Pretty sure this is often goggled upon, and often end up with either too many irrelevant or no results. Simply, we are mostly busy with browsing for more species to add to our collection rather than spending time understanding how to grow them to their fullest potential. With the assistance from social media influencers and the pretty well timed pandemic in a bad way, the plant craze have amplified globally to such a big scale that is is definitely here to stay for long.
So what is the perfect blend of fertilizer solely meant for aroids? Is there such a holy grail bag of miraculous stuff that they need? Yes! Its your all in one multi purpose garden soil! Amidst giving the most natural, balanced nutrients to your plants, they poses some fundamental moisture retaining issues that leads to root rot, number one killer of aroids. Though it can be overcome by providing chunky airy substrates to the mix, soil is often disregarded by most. Now the very serious irony in this era of technology is that we get driven by the monkey see, monkey do approach; if some reputable social media influencer says soil is no good, its no good. soil-less is good, its good. Period. Don't get me wrong, its through much experiences from them personally, and we have them to thank for exploring alternative potting media alongside add-on fertilizers to compliment the entire setup. Lots can be discuss on the different types of potting media here as well.
There is a very important need to understand the basics of what nutrients do plant needs here. Much to disbelief, there is actually a very big gap of understanding on the food we feed our precious plants with in the community, and very much driven yet again by entities of influences on fertilizer we are using vs fertilizer we ought to use for our lovely foliages.
Before we even begin, I would like to point out the very important facts that what most of us are doing wrong unconsciously.
Giving too much - just a brief introduction to the terms commonly used in science in the world of plant food. Critical levels/limits and sufficiency ranges are the measurements of individual nutrient elements required for different species of plants, often expressed as parts per millions(mg/L). Experiments of such are often conducted by universities throughout the world and you can often find and read their research papers(yes we do) published. In general, every different family of plants have different requirements, having too much can actually lead to toxicity and often lead to the death of the plant, or nutrient antagonism, in which leads to perceived nutrient deficiency syndromes and stunt growths. and if you just skip the above basics, please do try to read again here else it really wouldn't make any good sense for you.
Here you see the very stripped down version of a mulder's chart. And to ease the understanding for most, lets just zoom into the relationship for just the 3 macronutrients NPK. High N antagonize K. High P antagonize K. Simply, on a layman point of view, having equal ratios of NPK may/may not be good at all. Lets do two case studies:
a) crop of edibles grown on soil, supplemented with NPK 15:15:15 slow release fertilizer good? Definitely. With a fundamental laying of organic nutrients readily made available via soil, the synthetic fertilizer acts as a supplement to the crops overtime.
b) pot of philodendron potted in soil-less potting mix of coco chips, wood barks, perlites, pumices, with controlled released fertilizer osmocote NPK 15:15:15 as the only source. No way! More likely than not, signs of nutrient deficiency though the lack of important nutrients, as well as nutrient antagonism will show overtime.
Furthermore, as mentioned earlier, different plant species requires different nutrients and edibles tend to need high potassium, and aroid tends to need high nitrogen. Golden rule of thumb for foliage plants are often NPK 3:1:2. do a search online and you shall find=).
Giving too little - now, referencing to 2 paragraphs above, plants require all necessary elements to function as a plant like humans do. Anything lesser will almost guarantee shutdown. Similarly, unless you are in soil, you almost definitely are required to provide supplements on top of equal ratio-ed general synthetic fertilizers simply because they are lacking or not present at all. Of course, depending on where you resides, the water source does provide some of the elements required through your water regime. not to bore you down with the list here for Singapore's water quality/content, below is the summary of what is enough and what is not. Do remember this is a general referencing towards the requirements of Aroids in particular.
Nitrogen(N) - Present but lacking in huge amount
Phosphorus(P) - Present but lacking in huge amount
Potassium(K) - Present but lacking in huge amount
Calcium(Ca) - Present but not sufficient along with constant fluctuation
Magnesium(Mg) - Present but not sufficient
Sulphur(S) - Present sufficiently
Iron(Fe) - Present but not sufficient
Manganese(Mn) - Present but not sufficient
Boron(B) - Present but not sufficient
Copper(Cu) - Present but not sufficient
Molybdenum(Mo) - Present but not sufficient
Zinc(Zn) - Not present
In the entire list above, only Sulphur meets the criteria, whereas there is a certain degree of lacking in individual elements. That explains why Sulphur is typically not stated anywhere in the analysis of local fertilizers we bought? To bring you to real life encounters; ever have some plant that is always thriving, dishing out majestic leaves consistently and all of a sudden your plant came into distress, yellowing of old leaves, blackening tip of young shoots, withering in general, you approach the gurus on online communities asking for answers as to why it happen, and all the responses you get is over watered, under watered, not enough lights, check for root rots, check for pests, facing wrong window, potting media is not airy, not enough humidity and the list goes on and on, and the mystery is never solve. Point is, why isn't there a shout out on what fertilizers are you using, and what potential elements is your plant lacking on? On a fair note, all stated above are very much based on science and data, much fairer as spoken initially, are we are really too busy adding new collections than taking care of existing ones?
Would definitely want to emphasize on this point: most plant will and shall thrive even with a general equal NPK ratio fertilizers overtime. The lacking of certain elements may not bring demise to a plant immediately but will definitely and progressively bring malnutrition overtime as when they grow larger, their requirements gets higher.
An example shown on the left is an Alocasia Frydek purchased through Sindo in Dec 2020. All is good until repotting with a mainstream slow released fertilizer a month later with NPK ratio : 13-11-11 + trace elements. Frydek shows signs of growth for 2 months before nutrient deficiency can be shown on the leaf (fading/yellowing of leaf edges), before withering off gradually. This continuous growing of 1 new leaf with nutrient deficiency and withering of the older leaf progress and growth of Frydek is stagnant until another repotting with newly introduced controlled released fertilizer with NPK ratio of 3:1:2 with calcium and magnesium alongside all trace elements. Photo shows a complete velvety and green leaf(newest). Will update in few months time.
We would also like to bring to your attention that these are all purely based on experiences accumulated, as well as tons of evidential science based on researching to understand the need of our beloved plants. Afterall, being a plant collector, we want what's best for them. At Ember and Leaf, we do know it, because we grow too. Should you come with alignment with science, and would want to provide for them, do it right the first time and everytime, do check out our Aroid Essence series here.