To fertilize or not to fertilize orchids ?

[Cymbaline]

There was a recent discussion in another Orchid group on Facebook about fertilizers and many members making claims about how they never fertilize and have X amount of spikes. One member mentioned that at an Orchid society meeting she was told that many of the members didn't fertilize.

I came here to ask about this because I follow the 3 week fertilize and 1 week don't rule that I came across with MSU's fertilizer by repotme.

I also saw a recent post by Ray made about a Fertilizer Dispenser but I didn't' want to hijack that conversation with my own question.

I'm just wondering what people here think regarding fertilizing ? Is it beneficial or not? Do you fertilize? I always thought it was but maybe I'm wrong here.


Thank You!



Just my experience when I inherited my aunt's orchids in 2017 , I didn't really do much with them until 2019 . In 2019 these guys got a new grow light plus weekly fertilizer soaks.

Hard to tell which ( if either ) was the benefit or more of a benefit to them because for the first time in years they were developing new growth .

[Clawhammer]

Plants need nutrients to grow. If they are not planted in a media that provides that then fertilizing seems like a requirement. Orchids are (mostly) slow growing and do not grow in rich organic media in nature. As a result orchids mostly have lower nutrient requirements than terrestrial fast growing plants but they definitely still need a nutrition source. There is an optimal amount of nutrition supplementation for each orchid in each environment and finding that optimal amount is important to getting the best growth.

[Ray]

Of course they need nutrition - what doesn't? They don't need much, though.

Orchids are about 99% carbon, oxygen, hydrogen and nitrogen, and about 1% everything else. Of the 99%, everything comes from air and water except the nitrogen, which has to be acquired from somewhere else.

As a general rule of thumb, in order to put on a pound of vegetative mass, all plants need to absorb and process about 25 gallons of water (~200 lbs or 95 kg), but only 5 grams of N-P-K fertilizer.

A corn (maize) plant may add a pound a month, a cattleya might do so in a year, a phal over 2-3 years, and a tiny pleurothallid might not ever add that much.

The plants belonging to folks who "never feed" are getting it from somewhere, and when that residual supply is exhausted, their blooming and growth will diminish.

[mook1178]

Is it possible that some community water sources have enough nitrates that they don't need to fertilize? Also those that use rain water definitely have enough nitrates for orchids that fertilization is not necessary.

[DirtyCoconuts]

Originally Posted by mook1178

Is it possible that some community water sources have enough nitrates that they don't need to fertilize? Also those that use rain water definitely have enough nitrates for orchids that fertilization is not necessary.

why do you feel that rainwater will satisfy the needs of the plants? isn't rain water completely clean of any elements?

[Ray]

Nitrates in drinking water is possible, but generally is considered a no-no, especially over 10 ppm for babies.

I don't agree with the rainwater "definitely" being a sufficient source of nitrogen, but there's a lot more than just H2O in it:

https://pubs.usgs.gov/wsp/1535p/report.pdf

[mook1178]

Ray

I agree definitely sufficient was probably over stated. I think it may depend on location, collection and storage, and location. If the rain water is collected in a large barrel and stored long enough with decomposing matter,I personally would not use fertilizer.

[SouthPark]

Originally Posted by Cymbaline

There was a recent discussion in another Orchid group on Facebook about fertilizers and many members making claims about how they never fertilize and have X amount of spikes.

Definitely - claims of never fertilising is one thing. But adequate details (from them) would be required. This includes growing media, growing conditions (where the plant is placed or mounted or potted), and what sort of water they use, and water-analysis results (details). Also - details about what they find or see inside the pots (after a long time of growing).

For growers that sometimes re-pot orchids (upgrading to larger pot etc), some may find cases of insects/organisms living in the pot, or some sorts of harmless fungi growth etc. Some factors may allow the orchids to acquire the 'nutrients' that they need without 'manual fertilisation'.

[Ray]

Yeah, I've heard the "my grandmother never feeds her plants.." line many times.

Once or twice it was followed up with "Manure tea isn't food, is it?"

[Orchid Whisperer]

Rain water definitely picks up nitrogen from the air, which is mostly nitrogen. It isn't a lot, but some environmental calculations that have to do with plant nutrient budgeting require atmospheric nitrogen to be factored in (I think 5 pounds N per acre is correct, but this is probably quite variable, and I suspect rainfall-related).

Even in the most pristine of environments, rain will pick up dissolved gases, dust, organic matter, etc., so it is definitely not free of all elements.