By Danny Danko and Erik Biksa
Welcome to the 2013 High Times Hydro Report. Let’s start by defining “hydro” -- a term that gets thrown around a lot by growers, though it may mean different things to different people. Strictly speaking, “hydroponics” means growing plants without using soil as the medium. That covers a lot of different setups, from using a soilless medium such as rockwool to hold the roots in place to actually having the roots suspended in air with only an oxygen-rich nutrient mist to feed them.
This creates a wide variety of growing possibilities. Hence the popularity of soil-less gardens -- those gardens that take advantage of purely hydroponic principles while tempering them with the flexibility and forgiveness we more commonly associate with soil gardens. The mediums in such gardens include coco coir, peat mixes, rockwool and more. Basically, although a growing medium is used, it’s relatively “inert” or low in naturally occurring bio-activity. With this kind of hydro growing, we use soilless mediums to create the perfect sponge for holding oxygen, water and nutrients to produce serious yields of frosty buds.
Why Go Hydro?
Plants grown hydroponically exhibit explosive growth rates when all the factors are properly in place. Although hydro growing is less forgiving than soil, it’s more rewarding when done right. The grower must ensure that light, nutrient solution, carbon dioxide and oxygen are present in the proper amounts at all times or else the system breaks down quickly, resulting in slowed growth and even death for your plants. However, growers with more of a technical background and less “green thumb” farming experience love hydroponics for the fact that it’s easy to monitor and results in plants can practically be seen exploding with growth before your very eyes.
There is also less risk of pests when growing hydroponically. Many pests and pathogens are brought into a growroom via the soil, which also provides a perfect place for these pests to hide and breed. Hydroponic growers can still experience infestations, of course, but they are less likely and easier to spot in a clean soilless situation.
Types of Hydroponic Systems
Ebb-and-Flow (or Flood-and-Drain): In this type of system, plants in trays or on tables are periodically fed nutrient solution from a reservoir beneath the garden. The solution then empties back into the reservoir for future feedings. Popular mediums for holding the roots in these systems include expanded clay pellets (grow rocks) and rock- wool cubes or slabs.
Nutrient Film Technique (NFT):
When using an NFT system, a constant shallow “river” of nutrient solution flows through tubes, feeding the roots as they dangle down from net pots. Because there’s a constant supply of water touching the roots, it’s very important to ensure that enough oxygen is present in the nutrient-fortified water.
Drip irrigation employs tubing that feeds each plant individually by slowly but almost constantly releasing droplets of nutrient solution through drip emitters placed at the base of each plant. A pump on a timer periodically sends liquid plant food through a manifold that then uses spaghetti tubes to deliver the nutrient solution.
Deep Water Culture (DWC):
DWC systems incorporate individual buckets for each plant, sometimes regulated by a main feeder bucket and sometimes as standalone containers. The roots dangle down into oxygenated nutrient solution and grow extremely quickly as a result, supporting monster plants up above when all of the other factors are at optimum levels.
Aeroponic growers take the hydro concept to the extreme by using misters to spray roots as they’re suspended in midair. This method of feeding promotes rapid root and plant growth, but it’s also prone to disaster if the misters clog or pumps fail. Consider using aeroponic techniques only once you’ve mastered the other aspects of soilless horticulture.
Essential Items for the Hydroponic Gardener:
PH meter plus PH up and PH down
Nutrients for vegetative and flowering growth
Air pump and air stones for reservoir
Water pump for reservoir
Thermometer for reservoir
Chiller and heater for reservoir
Hydroponic Reservoir Maintenance
Below most hydroponic systems sits the reservoir, where the nutrient solution is stored for watering purposes. The solution must be drained and replaced with fresh water and nutrients every two weeks minimum. Also, never allow light to reach your reservoir, as water plus light equals algae and molds (so always use an opaque lid).
Ideally, the PH level of the solution must be kept between 5.5 and 6.2 at all times. Adding nutrients and supplements can change the PH level drastically, and it can also change over time as the solution sits. The PPM level of the nutrient solution -- a measure of its electrical conductivity (EC) or total dissolved solids (TDS) -- is generally best between 800 and 1,400 ppm, depending on the strain and stage of plant growth. The PPM can also change as the water evaporates or is taken in by the plants.
