Homemade Greenhouses

Discussion in 'Outdoor Growing' started by happy smoker, Nov 13, 2011.

  1.  
    happy smoker

    happy smoker Active Member

    Well this year i have decided to build a greenhouse, and was wondering if anyone wanted to show theirs off. I have got an idea of what i want the frame to look like, but im trying to figure out what to cover it with. I need something that wont break the bank and is not completely clear. Thanks.
  2.  
    dudemandigo

    dudemandigo Well-Known Member

  3.  
    happy smoker

    happy smoker Active Member

    Has anybody on here actually wraped theirs with the polyethylene, if so post a pic.
  4.  
    TWS

    TWS Well-Known Member

    hello Happy smoker. Good conversation piece. A lot of these ideas are credited to other members but there are alot of ways to build an inexpensive green house. Hoop houses made with PVC are real easy to do and a lot of members just enclose a portable carport. They can be found cheap on craigslist or ebay. I framed mine from my excisiting patio balcony post. Far-Tek is where you might want to get your agricutural plastic. Check their bargin bin.

    http://www.farmtek.com/farm/supplie...nhouse_covering_2;ft1_greenhouse_films_2.html

    Bargin bin:

    http://www.farmtek.com/farm/supplie...nhouse_covering_2;ft1_greenhouse_films_2.html


    Heres mine with Farm-Tek product. The sides and top are removable for the summer and fastened with ziptyes.

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  5.  
    justadude420

    justadude420 New Member

    Mine is as simple as I could get it, at least to me. Only thing I bought was PVC,Gorilla tape,zip ties and plastic. It cost me just under $250 to make approximately 13 foot wide, 9 foot high, 40 foot long greenhouse. I kept cost down by using things already available to me. PVC pipe attached to the back of my fence, hooped and attached to the chain link fence that was already there to keep my dog from breaking into the neighbors backyard. 100_2268.jpg
  6.  
    TWS

    TWS Well-Known Member

    Your green house is nice ! I might have to hoop out a smaller one in a different part of the yard where there is more sun this time of the year.
  7.  
    justadude420

    justadude420 New Member

    I really like yours too, I think I figured a way to do it without the fence.....I think the cheapest way would to just get a bunch of rebar and pound them into the ground like a bunch of huge stakes, then pvc over them and attach somehow. If you have a lil money or lumber you can make a wood frame on the ground and attach PVC.
  8.  
    TWS

    TWS Well-Known Member

    The rebar was my first thought, The frame idea is a good one too.
  9.  
    happy smoker

    happy smoker Active Member

    Thanks guys those are nice. I was thinking of using 2x2 for the frame, but i am going to check on pvc pipe. Do you all ever have pest problems with the greenhouse? Every year i get those worms that bore into the stalks, and end up losing half my crop. I am thinking that a greenhouse will help out.
  10.  
    justadude420

    justadude420 New Member

    It helps alot, I still got a few budworms only due to putting up my greenhouse too late while 3 of 5 were flowering...I also had the sides open with netting during the hot hot summer days. It did help keep out the butterflys but some moths are tiny and lots were still getting in at night and I didn't realize it until it was too late. I used Safer Brand caterpillar killer to get rid of the problem, covered with 5 mil plastic and since then have not seen any or had any more damage.

    Harvested indica in oct, lost about 6 oz total from those 3 plants to budworms. Just harvested the sour diesiel nov, didn't lose a gram to budworms...So yes it will help. 100_2163.jpg
    next year I will make sure I roll down the plastic at night to keep moths out if it have the sides open again.....just got too hot fully covered.
  11.  
    happy smoker

    happy smoker Active Member

    That was my next question , how about the heat and humidity . I want mine fully enclosed with some kind of fine screened vents . Around here it can get to 100 degrees with 80 to 100 percent humidity, so I know ill need some fans.
  12.  
    justadude420

    justadude420 New Member

    Well if you have enough money you can always use fine screen on both ends and it will have a tunnel of brezze or add the fans if you want. I thought about fans but , went the lazy cheaper route and left both ends and the front open with netting. It got really hot, but I got the delta brezze blowing right thur and they seemed ok.I just watch the plants they pretty much let you know if something is wrong, we had a few days where it was over 100 and they handled themself fine.
  13.  
    TWS

    TWS Well-Known Member

    Heat and humidty are of concern when using a greenhouse. Like justadude mentioned the screen method is a good idea in the summer when it gets hot. We have consective days over 110 where our plants would not be happy enclosed and direct sunlight is best so in the summer it's opened up. Humidty and condensation are harder to deal with which in the winter when you need your greenhouse is when it's at it's worst. Fans,heat and freash air are needed. Unless you spend a lot on a heater,fans(intake&exhaust) and A/C a fully enclosed unit is hard to do for something that doesn't like moisture when flowering. As far as caterpillars go,spray for them and no problems.

