Because Hydroponic substrates are inert (devoid of food), the food is provided to the plant through a balanced diet of liquid nutrition (nutrient), which is added to water in the nutrient tank/reservoir. This is then fed to the plants, ensuring that they are getting adequate levels of food.


Plant nutrition is a complex business. How each element affects the plant, whether the element is mobile or immobile within the plant and the interaction of each element with other elements along with their part in photosynthesis is always going to be a complex business to discuss.


Fortunately, it is something that the indoor grower doesn’t have to worry too much about today as there are many good nutrients on the market. They differ somewhat in their macro and microbalances; however, using a reputable brand should ensure that the plant is receiving the correct balance of macro and micro nutrition.


Often individuals will ask me to recommend a brand of nutrient over the other brands. I’m going to tell you the same thing as I tell them regarding this. “I really could not tell you. If I were to put 100 hydroponic gardeners in the same room there would be a raging debate about the best nutrient to use” (among other things).


What I am saying here is that personal preference and your growing practices (recycling v. run-to-waste, nutrient tank/reservoir practices etc.) will determine the best nutrient for you. I would be extremely hesitant to recommend any one brand over another. There are many, many good nutrients on the market today.


Nutrients can be purchased as single part formulas, two part formulas and as triple pack formulas. Over the years I have played with all of these systems and achieved great results across the board. Again, personal preference (ease of use etc) will help you decide which is the most ideal for you.


My only recommendation…. the thing about nutrients that you ought to be aware of is the hype that goes with them. Be wary of paying too much for a product that probably isn’t going to perform any better than the product next to it that is 30 – 40% cheaper. You may be paying extra for an extravagant label, importation costs, and the manufacturer’s advertising campaign.


I’ve had some of the expensive brand names lab analysed only to discover that they aren’t anything special compared to far cheaper brands. If you factor in the vast number of different growing methodologies practiced amongst indoor hydroponic gardeners and if you understand what goes into a nutrient, the approximate cost of the constituents, the principles of plant nutrition and particularly the principles of the sufficiency and luxury nutrient ranges, which I discuss in detail later in the book you tend to be a bit sceptical about using higher priced products. For example, here is what a highly renowned PhD biochemist and plant nutrient expert had to say after analysing perhaps the most expensive (given nutrient concentration and price) big name multinational brand on the market today.






There is nothing unusual or unexpected in the mixes. Veg is a fairly standard grow mix and Flower is a fairly standard bloom mix. Both are rather more acid­ic than optimal, due to the formulation used. Flower B contains much more ammonium than most other plant nutrients. This is because monoammonium phosphate is used to boost P to the high levels required. The following formulations will provide a solution which is close to those supplied. You can never be exact, because batch-to-batch variation between fertilizers means you will never get better than 98% reproducibility.”


(End Quote)


The hydroponic store I worked in at that time was one of the top 10 Australian distributors of the line. After a falling out with its Australian distributor we had the products (nutrients and additives) lab analyzed and subsequently reverse engineered them.


What we immediately did was drop the price from a rather hefty $99.00 AUD for a 2 part 10ltr A&B set for the original, reducing it to $50 AUD for our product which was presented in unlabeled plain white bottles with A and B written on them in black or blue permanent marker (very high tech and truly a nutrient without the bells and whistles!). Not only this, but there was no impressive laboratory or white coats anywhere in sight – our product was knocked up by the biochemist in 200ltr plastic drums using a water pump to circulate the ingredients as he mixed.


We then told our customers that we were dropping their preferred line (largely preferred because we had recommended it in the first place) and that we had engaged a highly renowned PhD Biochemist to reverse engineer and “tweak” the original formulas and that the copy was as good as the original – if not better. We, however, added that if they didn’t find our nutrient to their liking we would order the original for them as they required.


