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Lack of micronutrients in substrates can be effectively prevented

2. 2. 2013

Some growers keep having persistent problems with the quality of their produce – they are visible and often easily spotted even with an untrained eye. These problems lie in the lack of key biogenic elements such as N, P, K, Ca, Mg, S, but also in the lack of micronutrients, such as Fe, Mn, Zn, Cu, B, Mo, Ni, Co or Na, Al and Si.

These disorders are occurring more often as pure peat substrates are becoming more popular – these substrates don’t contain any clay and therefore cannot hold any nutrients, not to mention releasing them for the plants.

Experience and practice

Sometimes these obvious signs are underestimated and their cause is sought only in the physical qualities of the substrates; this leads to the over-rating of a coarse structure, which is based upon various theories about the content of air or dust particles.

However, analytical findings during laboratory examination of substrate samples tell a completely different story!

One of the main problems with these substrates is their pH. It is far from ideal. Sometimes it is too low, other times it is too high. Both extremes can significantly influence the solubility and admissibility of nutrients, no matter if it is small or extremely high, sometimes also called “luxurious”. This is not a mere theoretical statement, but a result based on analysing the samples taken directly from growing facilities all over the Czech Republic. AGRO CS has its own accredited laboratory No 1468 and so far performed several thousand of such analyses, which tells much more than just a random finding. Of course it is always necessary to seek, in a proper and unbiased way, the causes of such condition.

An easy solution

The primary goal is to eliminate the detected nutritive deficiency effectively and quickly. One of the possible solutions is Micromax Premium – a micronutrient concentrate. It is produced by EVERRIS (formerly SCOTTS).

Micromax Premium is a mix of micronutrients, which contains 15 % iron (sulphate form), 2.5 % manganese, 1.0 % zinc, 0.2 % boron, 1.0 % copper, 0.04 % molybdenum and 15 % magnesium (of the total content, 25 % is fast-admissible water-soluble form and 75 % slow-releasing magnesium). The composition makes it an ideal product for micro-nutrition of potted plants. The length of its action depends on technology and ranges between 16 and 18 months. The application is safe and there is no threat of damage to the plants. An optimum ratio of boron to zinc is very important due to antagonistic relations between B and Zn. Thanks to the sulphate form of iron the lack of micronutrients can be easily and effectively prevented so that iron is not washed away as it often is in its chelate forms. The fertilizer is therefore environment-friendly.

Unparalleled action

The unique action is a great advantage of this fertilizer. It lies in the product’s ability to release micronutrients in less-than-optimum growing conditions.

There are many cases when the quality of irrigation water is not considered, or when the length of cultivation becomes longer than the original estimate. These situations often lead to an increase in substrate’s pH, which is the moment when micronutrient problems start appearing. The characteristic signs include chlorosis of the plant tips caused by iron deficiency – the high pH blocks its absorption.

Acidophilous plants, on the other hand, may suffer from fast release of iron if the pH is too low (chelates easily leach out) and the iron becomes toxic. Acidophilous plants may also have problems with magnesium absorption, because its intake is significantly limited in an acidic environment.

The signs of magnesium deficiency are very similar to lack of iron – they are demonstrated as chlorosis, but the veins on the leaves remain dark. The standard fertilization with water-soluble fertilizers has no effect, because the combined fertilizer contains potassium as well.

Potassium acts as a significant antagonist of magnesium intake (it blocks it). A similar case occurs if soft rainwater is used for irrigation, especially water that is collected from covered roofs such as greenhouses or plastic hoods. This precipitated water contains no minerals and when it is combined with the substrate without any available calcium or magnesium, magnesium deficiency is a very likely result. In these situations, Micromax Premium works very well; it is a tested-and-tried argument for continuous nutrition of all your plants.

These are very important arguments that cannot be simply overlooked. Many substrate producers, Czech and foreign, sort out micro-deficiencies by using Radigen fertilizer. However, some of its weaker properties include less-than-perfect Boron to Zinc ratio, content of iron in chelate form, which often leaches out of the substrate quickly, and significantly lower content of magnesium. The shorter time of action is also a reason for serious consideration (only six months in greenhouse cultures).

Practical results of use

The results in practice are very convincing. Excellent growing results are achieved with plants such as Buxus, Calluna, Cytisus, Hebe, Hydrangea, Pieris, Vinca and other species. EVERRIS, as the producer, also presents the results of its company trials performed at Trialstation Knol testing stations in Eefde, Netherlands. There it is possible to see their cultivation experiment with Potentilla tridendata ‘Nuuk’ and Chamaecyparis lawsoniana ‘Columnaris’. In both cases it becomes clear that even if the pH is very high (7.0 and over) the use of Micromax Premium prevents the occurrence of chlorosis. Although the plants grow weaker with the high pH and do not show such a growth potential, they are not chlorotic like plants on other comparable fertilizers.


Just like in many other disciplines, economics plays a key role in plant growing. It may seem that a few plants with yellow leaves are not a catastrophe, but a closer analysis will tell you that only plants in perfect “A” quality have a good economic potential, and that customers will only buy flawless plants.

I do believe that many producers still grow plants for the love and joy that it brings, but the produce must sell at a reasonable price. Before starting to experiment with nutrition, consider the potential risks please.

You can never fail by using AGRO CS substrates with Micromax Premium as a standard component, because ours are always “successful growers’ substrates”.

Ing. Jiří Valtera, AGRO CS