Why grow hydroponically? While soil is forgiving for first-time growers and allows the use of a wide variety of fertilizers and supplements, including organics, the levels of dissolved oxygen at the roots of a plant grown in soil are relatively low compared to a well-planned hydroponics system. In soil, plants have to compete with other organisms in the rhizosphere (root zone), such as fungi and bacteria, to extract nutrients and other essential building blocks. While many microbes work symbiotically with the plants, assisting them in absorbing these materials, the fact is that plants grow fastest in a sterile root environment with plenty of oxygen. Pure and uninterrupted absorption of oxygen, water and minerals provide everything that a healthy plant craves with nobody else cutting into the chow line.
Hydroponic growing can also help to conserve water and allows for much higher yields in the same amount of space if not less. In some systems, the nutrient solution is rarely (or never) dumped during cropping, and in some instances, the “used” solution can be pumped to feed mineral-hungry plants outdoors - all of which can make hydroponics a lot friendlier to the environment as well. Additionally, hydroponic planting mediums that are chemically stable and inert, such as Expanded Clay Pebbles, can be reused many times, thereby lessening the environmental footprint created by the grower. For example, consider that peat bogs, which can take tens of thousands of years to develop, are stripped to supply "throw-away" soils that one replaces with every crop. The reuse of Expanded Clay Pebbles also means that less fuel is ultimately consumed for the in the long run for transporting (and frequent replacing) of your medium.
1: Benefits of a Sterile Environment
Maintaining a sterile environment can also have other advantages when cultivating medicinal crops, where there is a risk of microbial contamination in plants grown from the soil for patients with sensitivities. In hydroponics, there is no microbial life introduced from the medium (or potential pathogens and insects from other food sources) into the growing environment because the medium and method keep that environment sterile. So in addition to plants being able to grow faster in controlled, oxygen-rich conditions, we can see many of the other benefits: re-usability, the potential for water conservation and a higher chance of maintaining a pathogen-free environment.
Root temperature is a severe growth prohibiting factor overlooked even by seasoned growers in their quest for bigger yields. Every grower knows how important it is to maintain the right air temperature for better results, so why not pay attention to the roots too? In hydroponics, the root zone can be controlled with precision and not just in terms of temperature either.
2: Faster Growth Rates
For a lot of growers, especially those who follow the guidelines outlined here, using hydroponic techniques will lead to increased growth rates. That means harvesting in less time, which means shorter waiting periods between harvests and achieving more crops in a calendar year. And if you get serious about hydro, it can mean bigger yields every harvest too. But don’t jump into the deep end of the growing pool and expect to avoid making some splashes while you get your hydro routine fine-tuned throughout a couple of crops, especially if it’s your first time.
While hydroponic growing is a powerful tool, some fundamentals need to be followed for success. For heightened yields, it may take some practice. However, just by maintaining the basics you’re almost certain to see faster growth rates, more tidy and efficient cropping and potentially less time required in the garden especially if you aim to graduate to automated hydroponic growing eventually.
In other words, learn the essentials first, and you will see that growing with hydroponics doesn’t have to be complicated or even expensive. Just manage your crop, your budget and your expectations accordingly, and you’ll be sure to have some fun while sticking to these hydro fundamentals.
By definition, water is the growing medium in hydroponics. For practical purposes, if any new medium is used, it’s simply to anchor the plants and provide a contact for their roots with the nutrient solution. Here is the fundamental difference between soil growing and hydroponics: in the latter, the food for the plant is in the soil itself, but when plants are grown hydroponically, it has a more direct relationship with the fertilizers and supplements you provide. By the same token, while this relationship promises incredible crop-feeding power, it also makes hydroponics less forgiving than soil. In hydro, you can see changes in your plants within hours, while with dirt it can take days. Expanded Clay Pebbles are a real hydroponic medium because it doesn’t have any severe or buffering nutrient capacity. Coco coir and Rockwool are also excellent (and accessible) choices while providing some buffering and ion exchange.
Some hydroponic systems use no medium at all; plastic collars or baskets simply support the plants while the bare roots are bathed in an oxygen-rich nutrient solution or mist. Fast growth and no medium to replace can be enticing benefits for hydroponic growers.
4: Water Quality
You can grow hydroponically even with water of marginal quality. Still, for healthy crops with increased growth rates and yields, you’re going to want to use the best quality water possible. For a lot of serious hydroponic growers, this means adding a reverse osmosis (RO) filtration system to remove all impurities from the water that could affect the nutrient chemistry supplied in high-end fertilizers.
As a rule of thumb, if the untreated water doesn’t taste good to you, it probably won’t be useful to your plants. Sadly, some water supplies are toxic and shouldn’t be consumed by anyone, especially by plants for medical consumption. Also, there are “hard water” nutrient formulations available from some manufacturers of speciality hydroponic fertilizers. Typically, they will contain less Sulfur, Magnesium, Calcium and Iron than conventional hydro formulas.
5: Dissolved Oxygen
This is very likely where the magic of hydroponics resides, as dissolved oxygen (DO) levels are often the most overlooked factor in generating a higher degree of health, growth and yield. Plants with elevated DO levels at the root zone are less prone to cropping problems and can use nutrients more efficiently. When super aeration is applied to bare root systems ( for example in a Deep Water Culture (DWC) system at a rate of 1.5L per minute (LPM) of air supplied via high output aeration pumps and air stones) the amount of fertilizer used can be cut in half, or even by as much as 75%, versus conventional soil or soil-less growing methods.
