Growing marijuana hydroponically simply means that you grow the plants in an inert, sterilegrowing medium instead of in soil. All of the plants’ nutrient requirements are supplied when you mix water with the nutrient solution. Plants are 80% to 95% water; the remaining parts are carbon, oxygen and hydrogen. Plants extract these elements from the air and water so nutrients are actually a very small amount of the total weight of a plant. It is the plants entire atmosphere that needs to be controlled within the hydroponic environment to produce perfect crops.
Marijuana plants, and in fact all plants, do not need to be in a living soil, they require nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and sulfur (S). Those are the macroelements (the big ones) and the small elements known as microelements are iron (Fe), chlorine (Cl), manganese (Mn), boron (B), zinc (Zn), copper (Cu) and molybdenum (Mo).
Hydroponics introduces the water, nutrientsand air to the roots through the growing mediums and since using hydroponics bypasses the web of roots and the energy required for the plant to acquire the nutrients you get faster growing plants.
Hydroponic marijuana set ups
All growing described on this page is done using the Ebb and Flow system. The Ebb and Flow system is one of, if not the most popular hydroponic methods for growing weed. It is simple and easy to use.
It works like this: A reservoir containing nutrient solution is located below a growing tray. The tray contains the plants that are in containers with growing medium like Rockwool.
The growing bed is filled with nutrient solution by a small pump on a timer to feed and water the plants. The timer then shuts the pump off and the nutrient solution drains freely back into the reservoir.
Ebb and Flow systems’ are favored because of their low maintenance, high productivity, and ease of use. Ideal not only for the beginner, but for the advanced gardener as well.
Sea of Green (SOG) and Secret of Green SCOG – growing systems are used more by commercial operations where speed and yields are paramount but can be used in smaller home grows. The equipment is different and you need cannabis strainsthat are capable of flowering after a short vegetation period.
If you would rather buy a ready built grow room rather than grab all the gear from the hardware store (they will know what you are making), it may cost a little more but all parts will be included and you will save time by getting everything at once. It’s possible to get an 8 plant unit setup for around $300, ebay has a lot of inexpensive gear.
Marijuana lighting
Since modern hydroponics began people have used high intensity discharge (HID) lights like metal halide or high pressure sodium (HPS) to grow marijuana. Metal halide light is close to regular room light or cool fluorescent light and is more abundant in the blue and green spectrums which is best for vegetative growth. While high pressure sodium is in the orange, amber and red end of the spectrum which is best for flowering stage(later) growth. Growers often use these two lights in tandem, MH for vegging and HPS for flowering or both at the same time. Marijuana grows well from 420 through 730 nanometres which can be covered in this method. HID lamps like the MH and HPS offer a lot of light but just as much wasted energy is emitted as heat. You will need to manage that heat with a good ventilation system. HIDs also require a ballast to operate so make sure you buy one of them. Expect to pay about $250 for a 250W HPS/MH digital ballast, bulb and reflector combo.
Broad spectrum LED grow lights are the new breed and offer a number of advantges over HIDs. Broad spectrum LEDs cover the 420 to 730 nanometres growing range and run on 82% less electricity. A 1000W HPS is the equivalent to approximately 185W LED. Good LEDs run cool and emit very little heat; the LEDs last for an amazing 50,000 to 60,000 hours and don’t require a ballast. LED grow lights are a great solution to the old HIDs.
Marijuana growing seeds or clones
If you know someone who grows, ask them for a few clones. If you don’t have access to clones you will have to buy marjuana seeds. If you don’t already have some, you can ask you friends to save you seeds out of any good weed they may come across.
Germinate the marijuana seeds
Set up your hydroponic garden before you germinate the seeds. Make sure everything works fine. If you are using clones, skip this section.
There are various types of media available to grow in. Rockwool is one, but there are many others. Media simply means the substance that the roots grow in. Since you aren’t using soil in a hydroponic garden, you need a substitute. The media will provide no nutrition; it is just a support for the roots. All nutrition comes from the hydroponic solution.
The standard thing to do is use a Rockwool cube to start the seed on and surround it with whatever growing media you use. Keep the Rockwool cube so that the bottom 70% or so is submerged when the water is at its maximum, but keep the top part above the water so that the seed is never submerged. After the seeds have germinated and the root is about a quarter of an inch long, place the seed, root down, on your grow cube or media in your hydroponic cups.
Vegetative marijuana growth
The first phase of marijuana growth is called the vegetative phase. If you plan on using LED, MH or HPS right away, Start with about 20 inches or more above the top of the plant (less for LEDs) and lower the light an inch or so daily until you think the height is right. Too close and the plants will dry and turn brown. Too far and the plants grow too tall as they stretch to get closer to their light source. That is a waste of space. Start high and lower the light an inch or two daily until you think the height is right and the light emitted is being caught well by the plants.
During the first stage of growth, the vegetative stage, keep the light on 18 to 24 hours a day minimum. The longer it is on, the faster the plants will grow, but the higher your electricity bill will be.
Marijuana flowering
Flowering is the phase of marijuana growth that produces the most THC, CBN and CBD; these are the active ingredients that produce a high when the female buds are smoked. Once flowering begins, the height of the plants will taper off as the plant energy is used in the flowering process itself.
You can start flowering when the plants are a minimum of about 6 inches high and have at least 4 sets of leaves. This will take 2 weeks to a month of vegetative growth in most hydroponic gardens. When you want to start flowering, cut the light back to 12 hours a day.
If you start the flowering when the plant is very small say 6 inches the height of the plant will continue to increase for about two to four weeks after flowering has been started, after that all the plants energy will be used for flower production. If you start the flowering when the plant is a bit more mature it will start in around 10 days.
Limiting the height of a marijuana plant has always been a difficult task, so one easy method is to raise the height of the light as the plant grows. There are methods of limiting the height of a plant, but none of them are really easy. We recommend one of the Marijuana Growers Guide which has the most comprehensive descriptions I have seen on limiting the height of weed.
The flowering cycle lasts about two months, sometimes a little longer, depending on the type of seed. So the total length of time to raise a crop should be 3 to 4 months in a hydroponic garden but much less if you use the Sea of Green or Screen of Green methods.
During flowering the dark period must be perfectly dark. No room light, sun light, or any other light should reach the plant in the 12 hours of darkness that the plant must get everyday. The strongest light that should reach the plant during flowering would equal that of moonlight. Stronger light than this will delay flowering, and if it continues there is a chance that the plant will not flower, but stay in the vegetative phase.
You will know the plants are flowering when you see what look like little white hairs developing at bud sites. They should be visible after about 10 to 14 days of the flowering light cycle. This is when you need to remove the male plants, not required if you have female clones. These pistils will eventually be the red or white hairs that you see turn into nice big buds.
From: howtogrowmarijuana.com
