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What are the Advantages of Growing in a Greenhouse?

Smokin Moose

Fallen Cannabis Warrior
A greenhouse is any structure with a covering (usually glass) which is used to control temperature and humidity in the cultivation and protection of plants.

When you have a greenhouse, you effectively have your own little micro-environment that you can control. You become the God of your own little patch of land! Greenhouses don't always have to be made out of glass. Many modern greenhouses are made of plastic, or specialized materials. These materials come in a variety of color, size and thickness. Choosing materials carefully will ensure you have the best greenhouse for your situation.

Greenhouses can be simply DIY jobs using some timber and a drill, or poly tunnels using poly tubing and some polythene sheets. They can also be large custom built structures, using metal and concrete. For most people, a small DIY greenhouse (about 10-20 square meters) will do just fine.

What are some advantages?

Ability to control temperature
The greenhouse design lets light in, and when this light is absorbed by objects inside the greenhouse and turns to heat energy, it is not permitted to escape. The air temperature in the greenhouse will exceed the outside temperature. If it gets too hot, all you have to do is open up some of the ventilation panels (or just open the door, depending on the design) and the temperature will drop. Greenhouses are able to regulate temperatures; temperature fluctuations can stress plants and slow growth.

Ability to control pests
As most greenhouses have a pretty good covering over all the structure, pests can't get in as easily as they could if your plants were just out in the open. This also applies to seeds and even pollen from unwanted plants (such as weeds).

Ability to control humidity
The air-tight covering on a greenhouse causes it to become quite hot and humid inside during the day time. The moisture evaporating from the soil, and the moisture given off by photosynthesizing plants (transpiration) fills the air. Once the air is very humid, it becomes harder for plants to lose water through evaporation, and likewise with the soil. This helps to keep everything from drying out on a hot sunny day. Therefore, it is essential to have air circulation to exhaust excessive humidity and regulate air exchange.

Stealth
Nosey neighbors will have their view obstructed by your greenhouse if you choose to use slightly shaded glass/plastic, which still lets enough light through for strong plant growth, but is opaque enough as to obscure vision from the outside.

Protects your plants from adverse weather conditions
Storms can't blow your plants over and tear them to shreds when they're safely inside your greenhouse! Also helps protect plants in areas where frosts are common.

Excessive fall rain can cause powdery mildew and mold that can effect the final crop.

How does all this environmental control help?

How do higher temps help my plants?
Every plant is made up of cells. Every cell has hundreds of chemical reactions taking place inside it at every moment of the day. These reactions would be very slow, if it wasn't for enzymes. Enzymes act as catalysts for all the chemical reactions taking place in cells (including photosynthesis).

Enzymes work best in certain pH's and temperature ranges, depending on the type of enzyme. Too high or low pH, and the enzymes will work slower than normal, or might even denature (die). Too low a temp, and the enzymes will also not function to capacity, and too high results in them being denatured. Warm -but not hot- temperatures usually result in maximum enzyme efficiency, which means faster plant growth. Having perfect temperatures is like super-charging your plants!

How does higher humidity help my plants?
It helps slow the rate of evaporation from soil and plants, as the air already has a large amount of water suspended in it. Plants use water during photosynthesis (6H20 + 6CO2 (plus sunlight)= C6H12O6) so they need a constant water supply during sunlight hours. Having to battle with high evaporation rates is something they don't want! By lowering this, it enables them to photosynthesis more without losing water to the point of their leaves wilting.

Other advantages
A greenhouse is a great idea for outdoor growers who live in cold climates, or areas where pests and horrible acts of god are a common problem. It also helps hide your crops from anyone who may be having a quick look over their fence. If you want maximum control of your outdoor grow, a greenhouse is an absolute essential part of your garden!

