8 minute read
Growing Greenhouse Cannabis – THE BASICS
Cannabis grown in a greenhouse can be set up in either one of two ways. The grower may grow the plants in separate containers or pots, or plant them straight in soil. There are advantages and disadvantages for both options, but basically it depends on what fits best for the producer’s production site and his business strategy.
By choosing the container route, it makes it easier to move the growing plants whenever necessary. This is particularly handy as one can simply move the plants elsewhere. Another reason to move the container-grown plants might be if the greenhouse or shade net structure needs replacement. Should the grower wish to plant cannabis directly into the ground on the other hand, the plants will produce much better when they are left alone for a longer period of time (such as a week). Naturally, this is only to be expected if the soil they are planted in was properly prepared with the necessary nutrients and remain at the right pH level.
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Another option exists for more innovative greenhouse growers:
hydroponics. Producers who used this method in a greenhouse have had big success, making it a potentially good idea if it suits your lifestyle and experience.
Of all the growing
methods, hydroponics is known to provide the highest potential yield. If done right, growing marijuana in water indoors can maximize your plant’s growth.
Cannabis genetics
The most important advice is to buy high-quality cannabis seeds. It is worth the extra financial outlay to be assured of setting up for a successful growing season. Should the grower obtain poor quality seeds instead, then he may not achieve the same level of success, no matter how much effort and time is spent on caring for the plants.
Buy high quality seeds to get best result
One of the best things about really intensive greenhouse growing is that it can be highly automated. In other words, it can be much easier for the grower because they don’t need to do as much day-to-day care for their plants. One such automated system is a watering system that delivers water to the plants automatically, or with little effort on the grower’s part.
Automatic irrigation in the greenhouse (Pic GPN news)
A grower may want to consider installing some automated systems of your own if he is technically innovative and enjoys planning such things ahead of time; if he has a high enough budget for it, and if he don’t enjoy the daily tasks of cannabis plant care as much as the setting up process.
Important: Security
A good way to keep the cannabis plants safe from detection if the greenhouse is not located in an inconspicuous or private location, is to paint the exterior with white shading paint. You can find this at a garden centre, and it serves the dual purpose of preventing the greenhouse from getting far too hot on the warmest days during the summer. When you have a painted greenhouse, people will not be able to peer inside and identify what you are growing.
Start early
To truly take advantage of growing cannabis plants inside a greenhouse, try starting the growing season early this year. This is possible as greenhouses get much warmer than the outside temperature once the sun is out fully.
More sun makes it possible to start growing earlier
Since the growing season is started earlier, the producer has more time for the vegetation phase of the cannabis plants. When you have more time for the vegetation phase, your cannabis plants will be bigger and stronger for the flowering phase. As a result, your harvest at the end will be much better. The key to doing this successfully is not to allow the greenhouse to get too cold at night during the early part of the season. You can do this by installing greenhouse heaters, found at your local garden centre, to be run during cold nights. This ability to lengthen the growing season for cannabis plants is one big reason why, and an increasing number of cannabis growers are opting to grow
their plants in a greenhouse instead of an indoor or outdoor setup. These plants have the opportunity to grow far greater in size than their outdoor counterparts, assuming the seed genetics, soil, and other care aspects are sound. Believe it or not, some growers have even opted to grow just one big plant in their greenhouse setup — and that plant gave them hundreds of grams of high-quality buds at the end of it. If the plant starts getting too out of control, it could actually start growing out through any open windows that might be in your greenhouse, and therefore steps need to be taken to “tame” the plant. This is best done via tying techniques.
One big plant in a greenhouse
It is a good problem to have, but growing gigantic cannabis plants is not necessarily an easy thing to deal with. Properly grown, fully maximized cannabis plants cultivated in a greenhouse will be tall and extremely bushy. This is particularly true if you have been giving your plants huge amount of space in the soil for their roots, good quality soil to begin with, land lots of sun. Make sure you are prepared for the “worst.”
Using a darkening system
Many greenhouse growers will opt to use what is known as a “darkening” system which, when set up correctly, should be dark enough that there is a complete blackout within the greenhouse — even during the middle of a sunny afternoon. The point of installing a darkening system is to simulate shorter days and longer uninterrupted nights, thus spurring your cannabis plants into an early flowering phase.
Maximizing your cannabis greenhouse setup
This is an expensive addition, but it will certainly ensure that you acquire your cannabis much faster than if you waited for the natural sunlight conditions to change over the course of the season. The way to “trick” your plants into entering the flowering season early is to have 12 hours of uninterrupted darkness and 12 hours of sunlight every day without fail. The darkness is the most important part of this process — you must not allow any light in at any point, even for an instant. After a couple weeks of this, you should start seeing signs of flowering.
Extending the growing season
A greenhouse can also be the perfect environment for manipulating the length of the end of your marijuana plants’ growing season. Many growers choose to use this to their advantage and lengthen the end of the growing season.
High yield while growing in a greenhouse
The main reason why a greenhouse is beneficial in this way is that it keeps the air around the plants (in other words, the air inside the greenhouse) toasty warm when it is sunny while the colder temperatures of autumn are creeping in. Source: Growing Marijuana by Robert Bergman
Read more about greenhouse cannabis growing in the next edition of Undercover Farming.
14 WATER QUALITY
that Zn be used at 0.33 mg L-1 for substrate-grown tomatoes, but toxicity can be expected at only twice this concentration. High Zn-levels are usually found in water gathered from galvanised roof surfaces. Copper-sulphate is a well-known chemical, used to kill algae in swimming pools. Thus, the potential phytotoxic effect of high Cu-levels is well-known. Most crops need Cu at 0.05 mg L-1. According to Steiner (1984), Cu may be phytotoxic when its concentration is doubled to 0.1 mg L-1. Copper pipes should thus be avoided in hydroponic units.
Manganese toxicity problems may
develop on lettuce (open or loose tulip shaped heads) where seedlings are raised on sphagnum peat, due to high levels of Mn in this European substrate. High iron (Fe) and manganese (Mn) levels in some feeding water sources may block irrigation drippers. These water sources should be treated to lower Fe and Mn levels.
Total alkalinity (pH)
The pH of water and nutrient solutions can be manipulated by adjusting the total alkalinity. Total alkalinity is the aggregate concentration of carbonate, bicarbonate and hydroxide. The total of these ions (CO32- & HCO3 - & OH-) in water is determined with a titration, by adding acid to the sample until the pH reaches a level of 4.5. Some water-soluble fertilizers may be slightly acidic. Thus, the total alkalinity of the water should not be too small to prevent the pH from dropping when these fertilizers are dissolved. It is important to adhere to these factors when serving greenhouse plants with a balanced diet of water through the irrigation system!
Aquaculture: Biological Filters prevent Poisoning of Fish
In recirculating aquaculture systems (RAS) water is cycled continuously from the fish through filtration and temperature control systems, and back to the fish. The temperature control enables one to farm fish species under ideal conditions year round, getting them to market sizes on time, disease free, with improved health, reducing mortalities and enabling producers to farm the fish outside of the natural climatic zones.
“However, to best justify the capital cost of a RAS, we hold the fish at the same sort of high densities that are used in cage farming, resulting in lots of metabolic wastes being released into the water. This in turn would poison the fish if it was allowed to accumulate, and the biological filter (biofilter) is there to prevent this from happening,” Leslie Ter Morshuizen of Aquaculture Africa said.
Many types of biological filters have been used over the years but in the past 2 decades an almost complete shift came by using fluidised filters. Inert, neutrally buoyant media is placed