As it turned out the product was a hit. Our PhD biochemist had weaved his magic and not only were our customers confirming the new products quality but also, in many cases, stating (insisting) that it was superior to the original, producing higher yields and a better quality end product. I myself, on trialing the product, was happy but didn’t see any differences in yields and/or quality, when compared to the original, and put my customers rave reviews down to a collective hysteria… a placebo effect based on savings. Nevertheless, the bottom line; not one single customer (not one) requested the original again and new customers began appearing at the store seeking our no thrills, cheaper product that they had heard so much about through their friends. Within weeks, the product was walking out the door and our customer base increased by approximately 20% within the year. No small feat given two new stores had opened within 10km of us in approximately the same period.


The moral of the story: The power of branding and marketing.


Were the original formulas any better than any other formula? Clearly many growers thought so. The company is multinational with a good reputation – one that it has worked hard to create – and certainly their nutrients are better than some formulas I have subsequently lab analyzed. On the other hand, as the biochemist noted, there was nothing “unusual or unexpected” about their mixes. Good formulas pretty much tend to look and perform about the same and the key difference – if any – comes down to marketing and consumer perception.


Why then did our store recommend the multinational product over others?


In truth, because it was a product I had used and liked (better than some – no better than others) and secondly, perhaps more importantly, due to its higher recommended retail price we made more profit from selling this product over cheaper brands. It is important to understand this factor and it is true of all retail businesses, whether they be selling clothing or hydroponic specialty equipment. In short, hydroponic retailers, by retail standards, have low profit margins on the goods that they sell; typically about 60 -100% markup on wholesale price where consumables (e.g. nutrients and additives) are concerned and even lower margins, in many cases, on hardware. Think yourself lucky on this front. For instance, to generalize somewhat, clothing retailers typically markup 200- 400% (or even more). Basically though, if you purchase a $100 10L nutrient pack the retailer has made about $50.00. On the other hand, if you purchase a $50.00 10L nutrient pack the retailer has made $25.00. If you were him/her and had a business to run, with all of the associated costs (e.g. rent, insurance, wages, superannuation), which product would you prefer to sell? It’s a case of simple business economics. Other than this, some nutrient manufacturers fully understand this principle as good business practice. I.e. create products that create higher profit margins for the retailer and they are likely to support it. For example, the company’s whose formulas we reverse engineered and sold to our customers was found guilty of price fixing in Australia in 2005 by an Australian Government corporate watchdog. The Australian distributor of this product had sent an Australia wide letter to retailers demanding that they stop discounting their brand below the ‘recommended retail price’ (RRP) or they wouldn’t supply them. This, as it turned out, was in breach in corporate law and as a result the company was called to task.


When discussing value for money, with regards to hydroponic nutrients, it is important to note that some nutrient brands are more mineral dense (concentrated) than others, meaning that some nutrients require a lower dilution rate than others to achieve the same EC in solution. Therefore, when considering the price/value of a nutrient be sure to factor in the product’s concentration.  That is, if one product is 40% more concentrated than another and costs 25% more, this product is actually 15% cheaper than its less concentrated counterpart because it will go 40% further at only 25% more recommended retail price.


Okay, that was pretty simple, wasn’t it? Now I’m going to get somewhat technical and explain what roles the different macro and microelements play in the plant.


Before I do this, I had better point out that there are some nutrient deficiency symptoms outlined. However, it is important to note that while visual nutrient deficiency symptoms can be a very powerful diagnostic tool for evaluating the nutrient status of plants, one should keep in mind that an individual visual symptom is seldomly sufficient to make a definitive diagnosis of a plant’s nutrient status. Many of the classic deficiency symptoms such as chlorosis and necrosis are characteristically associated with more than one mineral deficiency. Additionally, what appears to be a nutrient deficiency can be due stresses’ such as high ambient air temperatures, pathogens, high levels of sodium chloride in solution or the substrate, oxygen starvation in the root zone (due to too high temperatures in the nutrient and/or substrate) or air pollution etc. Often, symptoms of these stresses closely resemble those of a nutrient deficiency. That is….


Some possible reasons for nutrient deficiency and excess symptoms beyond actual nutrient deficiencies and excesses:


1) The mains (municipal) water supply that you use may be high in microelements such as iron, copper and zinc. When these combine with the microelements in the nutrient solution toxicity is expressed due to too high levels of micro-nutrition in the nutrient working solution (I.e. the solution that is being fed to the plants).