Water temperature must not exceed 80F or drop below 65F or else the plants will quickly stop growing and possibly die. Regulating it is achieved with a simple aquarium heater to raise the temps and a more complicated (and expensive) chiller system to lower them.
Maintaining the proper temperature is absolutely essential to success in hydroponic applications, since veering outside the permitted range has claimed many a hydro grower’s garden.
As the days go by, the level of nutrient solution in your reservoir will inevitably go down. Replenish it with fresh, mild nutrient solution and then check the PH and PPM immediately. Never allow the solution level to go below half the size of your reservoir container. This means you could end up adding water or nutrient solution almost every day when growth is at its highest rate.
Last but not least, oxygenation is crucial. A simple air pump and air stone in the bottom of the reservoir will help -- but it’s nearly impossible to over-oxygenate a solution, so the more the merrier, since a nutrient solution that bubbles all over the place (as opposed to just in one little area of the tub) is far more effective in delivering essential oxygen to the roots. The equipment you’ll need to achieve this is cheap and readily available at any aquarium supply shop.
Organic or Synthetic Nutrients
Hydroponic growers seeking to use organic nutrients tend to run into several problems. Because the nutrient solution typically sits in the reservoir for two weeks at a time, organic nutrients tend to break down and start stinking or else assist in developing slime or molds. Plus organic nutes are particularly tough to use with individual drip systems, as they tend to clog the drippers or sprayers.
Most synthetic nutrients will stay fairly stable for the two-week period, and they also flow nicely through tubes due to their small molecule sizes. They tend to dissolve in water better and have the added benefit of not inviting pests in the way that some naturally formulated nutrients can. We recommend going the synthetic route for most hydroponic applications.
Using a Soilless Mix
With a high-quality peat- or coco-based soilless mix, just about anybody can grow a good yield of equally high-quality cannabis without a whole lot of hassle (and while keeping the costs of production lower). All you have to do is keep in mind some of the important principles involved, as well as the best way to take advantage of them and achieve the results you crave.
Sourcing Your Medium
There are several factors to consider when choosing the soilless medium that best suits your particular growing situation. Luckily, there are usually plenty of options, especially at a well-stocked hydroponic supply store -- but even the big-box stores or major garden centers may have what you need.
Fortified vs. Unfortified
The less fortified or precharged the medium is with nutrients or soil conditioners, the more “hydroponic” it is. That’s why you should avoid heavily pre-fertilized mediums for maximum control over your plants’ nutrition. If you’re the plant-and-run type, your hydro shop may have some good “just add water” mediums that have all the necessary nutrients to feed your plants for a month or two.
However, heavily fortified mediums are better suited to soil growing than they are to hydro. You can use either or both hydroponic and organic nutrients with good success in most soil- less mediums.
Faster-draining mediums provide more air to the roots, but they also mean you need to water more frequently. Some experienced growers prefer faster-draining mediums because they can “push” their plants forward a bit with more frequent and precise crop feedings.
Source of Parent Material
Organic materials such as peat that have been decomposed for thousands of years are typically more stable than, for example, younger mediums like coco that may be less than a year old. As such, the latter may still be undergoing chemical decomposition and other changes, which can jerk the nutrient and PH levels all across the board. If you opt for a coco- based medium (which is more enviro-friendly), make sure that it comes highly recommended and that you understand some of the differences when it comes to feeding crops in coco.
Straight or All Mixed Up?
Most professional mixes are good to grow straight out of the bag, but others can require some fortification for nutrients or buffering for PH. Adding a cup or so of dolomite lime to commercial peat mixes is a common practice for providing long-term buffering, especially with stronger crop feedings.
In most low- or no-fertilizer pre-charge mixes, adding high-quality earthworm castings can improve growth rates, crop health and yields when mixed with some extra perlite or pumice (for better drainage) into the commercial peat- or coco-based mix. Some growers love the buds they get when they mix coco and commercial peat in a ratio of 1:4 (the coco helps make the medium more “spongy”).
