Several studies have focused upon the effects of acids such as oxalic, malic, acetic and citric upon plants. While these acids are detrimental to plants in strong concentrations they are often beneficial in low concentrations.

This pdf paper addresses Cactus and Alkalinity

Some more references for further information:


Foliar Sprays of Citric Acid and Malic Acid Modify Growth, Flowering, and Root to Shoot Ratio of Gazania (Gazania rigens L.): A Comparative Analysis by ANOVA and Structural Equations Modeling
Majid Talebi,1 Ebrahim Hadavi,2 and Nima Jaafari1

Foliar sprays of citric acid and salicylic acid alter the pattern of root acquisition of some minerals in sweet basil (Ocimum basilicum L.)
Noushin Ghazijahani,1, Ebrahim Hadavi,2 and Byoung R. Jeong3

Exogenous Application of Citric Acid Ameliorates the Adverse Effect of Heat Stress in Tall Fescue (Lolium arundinaceum)
Longxing Hu, Zhifei Zhang, Zuoxiang Xiang and Zhijian Yang

Citric acid influence on soil phosphorus availability
Sheila Renata Santos, Enilson de Barros Silva, Luís Reynaldo Ferracciú Alleoni & Paulo Henrique Grazziotti


https://www.researchgate...-as-plant-biostimulators

Citric acid in low dilution appears rather useful and cacti seem to respond well to it.

Cacti are primarily CAM plants
https://en.wikipedia.org...sulacean_acid_metabolism
Both malic and citric acid can be involved with this.

The plants take carbon dioxide at night time and store it as acids that are used to provide the CO2 for use in photosynthesis.

Evidence is growing that indicates that the practice of storing cactus cuttings can cause an increase in alkaloid content over time. The exact mechanisms involved in this do not appear well understood however it can be observed that CAM acids would build up in cacti at least initially when subjected to this treatment.

Citric and malic acids not only appear useful in terms of their growth promoting effects, they may also have an influence upon the alkaloid pathways of these plants, further study is needed.

Very interesting...

Have you tried applying citric or other acids to you cacti or other plants ? If so how did you do it and did you notice any effect(s)?

I only posted about it here because I had excellent results using it with cactus.
I use Ball brand from the grocery store canning section.
I apply at fairly low concentration with a pump sprayer, 1 teaspoon per gallon, at the same time as feeding a low concentration fert like 20:20:20 at 1/2 teaspoon per gallon. I add 10 drops of cinnamon oil if there are fungus gnats.

So your are using this mix as a foliar ,soil drench or both? Is this for the bigger cacti?

I've been meaning to make another order of vitamin c to have on hand for if somehow starts to come down with something; will have to move that up in priority and buy it today.


Do you ever do different npk ratios? As in, using more nitrogen at the beginning of the summer for example? Do you use any micro nutrients or cal or mag sources?

I've been trying to stay away from synthetics as much as possible but I do have a bottle of "dyna gro foliage pro" which is 9-3-6 with 2/3s the N as the nitrate form along with micro nutrients. I also have the cacium nitrate.

I've been thinking of maybe using the synthetics just on seedlings and then switching to organic as they get bigger.

One of most prevalent and destructive problems I've run into starting seeds is mold/fungus/infection... I'm thinking using synths instead of organics might cut down on that..

I might be misinterpreting here, but note that vitamin C is ascorbic acid, not citric acid.

Several acids have similar effects.

I've use to have fertilizer collection, I've worked with plants a long time.
I've been able to experiment with different N:K ratios at different stages of growth.
Larger and more mature plants definitely respond well to increased N.


Since synthetic fertilizer cations are identical chemically to organic fert cations it doesn't matter if you use organic or synthetic sources. Both are best used to create a constant supply of nutrition, both cause issues when used excessively as well.

One of my "secrets" or things people just don't tend to know is that constant nutrition at a low concentration produces spectacular results.