Bloom non-stop w/ no fertilizer, just rainwater?

[karrolhk]

I have seen people growing their Phal in full water culture (water level reaching 1/4th of roots) using JUST rainwater, no fertilizer, nothing! just top up the rainwater when it gets low. and their phal still keeps on blooming and producing new spikes and 3 keikis and all healthy for a whole year!

Where do the nutrients come from? Is just rainwater enough? Is using fertilizer actually redundant?

[estación seca]

The plant might be exhausting nutrients stored in the past. I don't think this would be successful for long.

[Clawhammer]

It's a gimmick

[Cymbaline]

I have seen this too and the claims.

On Facebook there is a Water Culture Orchids & General Care group and one of the admins and a few older members are adamant about how their orchids only need water .

But I do notice that their water culture orchids aren't very old. 1 or 2 years at most. I would like to see how they do long term. Also only certain type do well with this setup like Phals and I think you have to be careful because I notice there are a lot of failures as well as successes .
For me normal medium just seems less risky. The benefits of water is less care is needed but I kind of like caring for my plants. My biggest risk will be when I go on vacation LOL

[SouthPark]

Originally Posted by karrolhk

Where do the nutrients come from?

If the orchid keeps growing well year after year after year, then the nutrients probably come from the grower - as in they add it into the water without telling us.

We know about biological systems - and other processing systems in general. They need certain inputs. And for orchid systems ----- nutrients are necessary inputs. It is like humans ----- no vitamins (eg. vitamin C and other vitamins) ------ and no vital elements ----- then we run into issues with surviving. Same with orchids --- they need their 'vitamins' (aka fertiliser/nutrients/elements).

Some people do grow for example Dracaena fragrans (link) with the base in water. And they could grow for a fairly long time. Some growers might assume that they could keep growing nicely forever without fertiliser etc. But - eventually they will run out of the important elements from within themselves ----- that's if nothing is done to help the plant (eg. by sometimes adding nutrients to the water). This is also under the assumption that the water from the water source doesn't already contain the necessary elements etc in it already.

[Clawhammer]

Its like those people who claim to survive on sun alone. They are lying to you and themselves.

[Roberta]

Because they grow slowly, orchids don't need much fertilizer. So they can run on reserves for a long time. Eventually, they'll suffer and probably succumb. Remember, the day-to-day "food" is from photosynthesis. They need fertilizer to provide the minerals to actually grow - produce new tissue. Think of fertilizer as "vitamins", not "food". So they can run on carbs for a long time. Eventually, it'll catch up with them. A healthy Phalaenopsis can live and thrive for many years... I expect that these "water diet" plants will last a year or two but I'd doubt long-term survival. (Orchid progress is measured in years, not weeks...)

[aliceinwl]

Another thing to consider is temperature. Phalaenopsis do not like cool and wet. If you grow Phalaenopsis at the cooler end of their temperature tolerance, full water culture and semi-hydroponic growing are less likely to be successful without supplemental heating. Roots on most Phalaenopsis will rot pretty quickly if kept wet for prolonged periods at low temperatures (low 70s degrees Fahrenheit and below).

[Cymbaline]

But this water culture isn't the same as growing hydroponically I don't think. Because from what I understand with hydroponics they do add nutrients to the water. I would think for orchids that would be a better option.

[estación seca]

Hydroponics involves pumping a nutrient solution past roots anchored in some inert substance, or spraying the solution on roots dangling in the air - sometimes called aeroponics.

Semi/hydroponics involves a container of inert medium with a reservoir on the bottom, and watering the container with a nutrient solution frequently.

Plants are unable to grow without exogenous nutrients. They may have enough stored to survive for quite some time on pure water without additional nutrients, but they eventually die of malnutrition.

I think this happens frequently with house plants. People don't realize bagged house plant potting mixes lack nutrients, or have only a few that are rapidly exhausted. They water their plants but never fertilize. The plant withers away and people think they can't grow houseplants.

I've tried talking to people about fertilizing house plants. Some people refuse to do it, thinking they just don't need to.