Are there any disadvantages to growing in a greenhouse?
Well, no not really! Growing in a greenhouse is more-or-less just like a regular outdoor grow, except you have much more control over it. The one thing I would say might be a bit disadvantaging would be the humidity. It may increase the risk of mold on your buds. This is easily fixed by opening the greenhouse up a bit and letting some more fresh air in. If you're paranoid about mold attacking your plants in a greenhouse, you can use Potassium Silicate to protect your plants, which is easily available at most gardening/hydroponic shops.

NOTE - Depending on the size, and construction of the greenhouse, you may or may not need permission from local authorities. If they want an inspection, it's probably best to have it cannabis-free for a month or so.

If they want further inspections, it might be a good idea to grow all your 'special' plants in pots, and keep the greenhouse door LOCKED. When someone comes around for an inspection, simply hide the plants somewhere else until the inspection is over. I have never heard of a medium size suburban greenhouse needing to be inspected once, or on a frequent basis. Although, it may be best to check this with local authorities, just to be safe.
 

420 stoner

New Member
is there different types of sheets for greenhouses? & do some stores that sale greenhouses sheets sales them by rolls? some help would be nice thnkz
 

WillyBudz

New Member
You can get 4mil (and thicker) opaque or clear plastic sheet rolls at any ACE hardware cheap in Colorado...

Some 2x4's, nails / screws, a heavy duty stapler and a roll of this stuff and off you go.... I have an 8'x8' homemade green house using these materials. It is not setup for winter in Colorado.... YET ...but, rocks spring >>> late October early November. Big enough for 4 8' tall and fat shrubbed plants with room to get around them and work. If I wanted it to be a pain to work in I could fit 8 plants or so in it but 4 monsters give me plenty of fall product.

:peace:
WillyB
 

SemperHighGuy

New Member
I used lumber for my greenhouse. 2x4s and 2x10s. I have two and each one is 150 square feet. I installed a solar fan and I water by hand this year. I am going to simplify the watering system I designed for another grow system.

Being from Northern California is nice. What is a good greenhouse strain? I'm going to try White Widow next season I think. Perhaps 20 plants. We shall see.
 

Vytas

New Member
We have a 9X16 from Santa Barbara Greenhouses that I built from a kit for our orchids. This year I have done my 1st grow. One advantage not mentioned is the ability to induce blooming by using shade cloth to restrict the amount of light hitting the plants. I have learned that rolling the shade over the roof causes the girls to flower. I also have shade cloth on the sunny end and the sides, this was done for the orchids and the cloth is the 70% sunblock. The greenhouse is situated so that it is in shade from about 4 in the afternoon so it is easy to lower the light input below the level necessary to induce blooming. My plan is to roll back the cloth later in the season and maintain the light levels to promote longer flowering in the fall.

The only downside is that the plants get too big if you put them in too early in the year. I started with 6, but now have thinned them to 3. They are about 7 feet tall and fill the place from one end to the other and from side to side. I have to crawl in on the floor to service the nutrient tank. This year I planted my seedlings and clones on April 1, far too soon, next year I will wait until late May or June.

I was very aggressive topping and they bushed out nicely, just got soo damn big!! Now I am getting thousands of buds at all the nodes, most about an inch long so far, been blooming for two weeks now.....

I use an ebb and flow system with a 30 gallon reservoir and use RO water. I supplement with Calcium and Magnesium and feed with GH Flora Nova. I am a busy guy and my routine is to check the nute level in the morning and ignore it the rest of the time. I have to refill the nutes about every 5 days which takes about 1/2 hour. I guess I spend about an hour a week total on the grow and have had no bugs or problems as long as I keep the PH in range. Before flowering, I could leave the grow unattended for a week at a time, just cut the girls back from flowing every hour to every other hour and the reservoir lasts for over a week...... We got back from 10 days at Lake Powell to find things green and healthy without any tending at all.
 

