Soilless growing is nothing new, but mastering indoor hydroponic farming to maximize yields requires a full understanding of the history, fundamentals and future of water culture. We break down all of the essential products and techniques to show you how to achieve sensi success, harvest after harvest.
By Erik Biksa and Danny Danko
Hydroponic growing has existed for centuries, going back at least to the days of the Hanging Gardens of Babylon, one of the Seven Wonders of the Ancient World. Over the last few decades, however, the technology for growing without soil has exploded, and there are now many different kinds of hydro systems out there that can be tailored to suit your needs. Whether they use an ultra-fine mist, mimic the natural movement of tides or even deliver a constant stream of nutrient solution, these systems all share a common trait: They deliver water, food and oxygen to the plants’ roots for optimal growth. Sure, growing in soil does that, too – but in soil gardens, you feed the soil, which in turn feeds the plants. With hydro growing, the plant food goes directly to the roots for optimal uptake.
Without a colonized medium buffering what the roots need, a direct relationship exists between what a grower supplies in the nutrient solution and what the plants take up, creating the potential for massive nutrient-absorption rates that will lead, in turn, to heavier and stickier buds requiring shorter grow times.
Many underground cannabis growers favor hydroponics for quicker harvests as well as the added benefit of not having to haul bags of soil or soilless mix to and from their grow locations. Speed and stealth are important considerations when risking one’s liberty to grow a crop.
Today, with medical-cannabis cultivation becoming so widespread, one of the trends in ganja growing has been to simplify things, making it easier and more affordable for the less-experienced “hobbyist” grower to develop a reliable source of high-quality medicine. As a result, we see a lot more “dirt” (or, technically, soilless-mix) grows out there than we used to – and why not? The harvest rates are respectable, and the crop quality can be superb. Also, many less-experienced growers appreciate the forgiving and flexible nature of soil.
So where does that leave hydroponic growing methods such as aeroponics, NFT (nutrient-film technique), ebb-and-flow (or flood-and-drain) and DWC (deep-water culture)? In fact, indoor growers have more options than ever. The newest systems available have more refinement and ease of use built into them, and many are geared specifically to the budding home grower. It wasn’t very long ago that you had to build your own system from scratch, especially if you wanted to grow giant cannabis plants. The few systems available in the old days were designed for general-purpose growing, such as lettuce and vegetable crops with shallow root systems and fast turnaround times.
These days, however, cannabis growers can select from a huge variety of configurations and system types that perfectly suit their skill level and personal needs. Sure, these setups use many of the same principles that were developed by the early hydro-growing pioneers, but their refinement, cost, ease of use, and level of technical support and information make them a great choice for growers of any skill level who are looking to automate their grows, gain bigger yields, reduce watering requirements, speed up growth rates, and avoid the labor and expense of replacing large amounts of grow medium between crops.
The debate will likely rage on forever among growers as to which is “better,” hydroponics or soil, but even the saltiest soil grower won’t argue with the proposition that you just can’t beat the growth rates achieved by hydro. Want a big plant? You can vegetate it for two months in soil or for about half that time (five weeks) in hydro and wind up with a plant of similar stature. The choice is yours.
Water quality is a big factor in growing healthy plants, and growing with hydroponics is no exception. For the biggest and tastiest buds, you need to start with the best quality water. Tap water that has a lot of impurities will lock up nutrients, creating deficient plants that yield poorly and are susceptible to diseases and pests. The chlorine in tap water also kills off the beneficial microbial life that helps plant roots (something that’s crucial for soil growing as well), so always let tap water sit out uncovered overnight to allow the chlorine to dissipate.
Whether you grow using soil or hydro, it’s a good idea to use the best quality water possible. Inexpensive purified water is available in 5-gallon jugs at your local grocery store, but that can still get costly if you have more than just a few plants, so larger-scale growers should consider cleaning their water at home.
RO (reverse osmosis) filtration systems remove nearly 99 percent of the impurities from your tap water and come in a wide range of sizes to suit your budget and needs. Many growers who’ve made do without such a system are often astounded at the improvements they see in their plants after making the switch. After all, most of us are careful about the water we drink, so why shouldn’t we do the same for our favorite plants?
