Home made Fertilizers and their efficacy

[Ravi]

Tea bags hung over the plant producing a sustained release fertiliser.
Egg shells crushed and ground to powder.
Coffee dregs.
Used tea leaves
Bone meal traces to supplement Calcium and Phosphorus
Fish derived material traces.
The point is : do they really have a place or just kitchen ideas? How much these score over the conventional balanced NPK ? Aren’t they going to clog the root system and hasten the decay of the medium?

[MrHappyRotter]

A good, properly tailored "synthetic" standard NPK fertilizer is going to be leaps and bounds better and more effective than household organic waste. Good fertilizers include bioavailable versions of nutrients and trace minerals, in proper (known) strength and proportions, as well as buffered to appropriate and safe pH.

I think a lot of these kitchen waste / organic products are problematic for indoor growers (like me) because they can be malodorous, they can potentially end up providing food for pests like fungus gnats, some are potentially phytotoxic (coffee), they can significantly alter the pH of the potting media, and for the most part standard orchid mixes aren't conducive to the efficient break down of these products into useable nutrients, amongst other issues such as inconsistency, missing or disproportionate amounts of nutrients/mineral, etc.

I do sometimes use egg shells in my potting mix, but it's mostly a "just because" kind of thing. Most of the little pieces quickly fall out of chunky epiphytic potting mixes, and those that remain don't really break down. I've repotted plants that after 3 years the pieces of egg shell that remained in the mix looked basically the same as they did the day they went in.

I've used fish products, bone meal, and blood meal in the past, but stopped because the smell was so bad and they all allowed gnats to proliferate. I wouldn't risk using coffee grounds due to concerns about phytotoxicity.

I think if you wanted to use these products for orchids, your best bet would be to make a compost out of it and then perhaps make a tea from the compost which you then use on the orchids (sparingly). I'd say there are still risks with this approach, still lots of issues with consistency, proportions, etc and overall still not as effective as synthetic fertilizers.

[Ray]

Well-stated, Mr. Happy.

[Ravi]

Mr Happy
Thanx for the reply. How does a blood meal find a place in the orchid care ? Blood means Haemoglobin otherwords Iron along with the plasma proteins which on standing at RT -room temperature gets damaged and infected, no doubt it stinks.
Doubtful is an egg shell in its original form that it can provide Calcium , for any nutrient or mineral to be efficiently absorbed it has to be in its soluble form to be available at the target tissues. Egg shells at best can increase the porosity of the medium..
You are spot on in your views on NPK they are reliable in calibrated concentrations and predictable
Expanding further on this for any nutrient to find its way in to a bio system it has to be either water soluble or fat soluble.
Thanks again

[Ray]

The nutritional demands of pretty much all plants may contain the same elements (which happen to be pretty much the same in humans, as well), but the amounts and relative levels vary significantly. Plus, "too much" of something can be as bad, if not worse that "too little".

If you look at the tissue analysis (not particularly reliable, as it tells you what's present, not what is required) and that of the water cascading down onto epiphytes, you'll see that nitrogen is the big one ("big" being relative, as the total nutrient concentration is typically under 15-20 ppm in the throughfall), with P & K being less than 10% of the nitrogen concentration and everything else in trace amounts.

Also, be very aware that - as has been said - nutrition is very low in the priority of needs of orchids, and no amount of nutrient is going to fix other cultural issues.