To Fertilize or Not?
 

[MODERATOR NOTE: Following is a discussion moved from a different thread by me (WaterWitchin) which may be of interest to those beginning their orchid journey]

All mine [Sarcochilus] also outdoors on a NNE facing balcony but with nothing to shade except building structure on the south and east sides. Temps here usually about 10 degrees warmer than SF.

Seen a couple of leaves yellow but seems it’s because there's new growth elsewhere, roots or new fan/leaf, so I think nutrients are just being recycled elsewhere. They definitely grow much slower than Phals.

Plain tap water daily since April. No fertilizer.

What is your reason not to fertilize?

I don’t think they are heavy feeders but I think they certainly will benefit from it. They need their “vitamins” to grow, just like we do.

IMHO, in the end you’ll notice deficiencies.

Nothing other than just being a complete newbie to growing anything other than Phals.

Read many posts that most important is to get cultural conditions right because if they aren't, fertilizing won't help. I agree from personal experience with a couple of my Phals. Since I killed an Oncidium from dehydration, I wasn't even sure I could provide conditions well enough for any of the plants I got last Aug/Sept to survive, let alone flower. Kinda wanted to see how they did for a full year before changing anything up.

A couple have been pooped on by birds. Sometimes gets pretty windy so also had a little leaf litter buildup (read that's where some Sarcs are found in the wild growing on rocks around streams) and some minerals in plain tap water (calcium?) was my rationale that they might still be getting a teeny bit of "natural" fertilizer. But I did buy a general 8-8-8 fertilizer to start trying later this year if any seemed to do well enough.

Orchids are slow growers and it will take a while before deficiencies show up. A year is nothing in an orchids life.

Certainly getting cultural conditions "right" is the most important part. I don't agree with "fertilizer won't help." Yes, as you have discovered, fertilizer won't help if your plant is so dehydrated it can't survive. Neither will it assist with any excess lack of culture with rotting medium, too much light, too little light, temperature that is too cold or too hot for the particular plant, Bird poop and leaf litter buildup aren't particularly important either way unless excessive. Using tap water works for most orchids other than if high TDS you're going to fight mineral buildup.

Fertilizer won't cure cultural conditions that are going to kill the plant in the long run anyway. What fertilizer CAN help with is giving the plant more vigor to survive cultural mistakes while you're tweaking what the plant needs in the way of correct watering, temperature, air, and light.

I use a 12-1-1 10 Cal-3Mag fertilizer with RO water. You don't need to get that carried away, but there's also a reason there's a different NPK for different plants...for example I don't use a fertilizer formulated for tomatoes on my violets or vice-versa.

It can't hurt to use fertilizer, and probably might help. You might want to give them a boost while you're learning the culture. Fertilizer is much cheaper than orchids.

Orchids (and many other plants) in habitat have fungi growing inside through outside their roots. These fungi help the plant absorb nutrients from the surroundings. Orchids grown in labs lack these fungi. Fertilizing is necessary for our orchids.

Many people never fertilize house plants, then they wonder why their plants die. House plant potting mixes contain no nutrients beyond a few the manufacturer may put in the bag. Once these are exhausted the plant has no nutrition. I ask these people whether it would be reasonable to keep a house cat and give it nothing but water and a litter box?

Well, the housecat would show the ill effects much sooner... green plants do take care of the basics - carbs - thorough photosynthesis. Cats need the carbs to live. But eventually, the plants also need to grow new tissue, and that's where the "vitamins" come in . To some extend they can "recycle" tissue from old leaves, spikes, etc. to take even longer to show the effect of not getting the minerals. But eventually it does catch up with them. To thrive (not just survive) they do need a bit of fertilizer. Not much, but they do need some.

Is it possible orchids grown outdoors can pick up mycorrhizal fungi up through airborne spores or decomposing leaf litter? I compost a little on my balcony for my few non-orchid plants.

We don't have the mycorrhizae in our environment that orchid seeds need to germinate... that is why they have to be propagated in flasks with media that provide the necessary nutrients. I would not consider whatever they may pick up from the environment to be a source of nutrition, at least not a reliable one.

I don't know whether just a few fungi coexist with many orchid species, or whether it's a nearly one-to-one species to species cohabitation. Almost all species of orchid need symbiotic fungi in habitat for seeds to survive. The fact that almost no orchid seeds will germinate in cultivation without laboratory intervention tells me the symbiotic fungi do not set up housekeeping with our orchids outside habitat.

The bottom line is a small amount of fertilizer is necessary for orchid growing. Plants we buy come from sellers who probably fertilized heavily to get them to market size as fast as possible. In our care there may be sufficient nutrients stored for some time, perhaps up to a year or more. But once the stored nutrients are gone, the plant will suffer.

Calcium and magnesium may come from most tap water, but other nutrients don't. Nitrogen is always important for plant growth. Plants can't synthesize structural nor enzymatic proteins, chlorophyll, nor nucleic acids for cell division and growth, without an external source of nitrogen.

