Dangers of underfeeding/under-fertilization?

[BrassavolaStars]

Hello All,

I don’t know if this has been asked before, but I will take a chance that it hasn’t been.

There is a lot of information about the dangers of over fertilizing/overfeeding orchids, but what are the dangers of under-fertilizing?

Is feeding just a question of creating more flowers and more growth than average, or does it actually keep the plants alive?

I am asking this because I fertilize very little and for the past couple of months not at all as I have been in the process of relocating my collection.

Have I been done my plants great harm by neglecting to fertilize for the past couple of months?

[Roberta]

Epiphytic orchids (that's most of what people cultivate) have evolved in a very nutrient-poor environment. They get very small amounts of dissolved nutrients from decaying detritus, maybe occasionally supplemented by a direct hit by a bird or monkey but rarely. They grow slowly. (A tomato plant, which grows a foot a day, is going to need a lot more fertilizer than an orchid that maybe does a new growth or two in a year) So I don't think that your orchids will suffer from a few months of little or no fertilizer. They just may grow a little less than they otherwise might have, and will catch up when you are get back to your normal regimen.

[camille1585]

I agree with Roberta, not feeding for a couple months generally won't have a noticeable effect on orchids, they grow too slowly and need too little food. Maybe they grow a bit slower and make less flowers, but that's about it.

The only exception would be if you have some known heavy feeders. If you happen to have Catasetums in your collection, they are normally their period of very fast active growth, and lack of fertilizer will have a very noticeable effect on bulb size and possibly later flowering.

[Orchid Whisperer]

I have a friend that grows beautiful specimen-size Cattleyas. I once asked him how often he applied fertilizer. He replied "never", then back-pedaled just a bit and said "well, maybe once a year".

The point is, you don't need to give fertilizer very often, orchids don't need much. Skipping a few months should be no problem at all. This is not to say that orchids need zero nutients. They need nitrogen to make proteins that build plant tissue, roughly an equal amount of potassium compared to nitrogen, and significantly less phosphorus compared to the other two macronutrients. Depending on your water quality, you may have enough calcium, magnesium, trace metals and sulfur, or may need to add a little.

[ArronOB]

I used to grow a lot of cattleyas about 15 to 20 years ago. I never fertilised them. Never. I didn’t even know you were meant to. They grew very well and I still have photos of the prolific flowering.

Then interests changed and work closed in and I let the collection go.

I have resumed growing cattleyas as of 3 years ago and now I fertilise them weekly. I can’t honestly say they grow any better then the ones I grew all those years ago.

I guess is should add that the potting mix probably provided a lot of nutrients. It will be different in an inert media.

[Ray]

A horticulture professor once sent me the mass balance calculations based upon carbon fixation in plants, and it struck me as quite remarkable that for any plant to gain one pound of mass, it must absorb and process about 200 pounds of water, but needs only 5 grams of N, P, & K.

[Swimmingorchids]

there you go, ray probably explains it best with the water and nutrient ratio.
The more sun a plant gets the more nutrients it needs but if it gets no sun and goesn't produce any growth adding fertilizer is not beneficial.

The way I look at it is that a plant needs sun, sometimes it is cloudy and the plant doesn't receive as much sun. Does this harm the plant? No, not at all it just grows a bit slower. Does too much sun hurt your plant? Definetely, it will become permanently sunburnt.

It's very similar for nutients. The hard bit is finding the upper and lower limit of fertilizer the plant needs. Always start off weak and experiment by increasing the dosage to see what effect it has, never other way round