Cannabis has a proclivity for absorbing impurities, which makes hemp (if it’s not for consumption) a valuable plant when it comes to detoxifying soils laden with heavy metals. Unfortunately, heavy metals like lead and mercury may be present in your water supply as well, so that’s just one more good reason to take a look at some type of water-purification system, RO or otherwise, for your medicinal crop. And don’t worry: It costs far less than you might imagine.
Hydro growing was popularized by scientists interested in making commercial food production easier and in improving the yields of plants for every square foot of dedicated grow space. So why not put all this science to work for you?
Sometimes newer growers are intimidated by the idea of growing their plants hydroponically (as are commercial growers with plenty riding on the line). And, as mentioned earlier, there will always be a debate over which method is better – hydroponics or soil – in terms of crop quality and overall yield. However, few experienced growers would argue with the growth rates and ease of automation that hydroponics offer.
Today, one of the biggest trends in ganja growing is raising monster-sized plants. In soil, one of the drawbacks to this is the longer vegetative growth time required, especially for many popular Kush strains, before the plants are flipped to the budding cycle. This can mean upwards of a couple of months of vegetative growth time for plants that finish around the 6-foot mark and yield more than a pound indoors. But instead of taking two months, a highly oxygenated hydroponic system filled with high-quality nutrient solution (and with lots of room left over for the roots to grow) can produce the same size specimen in five weeks or less, all other things remaining equal except for the switch from soil to hydro.
Growers who haven’t yet tried it are often convinced, for one reason or another, that hydro is difficult and will require more of their time. While there are some fundamentals you’ll definitely need to learn, hydro can also be a big timesaver – not only in terms of cropping time, but also the time required for manual labor in the growroom. Manual watering is a real chore when you’re looking at a big room full of plants – so much so, in fact, that crops sometimes suffer because growers are in a hurry or may have other priorities, even as their plants are calling out for water and nutrients.
Hydroponic systems can maintain a constant and balanced supply of oxygen, water and nutrients directly at your plants’ root tips – unbuffered and with nothing to stand in the way of uninterrupted growth rates. Plus the changes can be observed rapidly in hydroponic systems when replenishing your nutrients on a weekly basis. This allows for a more tailored diet for your buds as they develop, giving you the potential for bigger yields, better resin and fewer cropping problems. And don’t forget that healthy and fast-growing plants tend to be more resistant and have fewer incidences of pests or disease.
The Future of Hydro: More O2 for Bigger Yields
As growing technologies continue to progress in terms of nutrients, lighting and environmental controls, the bar for yields and bud quality gets higher and higher (and so do the growers). Naturally, there has to be a limiting factor in all this, and it appears to be dissolved oxygen (DO).
Plant roots need oxygen, which is an essential component for growth. In traditional gardening methods such as soil growing, DO levels are considerably lower than those found in even the most basic hydro setups. Increasing the level of DO that is available at the plants’ root level leads to faster growth rates, healthier plants and bigger yields. That extra CO2 you’ve been adding could prove useless if your crop is gasping for oxygen at the roots, since the plants can only grow as well as their most limiting factor allows. (Sorry, we didn’t make that rule – it’s just in the nature of things.)
DWC and aeroponics are two hydroponic growing methods well known for their ability to deliver significantly increased DO levels to your plants’ roots, while leaving nothing standing in the way of their absorbing water and nutrients, as is the case with systems that use great quantities of grow medium. That’s right: In systems such as these, where the exposed plant roots are bathed (or misted) in a highly oxygenated nutrient solution, the growth rates and yields can be awe-inspiring – and this can even help to remove what would otherwise be a limiting factor to your potential for pot success.
