When to reduce the 18-hour grow period

My plants are going on 3 weeks under 18 hours of light. How long do I leave them on 18 hours?


@Bobtcheck welcome to the forum. This all depends on the size of your grow space and how many plants you are growing.

If you have a short grow space and not a lot of room you can flip your lights to 12/12 as soon as the plants are healthy in veg.

If you have a larger grow space and have some more room to work with I’d let them veg longer. 6 to 8 weeks is my preference so you can get nice healthy bushy plants before flipping to flower. You get a better yield that way as well.


Thank you MDBuds. Shortly after starting veg I put a 1000w metal halide veg grow bulb on top of the 7 California Orange x Skunk and 4 Gelato plants that germinated from seeds I got from Homegrown. I want to initiate flowering cycle but don’t have lights in the spectrum anywhere near as powerful as the 1000w now. Can you tell me how strong of light’s I need to finish out the grow? I want to get away from the 1000w.

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@Bobtcheck you need a light capable of at least 700 ppfd to flower successfully with decent yield. The size of the light and the wattage needed to cover your grow space all depends on the size of your space. If you can tell me the size of your growspace I can suggest a few lights that will do the job.

I do not know your lamp but bulbs run from $30-$120
here is an ebay offer, they only have the 1000w
Amazon - https://www.amazon.com/dp/B07R6Z4HRX/ref=sspa_dk_hqp_detail_aax_0?psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyUkZJNjlLRTUxRFE4JmVuY3J5cHRlZElkPUEwOTM4Mjc1MVgwUzYyVzc0S08xUSZlbmNyeXB0ZWRBZElkPUEwMjc1NjkyMkJTT0hTSkkwRzFDUyZ3aWRnZXROYW1lPXNwX2hxcF9zaGFyZWQmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl

I’m using my bedroom, along one wall, currently 3’×7’ plants are not touching each other yet. Nothing fancy not even mylar. Have to keep fans going when light is on, I’m not venting outside… Have 11 plants all germinated and planted same time, incredible the variance in size. Don’t know what to do with small plants when switch to flower. 7 California Orange×Skunk, 4 Gelato. Don’t know how they grow so am hoping for a lot of advice. I got real sick when this project began didn’t keep good records from hosp. I think they are 6 to 7 wks. Trying to send pics. Thank you all very much.

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@Bobtcheck with that grow space I would suggest a light from Mars Hydro’s sp line. They’re made for 2x4 and 3x5 tents etc… I think the sp 3000 would work for you or something similar.

As far as how they grow I haven’t grown Ca orange skunk yet or the HCC Gelato. But, as far as keeping the canopy even, you can always raise the pots of the shorter plants by placing things under them like blocks of wood or other pots etc… so the entire canopy gets the same light.