2) Your mains water supply may contain high levels of both sodium and chloride. When combined this equates to high levels of common table salt (i.e. sodium chloride or NaCl) in solution. High levels of NaCl is toxic (phytotoxic) to plants and is expressed in what looks like nutrient deficiencies and/or excesses.

3) If growing in coco coir substrate, did you purchase a quality flushed and buffered coir substrate or a cheap compressed brick product? Similar to some mains water supplies, cheap coco coir products can come loaded in sodium chloride. The end result is phytotoxicty and what looks like nutrient deficiencies and/or excesses.

4) Plant Pathogens often produce an interveinal chlorosis in the leaves (yellowing or whitening of the leaf veins) that can be easily mistaken for a nutrient deficiency. Put simply, when a pathogen infects a plant, it alters the plant’s physiology, particularly with regard to mineral nutrient uptake, assimilation, translocation, and utilization. Plant pathogens/diseases can also infect the plant’s vascular system and impair nutrient or water translocation. Such infections can cause root starvation, wilting, and plant decline or death. Plant pathogen/disease symptoms can often be separated from nutritional symptoms by the rate in which they affect a population of plants. If the plants are under nutrient stress, all plants tend to develop similar symptoms at the same time. However, if the stress is the result of pathogens, the development of symptoms will have a tendency to vary between plants.

5) Too high ambient air temperatures (heat stress) severely limits utilization of absorbed light energy in photosynthesis which leads to exposure of the chloroplasts to excess energy and thus generation of reactive oxygen species (ROS) such as superoxide radical, hydrogen peroxide, hydroxyl radical and single oxygen. Therefore, oxidative cell damage is a common phenomenon in heat stressed plants.[1] The end result is what looks like nutrient deficiencies and/or excesses.

6) Excessive humidity slows transpiration in plants which results in slowing the distribution of nutrients throughout the plant. The end result is nutrient deficiencies.

7) Oxygen starvation in the root zone results in an unhealthy root system and thereby can greatly impact on nutrient uptake, resulting in deficiencies. In hydroponics, oxygen starvation in the root zone due to overly warm nutrient and/or media temperatures is probably the leading cause of root death and reduced growth rates. I.e. unhealthy roots = unhealthy nutrient uptake and, as result, nutrient deficiencies occur.

8) Salt buildup in the media and root zone can cause damage to the plants both through direct contact with the salt crystals around the plant stem, particularly in young plants, and by increasing the osmotic pressure around the roots. The end result is nutrient deficiencies.

9) pH problems are often the cause of nutrient deficiencies because pH determines the availability of mineral elements to plants. Too high or too low pH can, therefore, reduce nutrient availability resulting in deficiencies.


As you can perhaps see, nutrient deficiency or excess symptoms can be caused by numerous biotic and abiotic stresses. Therefore, any deficiencies and/or excesses need to be addressed holistically because often what appears to be deficiencies or excesses are caused by unfavorable environmental conditions, pathogens and/or root disease. As such, it is too simplistic to label the problem as a nutrient deficiency and/or excess before covering all of the bases. That is, if you plants show signs of nutrient deficiencies or excesses check that the roots are healthy and white (not turning brown).


Check that your environmental conditions are within ideal parameters (temp, airflow, humidity etc).


Check that your pH and EC meters are calibrated and working properly (a trip to the hydro store to have your retailer look them over may be in order).


Check for signs of salt buildup in the media (if in doubt flush the media with pH adjusted water). And, treat your plants for potential pathogens (speak to your retailer for more information about product options). Last, but by no means least, dump and clean your nutrient tank and mix a fresh batch of nutrient to cover all bases. Other than this, a foliar feed or two will greatly help the plants recover from a deficiency. After you have implemented all of these measures, watch the plants closely to make sure that the problem starts to clear up over a few days. Old growth may not recover, but new growth should appear healthy.