SemperHighGuy

New Member
I have a question about the shade cloth. Does it increase the temperature in the greenhouse? I was thinking about using it to keep the greenhouse warmer in winter months by using it as a curtain dividing the greenhouse.
My plants are well over 7 feet tall. Monster plants. I've grown indoors for quite some time and each of my plants are equal to 3 or 4 indoor plants.
 

SemperHighGuy

New Member
Once these plants are harvested and the other greenhouse expanded I am going to devise a watering system. Got most of it worked out in my head. I will use a mist system early on to foliar water/feed and a system to water once the plants are in te ground. I am using well water that has a ph of 7.1 and once the Bio Bizz is added the ph runs about 6.3-6.5.
I'm using paracord to tie to the chicken wire and so far works great! I'll start a journal next year on this forum with images to chronicle the journey.
 

Vytas

New Member
I have a question about the shade cloth. Does it increase the temperature in the greenhouse? I was thinking about using it to keep the greenhouse warmer in winter months by using it as a curtain dividing the greenhouse.
My plants are well over 7 feet tall. Monster plants. I've grown indoors for quite some time and each of my plants are equal to 3 or 4 indoor plants.

The shade cloth seems to keep the place cooler by blocking most of the light energy, UV and IR that gets to the interior. I hooked up a small evaporative cooler when I built the greenhouse that keeps it at whatever temp I want. This year it has been set to 9O degrees F. There are also automatic opening vent windows in the ceiling to allow the cooler, more humid air from the cooler to displace the hot air.
 

Vytas

New Member
Once these plants are harvested and the other greenhouse expanded I am going to devise a watering system. Got most of it worked out in my head. I will use a mist system early on to foliar water/feed and a system to water once the plants are in te ground. I am using well water that has a ph of 7.1 and once the Bio Bizz is added the ph runs about 6.3-6.5.
I'm using paracord to tie to the chicken wire and so far works great! I'll start a journal next year on this forum with images to chronicle the journey.

If it was me, I would try to get my PH down to 5.8: 6.3 to 6.5 is outside of the ideal range of 5.2 to 6.2.
 

Slippyone

New Member
Great thread.

Got a few questions as I'm looking to buy a greenhouse and put it on my rooftop deck in So Cal.

I guess the size doesn't really matter in relation to my question (12x12x8) but here it is.

Since 12/12 induces flowering, how could I grow in the winter with only about 8-10 hours of sunlight a day (about 6:30 AM-4:30 PM)?
Would I need to supplement my light in the greenhouse to keep it around a 14/10 or perhaps 16/8 light schedule in order to keep them vegging as needed?
Frost isn't a problem and wouldn't be w/ the Greenhouse as temps rarely get below 45 here at the beach.

Thanks for your help in advance!
 

Chobble

New Member
Great thread.

Got a few questions as I'm looking to buy a greenhouse and put it on my rooftop deck in So Cal.

I guess the size doesn't really matter in relation to my question (12x12x8) but here it is.

Since 12/12 induces flowering, how could I grow in the winter with only about 8-10 hours of sunlight a day (about 6:30 AM-4:30 PM)?
Would I need to supplement my light in the greenhouse to keep it around a 14/10 or perhaps 16/8 light schedule in order to keep them vegging as needed?
Frost isn't a problem and wouldn't be w/ the Greenhouse as temps rarely get below 45 here at the beach.

Thanks for your help in advance!

Thats a great question. Over the summer I worked on a Farm in Humboldt, They all used Greenhouses etc. Most of them just grow over the summer, but some people in that area grow in greenhouses year round. Im pretty sure they just put the plants in when they are ready to flowering (Small Veg period or they at least just get the roots started. So what you may want to do, Is invest 200$ in a T5 (Low Heat and Very Efficient) And Veg your plants under there.

Now, Even in greenhouses moisture is going to be a problem so put a fan on each corner of the Green house.