    Hope it's not these you have.
    Beetle Borers

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    Prevent: Beetle borers are primarily found in outdoor gardens. Cleanliness and good habits will keep these pests out of greenhouses and indoor growrooms.
    Identify: The beetle borer is the larvae of a large variety of beetles and a particularly nasty pest. These larvae leave entry holes at the base of stalks where they continue chewing through the stems of your plant. A brown trail of death will follow the path of a beetle borer, these pests cause severe enough damage to water transportation systems of plants everything around the trail dies. If the base of branches or heaven forbid the main stem of the plant are infected, death can quickly follow for everything outwards of the trail.

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    Note the entry hole on the left of the picture and subsequent trail to the location of the larvae

    Eradicate
    Repression: Keeping indoor grows clean is the only countermeasure.
    Predators: The borer is a large enough tunneling insect that no effective predator has been identified. Predatory nematodes can help control grubs in the soil but this is a largely preventative measure and not a treatment.
    Manual Removal: The best and virtually only way of controlling beetle borers. If damage is sited, follow the trail and cut the borer out of your plant. Oftentimes damage is already done when a beetle borer is located. If the branch or affected area does not bounce back quickly or is obviously done for, remove it with a clean cut from a knife or scissors.
    Spray: The beetle borer lives inside the hardy stalks of your plant making sprays nearly useless. Bacillus papillae is a beetle specific fungal powder and can have limited success. If the beetle is in the main stem of your plant and you cannot get to it without endangering the life of your plant, injecting a product called rotenone directly into the stalk with a hypodermic syringe will kill the grub





    Some Climate control info.


    Greenhouse condensation.
    Today was the first day of the greenhouse being fully enclosed in after a rainy day. When I finally woke up this morning at 10 am ( gotta cold) the walls and cieling were pretty wet and it was pretty warm and steamy in there(some water came in at the walls because they werent done all the way when it rained). Actual steam as it was nice and sunny today as everthing was drying out from our good first storm system. I opened the door and hadn't yet secured about a foot of the top in the back so I pealed that back to and opened up the floor vents and cooled it down and let out the humidty. The condensation cleared out mostly by the end of the day. Tonight We have a fan running in there and will use a heater if necessary later.

    My research:

    Greenhouse Condensation
    J. Raymond Kessler, Jr.
    Auburn University​

    Have you every walked into a greenhouse early in the morning on a cool, crisp spring or fall day, slammed the door behind you, and found yourself soaking wet? You look up to try to find the source of this indoor precipitation and see rows of big, fat drops of water coating the inside of the glazing. With a sigh, you walk among the benches of plants and observe a film of water coating the leaves, and maybe a spot or two of gray, fuzzy mold growing on a leaf or flower petal. Other than your discomfort, should this drippy deluge be a concern for the health of your crops? Certainly it should! High relative humidity at night and condensation cannot only lead to disease problems, but will also reduce light intensity. So, what conditions lead to this problem and what steps can be taken to prevent the problem?
    A unit for measuring the amount of water dissolved in air that is familiar to most people is relative humidity (RH). Relative humidity is a ratio between the amount of water dissolved in the air to the maximum amount of water the air can hold at a specific temperature and atmospheric pressure. From a practical viewpoint in a greenhouse, atmospheric pressure changes will be so small that a constant pressure can be assumed. Therefore, greenhouse relative humidity is the current concentration of water in the air divided by the maximum amount of water the air could hold at a specific temperature, expressed as a percent.

    Current water concentration in air
    RH = _______________________________________ × 100, at constant temperature
    Maximum water concentration the air could hold

