When Should The Light be Changed?

A customer has a question and I hope we can get some opinions on it, thanks.

“Question about changing from 18 hr day light to 12 hr day light, and length of grow cycle. Say the plant is listed on your site as 76 day flowering period, and height is listed as 23”-76" When should the light be changed from veg to flower? Indoors HPS/NMH lights available. Also, with a 76 day flowering period, what is an average grow cycle, from germinating to harvest in days?"

1 Like

It would depend on how tall you want your plants. Those heights and flower times are averages so it is ultimately up to your grow setup and methods. I would figure at least 4 weeks Veg time with a photo seed if not more and then tack on the 76 days of flowering would give you a ballpark around 106 days from start to finish. This all depends on your grow setup and what you are using for lights. I usually add a couple extra weeks to the flowering time they have listed. But again it would depend on how tall you want your plants to finish.

Atleast 7-8 weeks veg time other wise good advise


I vegged for about 6-7 weeks. Keep in mind the flowering time is an estimate and, at least for me, took at least 2-3 weeks longer than I expected.

I know that wasn’t your question but wanted to point it out since you seem to have done your homework and looked at plant details pretty closely.

Good luck!


I veg for at least 6-8 weeks. It makes for a nice healthy plant that is sturdy and yields a nice amount!