommended hours for flowering/fruiting stage

Following these exact durations for your LED grow light’s on/off cycling is key.

So rather than sticking to some generic fruiting plants that require “12 to 16 hours” guidance, you can now get tailored times.

Dhruvir Zala

Meet your guide
Dhruvir Zala

I’m the guy behind Farmingram, where I nerd out on all things indoor agriculture. Through rigorous research, my goal is to get more people excited about where agriculture is headed.