Edit: At the lecture I heard, Mr. Barrie from Australia said they water their Sarcos at the nursery with fertilizer solution 365 days out of the year.

I don't think I have especially hard water, but because we have similar weather conditions, I'm following the grower's habits the plants came from and between Nov-March, the only watering is what Mother Nature provides. Last Nov had several days in the 70s with only a few days rain so I think I will water more if there are any dry spells like that again, but would you agree the rainwater for these several months should flush out any potential mineral buildup?

I seem to recall San Francisco's water is not high in dissolved minerals. You can find out. Go to your water utility's Web page and look for their annual water quality report.

If you have a winter with a good amount of rain most other orchids will struggle in the cold and wet.

I wouldn't worry about water quality even if you aren't in the city - surrounding areas have a range of levels of solids in the water. But these are not sensitive. Mine get city water and they are fine. When you say "San Francisco Bay area" that covers a huge range of microclimates, so you do need to be a bit more specific with regard to what you experience in terms of temperature ranges.

That was a generic statement. You have to follow what's in your own local environment. No idea whether your rainwater flushes out potential mineral buildup. That depends on too many variables, including medium, the TDS in your own location.

I grow almost everything in semi-hydro. If I used straight tap water from MY tap, I'd have lots of mineral buildup in a short period of time, on LECA, which would have an effect on its porosity. I would have to repot more often, which for some orchids isn't a good idea, or something I desire to do frequently. I grow exclusively inside now. When I grew outside it was a garden hose. We don't get enough rain to depend on for orchids.

So any advice you take, you have to factor in YOUR environment and other cultural differences. It's just generic suggestions to adapt to your specific conditions. I grew in bark for a decade or two, outside half the year, in a basement the other half, only used tap water, and that was a whole different ballgame. The learning curve switching was quite the trip, and I never even left the farm.

The weather only affects water hardness if your supply is surface water. Most is taken from aquifers underground, so the local geology id what affects it most.

OK, so I've had this burning question. Human urine (diluted) is a great source of nitrogen for the veggie garden. So why doesn't anyone use this for orchids? I assume it would need to be diluted even more for orchids since they don't need nearly as much food as plants that grow more quickly. Urine concentration can vary depending on our hydration status. Do all these make using even diluted human urine too unpredictable a concentration (unless you can analyze it in a lab) so it is not practical for orchid use, lest you run the risk of burning them?

I think you explained the reason... it's unpredictable. This is the case with all the rest of the "organic mixtures" that people come up with too. Fertilizers sometimes have their nitrogen as urea, but the amount is known. And orchids need very little. Why would you risk your plants to avoid spending a very few dollars on a bottle of fertilizer that will last for months or more.? Compared to the price of orchids, fertilizer costs nearly nothing.

With a modern diet human urine contains so much salt it is harmful for most plants.

Thanks everyone. I just remembered Roberta recommended the book "A Bay Area Guide to Orchids and Their Culture" and it notes which orchids are very sensitive to TDS. Fortunately Sarcochilus and the others I have are not among these.

One more thing about urine- the nitrogen source is urea, which is not particularly well absorbed by orchids.

There are three types of nitrogen absorbed by plants, nitrate, ammoniacal, and urea. The first two are preferentially absorbed by the roots, but foliar uptake is poor. The opposite is true of urea - it is preferentially absorbed through the leaves, but less so by the roots, unless it has been decomposed to ammonia, a slow process, more so if the medium dries.

The problem is that many orchids, especially as they mature, develop waxy cuticle layers on the leaves that limit foliar uptake, if not prevent it.

Don't we also excrete nitrogen as uric acid? I thought too much uric acid causes it to crystallize in the joints = a gout attack.

Great article Estación Seca. I guess. Didn't finish it. That's a whole lo more about pee than I really need to know. Then again, it does answer questions asked, unasked, and more. :biggrin:

From Should I Fertilize to a study about the effects of using urine. Gonna stick to my K-Lite. Keep going like this, Imma have to move this from Beginner thread to Advanced Discussions. :rofl:

On the subreddit about composting, they are often referring to peeing on the compost pile to get it started. Just thought you could add this to your growing knowledge bank.:rofl:

My dogs already have this one covered. :biggrin:

Well that explains my composting failures :rofl:

You have converted me into a fertilizer-believer :)

Today I noticed one of my phals has a new growth from the stem. Doesn't look like a root to me, so I think it's a spike. Last year's spike didn't die back all the way so I left what was green and a new spike has already started to form off the remnant. This could be the first time I have a Phal with 2 separate spikes coming from the base. It did produce 2 spikes a couple years ago, but it was actually one spike that formed off an old spike that ended up branching.

I think the reason I don't think I really saw any benefit from fertilizing my Phals before was because when I started to fertilize them in the past, by then my cultural conditions weren't so favorable anymore

Way to go!
Show off your Phal once it is flowering <3