    The discussion above assumes a specific temperature, but temperature within a greenhouse change under various conditions, e.g., day to night. Suppose that a container of water is placed within an enclosed space (similar to a greenhouse), water molecules evaporate into the air of the enclosed space until equilibrium is reached (similar to plants, floors, etc. evaporating water in a greenhouse). At equilibrium, the air is saturated with as much water as it can hold. When the temperature of an enclosed volume of air at a certain RH increases, the air expands and can hold more water. If no additional water is added, the RH decreases. Conversely, when the temperature of an enclosed space at a certain RH decreases, the air contracts and can hold less water. The RH increases as long as water does not condense out of the air.
    Figure 1 shows the relationship between RH and temperature and is called a psychometric chart. For an example of this relationship, suppose the temperature in a greenhouse is 70°F during the day and the RH is 40% (small dotted line). If the temperature at night drops to 60°F, the RH increases to 50%. Conversely, a 10-degree increase in temperature will decrease the RH. In reality, the amount of change in RH is about 2% for each 1°F change in temperature.
    Now suppose the temperature in a greenhouse is 75°F during the day and the RH is 50%. If the temperature at night drops too just below 45°F, the RH will increase to 100%. Any further temperature reduction and the concentration of water in the air will rise above the saturation point and condense as water droplets. This is called the dew point.
    High RH in a greenhouse is important in relation to the incidence of several foliar diseases, especially Botrytis and Powdery Mildew. Powdery mildew spores germinate best a 95% RH or higher. However, low RH and high temperature are needed for fungal maturation and spore release. Diseases related to high RH are usually more common in the spring and fall when environmental conditions are highly variable. Diseases due to high RH are usually not a problem during the heating season because raising the air temperature using heat lowers the RH. Air vented into the greenhouse during the winter may be very moist, but is also very cool. Heating this moist, cool air reduces its RH. In the summer, the RH of outside air is usually lower than the air in the greenhouse, so ventilation is the most practical means of lowering inside RH.
    The spring and fall often have warm, bright days and cool nights and the moisture content of the outside air is high. In the early evening as temperature drops, ventilation does little to decrease the inside RH. As the temperature drops at night and ventilation stops, the RH can be very high even though the greenhouse many not be cool enough to require heat.
    Leaf temperatures during the day are usually a few degrees warmer than the air temperature because they absorb sunlight. After sunset, however, the leaves may radiate heat through the glazing to the cooler air outside (radiation cooling) resulting in leaf temperatures below the greenhouse air temperature. At high RH in the greenhouse, the dew point is reached in a thin boundary layer of air around the leaves and a film of water forms on the leaves. This free water is an invitation to diseases.
    The best way to prevent water from condensing on leaves during the spring and fall is to provide constant internal air circulation and, if necessary, heat the greenhouse for a short period of time in the evening with a ventilation fan running. Internal air circulation from horizontal airflow fans or similar methods prevents formation of a saturated boundary layer around the leaves and thus prevents condensation. If high RH is a serious problem, place one ventilation fan on a time clock so that it will turn on about 8:00 or 9:00 PM in the evening. The fan should run just long enough to complete one air exchange of the greenhouse. The warm, moist air in the greenhouse will be removed and replaced by cooler, moister air from the outside. The cool outside air should activate the heating system and bring the greenhouse air temperature up to the set point. The moist, cooler air from outside will warn-up and have a lower RH.
    During the winter, the temperature difference between the greenhouse air and the outside air can be large. The glazing material loses heat rapidly and becomes cold. Warm, moist air circulating over the inside of cold glazing can reach the dew point and water condenses on the inside of the glazing material. With glass, condensation dripping is usually not a big problem because of the surface tension properties of glass. Water tends to spread out into a thin film on glass. However, the surface tension properties of plastics are such that condensed water very quickly forms large drops that can rain down on crops in the greenhouse. This problem is especially serious in houses covered in polyethylene.
    Covering the greenhouse with two layers of polyethylene and creating an air space between the layers by inflation insulates the inside layer and reduces the temperature difference between the outside and inside. Internal air circulation and heating the greenhouse with a fan running in the evening also helps. New polyethylene products have been developed with a special coating on the inside to reduce the surface tension and thus reduce dripping. Be sure to install this kind of polyethylene with the coated side toward the inside of the greenhouse!


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  14.  
    vinniekaz

    vinniekaz Member

    If you have worms boring into the main stem, and you can see the entry hole, use a thin piece of wire, and insert it into the entry hole as far as you can and spin it around. The wire will assault and injure the little bastard in his "safe" home. The larvae will usually drop out of the hole as soon as the wire is pulled out....makes it easy to crunch and kill them quickly.

    Found this out by accident one day. I found a brown hole in the base of one of my larger plants main stem, so I "probed" it with the wire. As soon as I pulled the wire out, the worm dropped out of the hole and started wriggling all over the place. I quickly sent him, and all of his other friends, to worm heaven!

    Good Luck

    Vinnie Kaz
  15.  
    happy smoker

    happy smoker Active Member

    Those are the ones that i get. Hoping the greenhouse will help.

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