Easy and inexpensive to fabricate, DWC systems normally use opaque buckets or tubs to support plants in plastic mesh baskets affixed to the lid. The roots grow down into the nutrient solution, which fills the tub or bucket and is constantly aerated or “bubbled” by aquarium air pumps, air diffusers or similar.
pH and TDS Meters
A measure of acidity to alkalinity, pH typically plays a strong role in determining how available different nutrients are to your plants. In general, a pH range of 5.5 to 6.3 is considered optimal for most hydroponic growing systems and mediums.
If you want good results with hydro, you’ll definitely need to monitor and adjust the pH and TDs (total dissolved solids) levels that your plants receive via the nutrient solution that you mix in your reservoir. Electronic meters or monitors are the best way to establish constant control. Growers can choose from single-purpose and inexpensive “pen-type” testers to multi-meters that continuously monitor important hydroponic parameters like pH, TDs or EC (electrical conductivity), and nutrient temperature. Some devices even act as controllers and make automatic adjustments in real time as needed.
TDs is most often measured in EC or ppm (parts per million). This measurement tells growers the relative concentration of nutrient ions that are present in the reservoir – or, in simpler terms, the strength of the plant food that your crop is receiving. This is important to know, as over- and under-feeding are two common sources of poor yields and other problems in medical cannabis crops.
pH Up and Down
Usually referred to as adjusters, these are concentrated acids or bases that are added as necessary by the grower (or via dosing equipment) to create and maintain pH levels that are in the optimal range for nutrient absorption. While there are some organic choices available, most growers opt for synthetic chemical concentrates because they’re inexpensive, easy to use and (when used in moderate amounts) will not adversely disrupt the balance of nutrients in your reservoir. If you have to use a lot of pH adjusters in your system, however, you likely have poor-quality water and should consider RO filtration.
Aside from the root zone, you also have to pay close attention to the aerial environment of the plant, and this means watching and controlling the temperature and humidity level during both the light and dark cycles. Most strains prefer a range of 70°F to 82°F. experienced growers will tell you that the most important thing your crops need besides light is optimal temperature. At the least, you need a room thermometer – or, better yet, one that also tells you the minimum and maximum temperature since the last time you checked.
Humidity is a factor that is often overlooked, even by experienced growers. Some have a tendency to think that lower is always better, which is another common mistake. It depends on the strain and phase of growth, but usually 45% to 65% RH (relative humidity) is optimal. This can be measured and even recorded throughout the day using a hydrometer.
If you grow, one of the best $25-or-less investments you can make is to buy an accurate combined digital hydrometer and min/max thermometer. The ones that come with a probe on a cord are especially useful, because then you can see what’s going on in the plant canopy rather than just on the wall.
24-hour water-pump program timer
Even if you choose soil over hydro, you can still easily automate your garden for less work and bigger yields by controlling when your plants receive water and nutrients through the use of a timer. The timer can also help you control how much solution the plants get – and since it’s infinitely adjustable, you can achieve the perfect balance for your plants’ relative watering needs during both their vegetative and flowering stages.
Always use a grounded (three-pronged) timer, especially with water pumps: A grounded timer helps avoid the risk of electrical shock, which is important when you have devices such as submersible pumps coming into direct contact with water. Timers that have a battery backup are also recommended, since your plants’ schedules won’t go all out of whack in the event of a temporary power disruption.
The Hydroponic Grow Tent (or Box)
If you want to start a small to midsize grow without much hassle but with lots of potential for great results, be sure to have a look at the wide range of styles and sizes of prefabricated grow tents available. They set up and break down quickly, which is nice if you have to move in a hurry, and their setup is quiet, which means no loud power tools or noisy movement of building materials into your place.
For yields, you get six sides of highly light-reflective, and waterproof material that zips up to provide total darkness during the night cycle. People really short on space have been able to set up a grow right in their own bedroom with little intrusion, especially if they set the light timer to coincide with their own personal schedule.
You usually have two choices in terms of covering material when selecting your grow tent: white or textured silver. Most growers go with the textured silver.
There are also a number of grow boxes on the market. Many are light-tight and designed to look like filing cabinets or storage units for the ultimate in stealth. These are great for a garage or fit nicely into an extra bedroom.
Download this magazine now: