Social Media is convinced that gelatin powder is a great fertilizer for plants. It is easy to use, organic and has a high level of nitrogen. Seems perfect for houseplants and the garden.
Is this just another myth or is there something to this advice?
Gelatin Powder Fertilizer
What are the claims for gelatin powder?
“a houseplants best friend …. add vigor and new luster to your Boston ferns, African violets, colorful caladiums, or any other of your household favorites”
“gelatin has been found to be an excellent time-release fertilizer; a natural, nonpolluting, non-burning source of nitrogen.”
“Pure unflavored gelatin can be used as a homemade organic fertilizer” “Just dissolve the unflavored gelatin in hot water, let it cook and dilute it with plenty of water and you have a nearly all nitrogen liquid fertilizer”
“While unflavored gelatin provides lots of nitrogen, most plants need phosphorus and potassium too. Add phosphorus and potassium to your plants by chopping up all of your banana peels and putting them in a jar of water. “
“You simply pour it into the potting soil once a month without risk of overfeeding or fertilizer burn”
Lets have a closer look at these statements.
No risk of burning or overfeeding and yet it is “nearly all nitrogen”? How can it be both? Oh I see, you add it to water and “dilute it with plenty of water” and then claim it is still “all nitrogen”. What about the water part which is the majority of it?
Gelatin powder will add vigor and luster to plants, but such claims never define what this means. How much more does it grow? And what is a “non-burning source of nitrogen”, and why is that important for a garden?
It provides nitrogen, but if you want some P and K you need to add it – so clearly gelatin powder is NOT a fertilizer.
These are social media claims, but what are the facts?
What is Gelatin?
Gelatin powder is a derived from collagen taken from animal body parts. It is a mixture of peptides and proteins that contain carbon, hydrogen, oxygen and nitrogen. Zero phosphorus or potassium.
It is used as a thickening agent in such products as cosmetics, face creams, shampoos, marshmallows, ice cream and photographic film.
Nitrogen in Gelatin
How much nitrogen is in Gelatin? Based on the molecular formula for gelatin, C102H151N31O39 , it contains 18% Nitrogen and this is confirmed by Encyclopedia of Food Science and Technology.
Preparation of Gelatin Fertilizer
A common recommendation for mixing the fertilizer is one packet per quart of water, but I have also seen suggestions that adding one packet to a rain barrel works.
One packet of Knox gelatin contains 7 g, which is 1.26 g nitrogen. A quart of water is 950 ml, or 950 g. That is a 0.13% solution, or an NPK of 0.13-0-0. A very weak source of nitrogen.
Does Gelatin Powder Work?
It is certainly not a fertilizer since it contains no P and K. But does it make plants grow better?
Adding gelatin capsules next to seeds does increase shoot growth: “treatment with two gelatin capsules placed adjacent to each seed increased shoot dry weight of cucumber, pepper, broccoli, tomato, arugula, and field corn, by 138, 244, 50, 45, 41, and 18 percent, respectively “, and “there was a positive linear relationship between the number of gelatin capsules from 0 to 3 capsules on plant growth and plant nitrogen content.”
Since gelatin is a protein, we can expect bacteria to decompose it and turn it into ammonium or nitrate ions, which plants can use. It really is no different than any other type of organic matter. This makes gelatin a slow release nitrogen source, but probably not as slow as other hard to digest sources like fall leaves.
The amount of nitrogen in the above mentioned mixture is very low. No doubt it helps plants but you can expect the effect to be small. It could be used for a couple of houseplants, but seems very impracticable for the garden. There are many cheaper sources for nitrogen.