Now what I was going to tell you is, That some people use Black out material (That obviously doesnt allow light through) and put it over there green house for a 12/12 light cycle. (Obviously that requires a lot of effort and you have to be home at the same time every day >.>)

My advise though would be to get a Cheap set of T5's to Veg under for a week or two, Then set those puppys outside and they'll do the rest.

Chobble
 

braabraa

New Member
I found this post very informative. I just started my Greenhouse grow 2 months ago and every thing is going good for the first time. I have had them outside from seedlings to current. I live in Middle Tennessee and it has actually been a pretty mild winter so that can attribute to it. I have mine set on racks with a FL suspended above to give them plenty of light plus the direct sunlight. i also usually cut it off at sundown and turn them back on before i hit the bed, and that has really worked wonders. I have a 80 Sq/Ft GH but with more than just cannabis, I found that the other plants and flowers actually make it more tolerable for the cannabis and so far am yeilding good results. Ill keep the post updated once i harvest..
 

jmac

New Member
ok so im geting my greenhouse in a couple days and had a few questions. since its not really outside and not really inside growing what temperature should i keep my plants at? also i have heard drip water systems work well but are they worth the investment when i can just water by hand everyday?
 

Stoned4daze61

New Member
ok so im geting my greenhouse in a couple days and had a few questions. since its not really outside and not really inside growing what temperature should i keep my plants at? also i have heard drip water systems work well but are they worth the investment when i can just water by hand everyday?


What kind of greenhouse? Mesh walls, greenhouse film, or polycarbonate panels?

You want to try to keep it under 85, however mine sometimes hits 90-100 and I have not encountered any heat stress. But I have constant air exchange with the cool intake air blowing right across the canopy

I would recommend investing in a nice exhaust fan to mount near the ceiling, along with some passive intake vents near the floor. You also need to keep an eye on humidity, if you have over 60% in flower, I would recommend a Dehumidifier! You don't want moldy buds after all that hard work. If you live in a hot & humid climate you could consider an Air conditioner because it cools & lowers humidity

Drip systems have pros & cons. I love mine, I ordered one that waters up to 50 plants for around $30. That is without a timer of course, but I just turn the hose on manually for 30 minutes every 1-2 days. One thing that you have to be cautious about is the drippers will clog from nutrients, so be sure to check that all are working properly every few days. I try to use a watering can for my feedings, and the drippers for my waterings.

If you have under 10 plants I would say it is unnecessary, they don't really improve the growth, it is more of a time & labor saver
 

abbasnaqvi

New Member
Wonderful post indeed. I have a few questions as well. Most of the people who commented above seem to live in colder areas. I live in Pakistan and the temperature in my city rises beyond 45 degrees Celsius in the summers. And a few days definitely come when it crosses 50 degrees C too.

I tried growing in my garage but it got too hot inside without proper ventilation. The pests here are so unforgiving and relentless. They keep coming back.This time i will sterilize the soil and do what not. My QUESTION is, would a greenhouse option be suitable in such a place? If so, how many times or minutes do i need to open my greenhouse to let fresh air in. I know for a fact that its going to get very hot inside the greenhouse. Lastly, how would White Widow perform in these conditions. Also keep in mind monsoon rains (can be dealt with by using waterproof material).
I would very grateful if somebody could help me out here!
 

Blew Hiller

Grow Journal of the Month: June 2019 - Plant of the Month: October 2019
Not sure if I can revive this thread with a few questions. Looking to grow White Widow Female and Northern Lights Auto...first time grow for both. We have a passive solar greenhouse with aquaponics which, from reading this thread, sounds like it will work great. We use fans to move the air through the floor (thermal mass) which minimizes the heat deltas and (hopefully) minimizes detrimental humidity issues.

So here's my question: I am @44'N which gives me 13/14 days in May, June, July, August. (12 hour days occur in Sept.)

When do I start seedlings? Is there such a thing as too early? I've read where autos want more than 12/12, but the regular females want 12/12...correct? Start one strain before the other?

Thoughts & advice appreciated.
 
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