Hello, this forum is great. Tons of great info here. I have a question. I have set up a closet grow op with a 400W HPS and am planning on putting 4 plants I have started under a fluorescent light which are just about ready to be transplanted to ~3 gal. pots and throw into the closet. One thing I'm curious about is I have read a lot that 24h on/ 0h off is best to use while others say 18/6.. Now, is there any disadvantage to using say 20/4, or 22/2? Also, I'm a little worried about heat.. I'm thinking putting a few smaller fans in there for circulation, and a larger fan for exhaust... possible a couple PC fans and some ductwork if necessary.. Does anyone know if a 400W HPS in a ~2' x 6' is going to create too much heat.. I'm pretty confident on my setup, but any suggestions or other options or tips would be greatly appreciated. Thanks in advance. And thanks for providing all this amazing information.
Its up to you. Im sure through reading you have learned the pro's and con's according to whomever. Its hard to sort it all out sometimes, so I say to go with what sounds best to you. I started under fluro's 24/0, til I put them under a screen, then it was 600w MH 18/6.... til flower, then HPS 12/12. Take natures advice.... your the sun now. I would go with 18/6, although I do not think there would be any real difference between any of those cycles during veg... Im sure others would disagree. I hope that is somewhat helpful.
A lot happens, inside the plants, during the dark period. I use 18/6. Dark periods are important to the plants, they actually grow quite a bit with the lights off. But it doesn't hurt to experiment, for what's best for you, too.
I think the 400w HPS is good for your space, but you'll definitely want to monitor the heat. I use a thermostat that my fan's attached to, and it will kick on, to maintain a specified temperature. I think a 250w setup is pretty common in a 2x2, but I'm about to cram a 1000w into a 3x3... As long as you manage the heat, you'll be fine.
Plants stretch the most during the dark period. They grow in height but not so much in budsites. In addition to the stems, roots also grow fastest at night. Having no dark period helps to keep container size down. Myself, I only give plants a dark period when they're either flowering or rooting. Having a very short dark period isn't helpful to the plant. Just like people falling to sleep, plants need time to change from day mode to night mode and back again. There needs to be sufficient downtime before switching back or all that's accomplished is a waste of energy. If you personally need the lights off a couple hours per day, then it won't actually hurt the plant.
Thanks for the info guys. Another question I have: I currently have my plants under a smaller fluorescent lamp that I used to start them. They have just gotten their second set of leaves, and are at about 3" currently. The question I have is, is it a big shock to the plants to switch them directly from fluorescent, to the 400W HPS, and when should I transplant them from the cups, to normal (~1.5-3 gal.) pots.
As long as it's set up right, switching to a 400w HPS would be a relief to the plants, not a stress. Seedlings stay in little plastic cups of a seed-starter substrate until the 3-bladed leaves first appear; when the single bladed leaves are fully grown. From then on, they start needing nutrients to stay healthy. They get transplanted into pots big enough to complete vegging in, full of nutritious vegging soil. A good vegging soil mix can support the plants for six weeks without more ferts needing to be added.
I put a 600w in a 2x4 closet without big heat issues, but i have lots of ventilation. Jellyman is right, those babies should thrive in the new light!
We bought an oven hood vent and set it up with some duct work and the exhaust on it is simply amazing.. Not like my current hood vent. Also, didn't have to cut any holes in the wall/door. Now we're just going to put in some intake, and repot the plants and should be ready to get these babies in their new home. Here's a couple pictures (with a matchbook for scale) to show you guys what I have going on: (Click for larger view) The pictures kinda make them look small, but they've been growing for a few weeks now. They had a spurt, and now are kinda chilling where they are. I'm kinda worried about them getting "root-bound", and the smaller fluorescent light that they're under, which makes me think that they're good to go. so I want to get them into bigger pots, and into their new home under the HPS. Thanks for your info. Personally, I think they should be ready to be transplanted.
I put them into bigger pots, and under the 400W HPS last night, the room temp is ok, but the humidity is at 20. That needs to go up, a few of the plants are wilting, im hoping that is just a lil shock from the transplant. Also my light is about 2 feet from plants. Any thoughts on any of this??? Another thing im considering is changing the way the bulb sits from horizontal to vert. seems like i am wasting a lot of light with the top half of the bulb being so close to the hood. Anyway, some thoughts and advise would be great!! Thanks all! EDIT: Here's some pictures of the setup: Note: 24h since transplant. Light Makes the camera on my Blackberry go kinda wonky, so bear with the quality of pics. Also, as mentioned this is using a (~) 2x4' closet with upper shelf removed & a 400W HPS & stove hood vent setup for light/exhaust and fans for circulation. Going to add an intake fan asap as well. --- Date/time & Temp/Humidity Note: Click to enlarge - Landscape shot of the setup from the right end. - Landscape shot of the hood vent/duct work. This made it unnecessary to drill/cut any holes in the wall/door with use of a 2ply cardboard "shield" to block the space between the door. Will be upgrading this asap. - Another pic of the left side/door of the setup & hood vent. - Better shot of the hood vent/ductwork used for housing the light, and helping with heat. It exhausts outside the closet, and is keeping it at a steady 25C /w the door closed @ 24/0 - A shot of the underside of the hood vent & light. As mentioned, my camera phone doesn't like the light I suppose. - Pic of the right end of the closet. Not much going on over there... yet. - Another pic of the right end. - Left end of the closet. Another fan & extra space. - Pic of one of the plants 24h after transplant with a bottle for scale. - Shot of 3 of the girls 24h after transplant. - Another shot of the plants - Pic of the "transformer" I'm using /w the light.
i believe id have left them under the cfl's till they were at least 5 inches tall,,,, but i do lst on my plants,, and grow 100% under flouro tubes using a scrog, but ive had a 400 in the past,,,and even then i did a long vegg under the flouro's and then threw them under the 400,, and your space i believe is going to get very hot,
As mentioned, it stays at 25C in there (~ 2' x 4' @ 24h/0h) with the door closed. Our hood-vent exhaust design works wonders. Two people said that it would be a "relief" to put them under the 400W (it's actually 430W), and I didn't get any response, so I went ahead with it. In any event, like most people say, it's "weed", and is quite versatile. They're doing great either way. Thank you very much for the input though. Do you have any thought on humidity? My temp/humid digital guage (from home hardware) keeps giving a warning of 20% humidity, and it won't go up.. I tried putting a container of water in there to evaporate and create some extra humidity.. Any thoughts?
i create humidity in my tobaccoo kiln with a crock-pot,,, just fill it with water set it on med or low,, and let it go,, it will of course create a little heat,,,but you got a 400,,, a crock-pot's heat is no worries,, it will solve your humidity level,,,, just experiment with the temp settings,, and the placement of the lid,,> all the way off,,,,a gap in it,, but never all the way closed, good luck, and let me know how it goes 4 -u
Hey, That hood design sounds thrifty cool. Also I heard that sending photos with your phone is not safe. Idk Happy growing Url
Good advice given here. Your plants were too small to transplant and they were shocked by the move. Plants should have 3-4 sets of leaves before transplanting and the roots should fill the soil ball to the sides and bottom of the pot at transplant time. Way too soon, but they will eventually start growing normally in a few days. PW