I haven't been on the forum for a while, last year I was setting up an indoor grow and a "buddy" got pissed at me and told my landlord. Long story short, I'm just getting back at it on the other side of the island and this time, I'm saving a fortune with a greenhouse. There are a lot of great things about this set up, the structure is on a raised platform bordering a pond so rainwater leaches into the rocks under the structure creating a natural "swamp cooler" that I take advantage of. Being up off the ground aids in positive airflow and protects from pests and it's in just the right spot to take advantage of the solar path. My biggest concern is the high temp in the greenhouse when it's sunny, it gets as hot as 100 degrees by thermometer at eye level, ninety at the soil surface. The plants have LOVED it in veg but I'm being told that these temps will yield bad bud. This IS NOT an option. I have several controls, an inadequate ceiling exhaust (6" Vortex) I'm preparing to upgrade to a 10", fans pictured and a 4" blower bringing cool air in from under the building. Here are some example temps: 72 degrees under the building/88 degrees soil level/95 degrees eye level. 76 under/93 soil/102 eye level I also have venting at the floor and gable (see photos). Will these temps ruin my crop in flowering? What am I missing?
Another member on here has a greenhouse where he can roll the walls up and just have screen. Very cool. Way nicer and effective then fans alone. I asked him about it and he has it down. Flowering, you want cool temperatures but getting air flow will help. I found the thread, some of his ideas may be the right ones to help you out. Nice people on the thread too. http://forum.grasscity.com/outdoor-medical-marijuana-growing/1302696-new-house-plants.html
The wind shredded my plastic and I had to redo the roof, but the 2 opposite sides are still wide open with nothing. Through this experience I've learned that you just gotta open that fucker up. I made one of the roof panels open/close-able for venting, and have been intending to make roll up sides but just ain't got a 'round tuit yet. But I know now that's the way to go. (accidental discovery) Temps are looking a whole lot better now. I'd strongly advise you to open the sides for venting. Fans are nice to have, and still necessary, but not enough alone.
Roll up sides will be something I'll look at but I need to be able to close it up because it gets too cool here at night and I live in the middle of a rain forest where the RH can hang at 99% for days. The vast majority of people here grow in open air and produce more mold than good smoke. I upped my 6" Vortex to the 10" and finished closing in my night-veg room bringing the exhaust more inline with sound numbers so am going to see how it goes. I have a friend who grows sea-level in open air and says he hits 90 degrees daily and he has good success. I may also try a strain that does well in higher temps. Between ventilation and fans I'm moving A LOT of air so if I can keep it at 90 or less, I feel confident I'll be okay.
Yeah, high heat+high humidity=powdery mildew I have high temps in dry conditions in my greenhouses. I have seen beauftiful grows in 120 degree greenhouses. Just have to have good airflow and keep the well fed and watered
I'm controlling the humidity well in my greenhouse. In mid-day it gets up to 95 degrees in there and the humidity drops to around 50%. I just hit 4 weeks today and the weight is already fairly impressive, I think I'm going to be okay. On a side note, I'm a little concerned about a critter, they call it a Looper around here....a fly that lays an egg in the cola that hatches a worm that eats and shits your plant into the trash can. I was talking to a guy yesterday about it and when I said I can't spray BT for it because I'm half way through flower, he looked at me like I was crazy. How late into flower is too late to spray?
If you have room for some 50 gallon drums in the greenhouse, drums filled with water are a great temperature stabilizer. They will absorb some of the excess heat during the day, as the greenhouse will try to stabilize it's temperature by heating the water, and then in the evening when the temperature drops, the water will give off heat as it cools, raising the greenhouse ambient temperature.
I seem to have gotten control of the temps. I installed a 10" vortex and also completed the "garage", the night-time veg box containing two 600 watt lights that now comprises almost half of the greenhouse space. The addition of this structure has in effect decreased the cubic feet of required cooling, so I upped the air exchange and decreased the room volume. Problem solved. I moved my 6" vortex to cool the garage at night and it exhausts into the main greenhouse so it keeps my flowering plants warmer at night. add to this the dehumidifier that runs at night (and when it's pouring rain) and I have the means to minimize excessive temp variations. Neighbors are blown away that I have no molding problems. I'm blown away that anyone would even try to grow outdoors here. This is my first crop in this system. The strain is The Black and when I got these plants they were already stretched from poor care. I'll probably only get 3-4 ounces per plant. :/ The "kids in the hall" pictured are Booger and Pineapple Express. I expect to increase the yield of my second round significantly.
Pictured: Pretty little Booger I'll be keeping my eye on and my "Oh Shit!" door fan which I haven't had to use since I got the temps under control. Ya never know.