Steps to follow where a nutrient deficiency is apparent


  • Check the roots of the plants. Are they white (healthy) or brown (unhealthy)? If the roots are brown check your nutrient tank/reservoir solution temperature – it should be below 23oC (73.4oF) – the ideal range being about 20 – 22oC (68 – 71.6oF)
  • Dump and clean the nutrient tank/reservoir and mix a fresh batch of nutrient
  • Flush the media with pH adjusted water (salt build up and or a nutrient excess may be locking out crucial nutrients)
  • Treat the plants for potential pathogens
  • Check that all of your grow room environmental factors (air tamp, water temp, relative humidity) are within ideal parameters
  • Foliar feed the plants as a quick fix to correct a deficiency (avoid in mid to late flower due to the potential for botrytis/grey mold and/or powdery mildew etc)
  • Ensure that your pH and EC are within ideal ranges after you have made a fresh batch of nutrients
  • If in doubt about the reliability of your pH and/or EC readings take your meters to your hydroponic retailer to have them looked at (this is recommended either way)


It is important to note that by the time you identify symptoms of nutrient deficiencies or excesses the problem has already impacted on yields (this is particularly true during the bloom cycle). I.e. a plant’s growth rates are reduced long before deficiencies or excesses become visually apparent.  Scientists call this phenomenon “hidden hunger” (nutrient deficiency) or “incipient toxicity” (nutrient excess).


We’ll be covering more on nutrient science later which will help you to understand the principles of hidden hunger and incipient toxicity. However, briefly for now, let’s begin with incipient toxicity, where a nutrient excess is present.


As the name implies, incipient toxicity describes being in an initial stage; “beginning to happen or develop”. Therefore, incipient toxicity is where excess nutrients slowly begin to accumulate in the plant tissue to such a degree that they start to become toxic.  Signs of excess won’t necessarily become apparent for some time. However, growth will be impaired long before nutrient excess signs become apparent. Therefore, while growers are providing too much nutrient (enough nutrients to impair growth) they can be completely unaware of this because the visual symptoms that growers attribute to excess aren’t apparent. Nevertheless they are losing yield because this excess is hidden and is impacting on growth.


Where “hidden hunger” (nutrient deficiency) is concerned, as the name implies, the plant is hungry but we cannot see it (i.e. symptoms of hunger are “hidden”). Because the exact concentration of a nutrient below which yields decline is difficult to determine precisely, some experts define the critical level as the nutrient concentration at 90 or 95% of maximum yield. However, hidden hunger can be present well before this without visible signs of a deficiency.  For example, a grower may only be achieving 80-85% of the maximum possible growth/yield before visual symptoms of a deficiency present.


In fact, scientifically speaking, the expression of nutrient deficiency symptoms varies for acute or chronic deficiency conditions. Acute deficiency occurs when a nutrient is suddenly no longer available to a rapidly growing plant. Chronic deficiency occurs when there is a limited but continuous supply of a nutrient, at a rate that is insufficient to meet the growth demands of the plant.


Most of the classic deficiency symptoms described in textbooks or online are characteristic of acute deficiencies. However, the most common symptoms of low-grade, chronic deficiencies are a tendency towards darker green leaves and stunted or slow growth. So basically, where a chronic deficiency is present, the plants leaves are dark green. As such, the plant looks healthy to novice growers (if it’s dark green its healthy right?). The problem is that dependent on the degree of a chronic deficiency many novice growers are unlikely to be able to spot that growth rates are less than optimal. From a scientific perspective, the only way of knowing that hidden hunger or a chronic deficiency is present is through lab analyzing the plant tissue or through having another plant that is being fed with more ideal nutrition to measure growth rates against.


This is something that hydro nutrient manufacturers and others typically forget to mention. That is, many ‘hydro’ growers have been led to believe that if a nutrient deficiency or excess is present then the plant will tell them this through displaying symptoms of excess or deficiency.


Nothing could be further from the truth!


The fact is that yield losses can occur long before signs of excess or deficiency become apparent.



[1] Yamashita et al. 2008; Suzuki et al. 2012; Marutani et al 2012