To Bed or Bucket?
What to put the soilless mix in? The rule here is that, where space allows, deeper is better. When cannabis plants don’t sense space limitations in their root environment, they show their appreciation by producing bigger root systems and more and larger buds. This makes a good case for beds or deep planters.
However, when space is tight, containers help keep plants within the size you can allot to them. Cold, damp roots don’t fare well in either soil or hydro, so a sheet or even Styrofoam peanuts can help keep roots from direct contact with cold floors and even assist drainage. The rule of thumb is to allow for at least one gallon of container size for every month of growth the plant will have before harvest. That’s the recommended minimum, but potting up to bigger and bigger pots is the preferred way to go, or else directly into raised beds or planter boxes.
Here’s another tip: Good drainage is crucial. You’ll want to apply more water or nutrient solution than you need just to wet the soilless medium. You’ll want to see some runoff, which helps to prevent fertilizers from building up to toxic levels over time, damaging yields and quality.
The initial wetting after transplanting your clones or seedlings is important. Here you want to ensure a “good stick” between the rootball and its new environment. Getting it right will result in a flawless transition and an explosion of healthy growth; too much water and plants will have a slow start. Worse yet, if there isn’t good contact with the roots to the new medium (i.e., not enough water), plants may dry up and suffer. A mild nutrient feeding with B-vitamins and a root inoculant -- for example, one containing mycorrhizae -- is a great way to start.
Humic and fulvic acid help to improve the natural properties of any growing medium, especially soilless mixes. If they’re not already supplied by your favorite nutrient additives, it’s recommended that you include them. Molasses can also help to stimulate strong microbiology, but it’s easily over-applied and may contribute to root rot quickly in warm, wet growing conditions.
Management and Maintenance
For the best results, view the life of your growing medium as a marathon rather than a sprint. If you apply all of your nutrients at the front end, your plants will still be choking or starving by the time they approach the finish line.
Salt buildup and overfeeding need to be avoided, but this takes some consideration and care as to how and when to apply your nutrients. If you garden without carbon dioxide (CO2), it would be rare to feed your plants nutrients past 1,400 ppm (2.0) EC during the bloom phase, and above 1,000 ppm (1.4 EC) in the vegetative-growth phase. Applying your fertilizer at quarter rather than full strength every third feeding or so to the point of runoff can help keep fertilizer residues from building up in the medium. If you grow big plants and enrich the environment with CO2, your crop will usually need more water as well as nutrients to keep up with higher metabolic activity that results.
Hand-watering is always the preferred method, but soilless gardens can easily be automated with a reservoir, pumps, timer and delivery lines. Note that fertilizer labels usually give the recommended doses at the higher end; start with half the recommended strength and work your way up from there if you don’t have electronic measuring equipment.
Save Your Medium and Keep Your Yields
Flushing with plain water or a very mild nutrient solution for the final two weeks before you anticipate harvest not only helps to improve the quality of your bud; it also allows you to successfully reuse your growing medium. This saves on lugging copious amounts of medium in and out of your grow facility, and it may even promote bigger and healthier plants as a beneficial microbiology develops over time. Using digestive enzymes and humates is a great way to break down old roots and buffer fertilizer residues. Adding some more perlite, earthworm castings and dolomite lime is another worthwhile step in getting your medium ready for reuse.
Proven Growing Tips for Soilless Gardens
Some strains like it if you let the medium dry out a bit between waterings, while others don’t. Experiment a little to achieve the best results over time.
If your medium becomes too acidic, one cup of hydrated lime in a full 55-gallon drum of water will raise the pH of the peat mix it’s watered into by approximately 1.0.
Don’t allow the roots to rest in standing water for prolonged periods of time; root rot may occur.
All of that growing medium can hold a lot of water. Make sure the weight is well supported if you’re using benches, and be prepared to regulate humidity levels as the water evaporates.
Keeping the top of the growing medium moist for prolonged periods will attract fungus, gnats and molds, so let the surface dry out between waterings.