How to calculate harvest time

I ask this because most seed banks state something such as 7-8 weeks flowering but that doesn't help me much in calculating harvest time because if they start counting from the first flowers that come out then one does not know precisely when will the first flowers appear.

So let's say you're growing a strain that says it is 7-8 weeks flowering time. The seedling pops out of the soil and you keep it it under 16/8 for 3 weeks.
Then you switch to 12/12, the plant will not immediately produce flowers, will it?

So once you have switched to 12/12 how long will it take on average for it to be ready to harvest?

I'm asking this because I'm taking a 10 day trip and need to calculate when to sow the seeds so that the plant can be cut before my trip.

Thanks.

After switching to 12/12 your average hybrid will take 63-70 days. It takes about a week to 10 days maybe a bit more to go from veg to flower. Depending on the cross it could go shorter or much longer. Even if they said 56 days flower it's usual gonna go 63.

LOL!

You can't!

So many things can effect the out come and it's basically different for everybody/grow....

It's FAR simpler to say this, "Most will run 1-2 weeks longer then any breeders report"..

Sow 3 weeks earlier then the breeders report!

Do you think it is particularly bad to sow on waning crescent moon?
I heard generally speaking that plants sowed on those days are born unhealthy.

avillax said:

Do you think it is particularly bad to sow on waning crescent moon?
I heard generally speaking that plants sowed on those days are born unhealthy.

Click to expand...

Hmmm,,,,,and a woolly caterpillar grossing the road means a long winter....Same for a Amish farmer taking in more hay then last year....Don't forget the Ground Hog!


No!

So then I would be perhaps risking too much of not having the plants ready for my trip, because if the trichomes are still young, maybe after a 10 day trip they could have turned very amber, right?

While every strain is different and every grow is different... i agree with phunt.

Once you flip the lights to 12/12 clones will generally take about 10 days to start showing buds. I have had some show in 6 days from flip. If you are going from seed, however, different story... if you flip before the plant is mature (about 6 to 8 weeks of veg) it can take up to 3 weeks for buds to start showing. I had that happen with NL5 a couple times. 4 wks veg then flip and was about 18 days before buds showed.

And... i agree with finish times... i have never flowered a hybrid longer that 75 days from flip to chop. Usually about 65 days though...

OK and what would be your advice on this:

I want to grow mainly Sativas under 1 x 300 watt Mars Hydro (actual draw: 180w)
I want to grow 4 of them.

What yield would be greater in the following 3 scenarios:

1) Growing the 4 of them under that light with 3 weeks vegetation then 12/12 and let them stretch and fight for light

2) 12/12 from seed so they will remain small and easier to be under the light's coverage

3) 3 weeks veg then switch to 12/12 and just cut them a lot to keep them shorter.

Please don't say "just buy a new light"

20 years ago the members of the original pot cultivation forum came up with the theory that we ended up calling the 40/60 Theory.

Once your plants are put into 12/12 flowering lighting, you observe the stretch of new growth, and measure when that spurt stops. That time period will be 40 percent of your total flowering time, so you can estimate when the true ripening time will be.

Just add another 60 percent. As an example, if your plants stop stretching on Day 28 of flowering, then they will be ripe around Day 70.

Good advice from rollitup!