Some growers may be astonished to learn that they can maintain giant plants with a scant 400 ppm nutrient concentration, simply because the plants will process the nutrients more efficiently with the super levels of oxygen available at the roots. Around 0.75 LPM of aeration is plenty, but around 1.5 LPM is when you really see things start to surge. This means you should cut back nutrient strength proportionately with the level of aeration versus standard growing methods (though keep in mind that amounts will vary from system to system and situation to situation).
However, poor aeration (especially when coupled with warmer temperatures) can spell disaster in a hydroponic system. Some plant varieties will be more prone to root rot than others, although it’s wise to take every precaution: anaerobic conditions can be your number one threat in hydro versus soil gardening. Besides pumping air into the solution, moving the solution through the air- i.e. the nutrient return splashes into a reservoir- is a highly effective way to introduce more oxygen into the solution and ultimately, to the roots of your crops. If you maintain a reservoir, adding a small circulation pump to keep the solution stirred (especially between applications, as with flood-and-drain set-ups) will help to improve growth rates and cut down on problems by making more DO available for the roots. In this respect, it’s much like an aquarium, where the fish need oxygen in the water.
6: Root-Zone Temperature
While worrying about air temperatures up top, a lot of growers overlook what influence temperature has at the root zone. Hydroponics affords a level of precise temperature and overall volume of solution that surrounds the roots. For example, if your grow room runs warmer than optimal, keeping the roots bathed in a highly oxygenated and chilled nutrient solution can provide the necessary balance for healthy growth. Plus it’s more efficient, in terms of electrical consumption, to keep the root zone a few degrees cooler with a reservoir chiller than it is to cool the entire growing area.
In nature, the soil stays an even, cool and comfortable temperature even when it’s sweltering up top at noon. The same principle applies here. The fact that colder water holds considerably more dissolved oxygen than warmer water is another big plus for having a reservoir chiller. At the same time, however, cold basement floors in the wintertime can hurt growth. If the root zone temperature stays below 18°C/65°F, nutrient uptake can become limited. So while you don’t want your plants’ roots to overexert themselves in the heat, you don’t want them to hibernate either. An aquarium heater can keep the reservoir temperature steady at whatever set point you desire during the colder months. Most growers find a reservoir temperature of 19°C/67°F to be optimal.
Tip: To promote brighter colours and firmer product at harvest, instead of trying to cool your whole grow room down, you can chill the plants at their roots. Colours become brighter, and flavours are enhanced in days instead of weeks when you chill your solution below 13°C/57°F during the final days of cropping before you harvest (during your flush period).
The main reason that the relationship between the plant and the nutrient solution is so direct in hydroponics is that there’s nothing to get in between the nutrients and the roots. Plants absorb nutrients at different rates depending on pH. Keep in mind that pH is a scale that runs from acidity, or low pH, to alkalinity, or high pH. In hydroponics, depending on the medium and the growth phase, the optimal pH is usually around 5.8.
In most hydro systems, growers will have to work at keeping the pH from climbing up past 6.3. This can be done via automation (doser pumps and monitors) or simply by taking measurements with a pH tester and adjusting the nutrient solution with either a speciality pH Up or pH Down product. For this reason, some nutrients are much better suited to hydroponics than others which a topic we’ll address in reason number 9: Hydroponic Nutrients.
8: E.C / TDS
Electro Conductivity (E.C) and Total Dissolved Solids (TDS) are the most common terms used when discussing the relative and measurable concentration of the hydroponic solution you’re feeding to your favourite plants. The concentration changes as the plants use up nutrients in the solution and when water is added. If the concentration is too weak, then the plants grow slowly and yield poorly. Too high of a concentration can be even worse by causing nutrient burn which can stunt growth and lower yields. Plants start off needing less food when young and reach their highest level of demand during the mid or peak flowering stage.
Even so, their feeding requirements (and thus the concentration of the nutrient solution) begin to taper off as the plants reach maturity, and usually only clean, pH balanced water is applied during the last three to five days before harvest in hydroponics. Flushing a hydro crop is a much quicker and easier process than flushing soil-grown plants.
9: Hydroponic Nutrients
In hydroponics, especially recirculating setups, using a mineral-based solution is recommended over organic solutions. Soil is the better place for organics, where ingredients can break down further with the help of microbes and be released through the roots for improved plant growth. In hydro, this would create a biological funk, because there is no soil to buffer this long term reaction.
Ideally, in a hydro setup, the root zone will remain sterile and the nutrients will be supplied in their most available forms, by way of minerals rather than biological ingredients. In doing so, you’ll see faster growth, healthier plants and more consistent results. Some new products in the hydroponic market place actually introduce a special type of chlorine-based molecule into the solution, helping to keep the roots sterile without causing any harm, as the chlorine molecule quickly and safely breaks down after it’s done the job. Simply add a little to your reservoir every few days and increase the dose in warmer growing conditions.
Can you think of another reason to grow hydroponically?
Comment below and we'll complete this as a Top 10 Reason to Grow Hydro list!
Information sourced from High Times February 2014 edition.