What is the best fertiliser NPK?

[confusedchemist]

Hey guys
If I am entirely honest I am an absolute novice when it comes to orchid growing, but I have always found it incredibly relaxing and during my phd I seem to have collected a great deal more! I appreciate the sensitivity of orchids but have found a lot of conflicting advice on fertiliser choice. I recently bought some insect frass from a local company, Agrigrub, to use on my allotment but when I was looking at the NPK, 3:1:4, I noted it was similar to an orchid mist I bought from the garden centre. Do you think I could use this fertiliser instead? I don't want to kill my orchids so felt better to ask. Also this fertiliser has high chitin content but I couldn't find any advice online on whether that was good or bad.
Thank you so much you wonderful people
Nevi xx

[SouthPark]

I just use this ----- "Yates Thrive Orchid Liquid Plant Food" --- N:P:K is 10:3:14

The directions says around 33 ml per 10 litres of water, which is around 3.3 ml per 1 litre of water.

I normally just put in half or even one-third of that..... like 1 ml per 1 litre of water.

An orchid is not a fast grower - unlike for example a papaya (or paw-paw) plant. So an orchid is not going to need relatively large dose of fertiliser.

If applying as a foliar (leaf) spray ----- could use if you want a 'continuous fine mist spray bottle' -- see 'ebay'. Don't spray in direct sunlight. Spray during a relatively cool part of the day.

You'll always come across somebody that will say that foliar sprays are probably useless. Well --- I use foliar sprays anyway.

Later ----- you can even get into calcium/magnesium application -- which can be sprayed too, or applied to roots (when watering normally). Can just follow the directions written for orchids. Or just do what a lot of people do ..... and use lighter dosage.

But ---- every once in a while, to avoid build-up of salts in the potting media and around the roots ..... heavy flush of the roots and media with regular water will be good.

[confusedchemist]

THANK YOU SO SO MUCH
what an angel!
That feed you use has very high nitrogen content which I wouldn't have expected as orchids are so slow growing? That is all amazing advice, I've heard great things about foliar mists, but they were all so expensive hence me hoping I could avoid buying one by making my own with the fertiliser I already had

[Ray]

A few things I've learned:

Nutrition is very low on an orchid's "Maslow's Hierarchy" of needs.

A little goes a long way, and applying a lot is detrimental and will not "fix" any other cultural issue.

The truly important nutrient elements are nitrogen, calcium, and magnesium; if your fertilizer contains any phosphorus, potassium, and the "micros", it's plenty, as the plant will absorb them and store them for later use.

Know and consider your irrigation water chemistry, including its contents in your thinking about what nutrients you're supplying.

The ratios of a fertilizer formula are relatively unimportant, but the concentration at which you apply it is. Orchids in nature rarely see solutions greater than about 15-20 ppm dissolved solids, so have evolved to handle that. Strong concentrations should be avoided.

In my opinion, foliar feeding is not a particularly good way to do it, not because orchids don't absorb nutrients that way, but because their anatomical structures (waxy, cuticle layers intended to reduce foliar water loss) can interfere with uptake, as well.

[peters]

I'd suggest listening to Ray's advice and highly recommend reading all the information on his site. It contains many GEMS of information he has distilled over many years of experience.

[Orchid Whisperer]

The 3:1:4 and 10:3:14 N:P:K ratios are very roughly the correct ratio. However, see notes below.

All plants use roughly equal N and K. Significantly less P. My orchid club includes a professional horticulturalist, he confirms this, and I have read this for years in nutritional research conducted with orchids. Ca and Mg and S are also important. For all nutrients the concentrations required are low. Since the concentrations needed are low, as long as a fertilizer contains N, P, and K, none missing, you are probably OK.

It is important to remember that all of the nutrients provided need to be soluble, available to be absorbed as the fertilizer solution passes over a root. The insect frass (bug manure) might be a good terrestrial plant fertilizer, but an orchid can't use N and P that are locked up in chitin, it is likely to wash through orchid medium before it breaks down enough to release much nutrition. There could be some fraction of the frass that is soluble, and could provide nutrients, but be careful not to develop a build up of frass in your orchid potting mix. Not saying you can't use it, just be observant.

[Ray]

An editorial comment, meant to show there are many ways to "skin this cat" rather than start a debate:

Despite what OW, his professional acquaintance, and his research may suggest, I have fed my plants with K-Lite (12-1-1-10Ca-3Mg) for almost 8 years now, and they are doing exceptionally well.

Likewise, there is a west coast botanical garden whose professional horticulturist orchid curator, known for his awarded plants, only uses calcium nitrate!

[estación seca]

And for a little after dinner mint, orchids very happy in your care and growing rapidly will be able to use more fertilizer than those languishing or inactive for the winter.

[Orchid Whisperer]

Originally Posted by Ray

Despite what OW, his professional acquaintance, and his research may suggest, I have fed my plants with K-Lite (12-1-1-10Ca-3Mg) for almost 8 years now, and they are doing exceptionally well

Don't many of your plants also get kelp extract? Significant K in that, so the K is provided, it just comes in through the back gate.

I'm also curious about Maslow's hierarchy (Maslow 1943) with regard to orchids. In orchids, which needs take priority over physiological needs (food, water, etc.), aren't those usually in the foundation of the pyramid? Perhaps safety needs rank higher for an orchid? Maybe belongingness and love come before physiological needs since many orchid growers love their plants? I tend to think esteem needs (sense of accomplishment, etc.) are more of a grower issue; I feel I've accomplished something when I've had a plant bloom, maybe my plants feel they have accomplished something too. I tend to think self-actualization isn't much of an issue with a plant, since they just seem to respond to what I do to them / for them, and don't seem to have creative outlets. As a grower, maybe I should take orchid psychology into account in the future. (Meant in fun; I had to look up Maslow. FWIW you may be interested in "Liebig's law of the minimum").

[Ray]

Originally Posted by Orchid Whisperer

I'm also curious about Maslow's hierarchy (Maslow 1943) with regard to orchids. In orchids, which needs take priority over physiological needs (food, water, etc.), aren't those usually in the foundation of the pyramid? Perhaps safety needs rank higher for an orchid? Maybe belongingness and love come before physiological needs since many orchid growers love their plants? I tend to think esteem needs (sense of accomplishment, etc.) are more of a grower issue; I feel I've accomplished something when I've had a plant bloom, maybe my plants feel they have accomplished something too. I tend to think self-actualization isn't much of an issue with a plant, since they just seem to respond to what I do to them / for them, and don't seem to have creative outlets. As a grower, maybe I should take orchid psychology into account in the future. (Meant in fun; I had to look up Maslow. FWIW you may be interested in "Liebig's law of the minimum").

Music! Don't forget music!

Don't many of your plants also get kelp extract? Significant K in that, so the K is provided, it just comes in through the back gate.

I had considered that, but KelpMax is only 0.7%K, and adding a tablespoon per gallon once a month isn't much.