Why Change Wattage On Lighting For Flowering?

[Irish063]

Hi everyone,
This maybe a total noob question but I didn't seem to find a good answer searching or a quick search on Google.
I've noticed reading through various posts on here that people will switch to a higher wattage light during flowering. Is this because the photo period is shorter and thus the plants are not getting the same intensity/amount of light? My assumption is they are trying to get as much photosynthesis and stimulation to the plant to happen during their lights cycle?

This is my first grow and my plants are not near as tall as I was hoping. I'm growing in a 6'x8' greenhouse. Soil (that is probably not the best mix), roots organic nutes( they've only been on nutes about a little over a month). Smart pot containers and they have a supplemental 300watt mars hydro LED light. I have just switched them to flowering and am putting a heater in tonight since our night temps are getting to cold here in CO.

Any thoughts or suggestions are grateful. Here is a pic. I'll get a close up in a little bit. The tallest is about 2 ft tall

 

[Paul Simon]

Think about the amount of energy the plant is using during it's generative cycle(bloom). It clearly takes magnitudes more light energy to produce flower, resins and VACs than it does to just produce the leaf, stem and root material alone. The best performance usually comes from an initial 50% increases in PAR delivery from veg to bloom, then adding 10% of the original power value for 4-5 weaks to hit peak productions, then back down to finish.

 

[Paul Simon]

Also, as much light as possible is by no means good. It truly varies how much light intensity plants can handle based on genetics. Cookies nearly blooms in total darkness and HATES DE fixtures, but startfigher damn near needs to be a foot from a Gavita to really be happy.

 

[Irish063]

Haha.
Thanks. Good points. I figured it was something along those lines but wasn't entirely sure. I was thinking about it from the Suns energy perspective which I guess even in late summer into fall is still a lot more than a light fixture.
Unfortunately I don't know the exact geno's of what I have. I got these clones from an aquintance. Judging by there charateristics most of them seem Sativa dominant while about 5 of them are more indicate dominant

 

[DrMcSkunkins]

Hay...
Are those from seed?

 

[Irish063]

No, they were clones. I got them around 4-6 inches from an aquantiance so I don't know exactly what I have. They are about 3 months old from when I got them.
I want to try growing from seeds on my next go round. This way I know what the characteristics of the plant should be though out its life cycle. As well as have plants that are better suited for this climate

 

[Irish063]

I was thinking of adding another light inside. Possibly a 600 watt hps. Would a hanging version or one with a hood be better?
From what I gather hanging lights are good for veg to help promote literal growth. Is that correct?

 

[Irish063]

I wanted to add the light for flowering.