Raw fish scraps — including the head, fins, gills, scales and any other fish part that one may not consume — can be a very enriching and boosting fertiliser for soil and plants. Moreover, they are easy to acquire. One can get a handful of complimentary fish scraps with every purchase of fish for meals. Many fishmongers and restaurants happily give away fish scraps for free, as it eases their burden of disposing off the trash to a nearby bin or place of disposal.

The ease of availability and the utilitarian nature of fish scraps make it an instant choice among experienced kitchen gardeners, who have to search for a variety of organic options to improve the soil quality without introducing any chemicals. In this column, we will discuss the benefits, precautions and the process of using fish scraps in gardening.

Mind you, using raw fish scraps in gardening is different from using fish meal fertiliser or fish emulsion, which one can easily prepare at home or purchase from a nearby plant store. The content, preparation process and duration, physical form and other attributes of the end product, the application frequency, process and precautions of fish-based gardening products are somewhat different from each other, but their sole objective is more or less the same, with the plants getting benefits from a highly enriched soil.

There is no absolute, fixed or correct way of using fish scraps in gardening. However, the basic method is to simply bury the raw scraps as deep down in the soil as possible. Many gardeners believe that it takes raw fish scraps roughly one year to fully become part of the soil. I believe that the duration might be dependent upon multiple factors, including the quality and quantity of both the fish scraps and the soil.

Raw fish scraps might repel with their smell, but their high nutrient content makes them a godsend for your garden

Contrary to fish meal fertiliser or fish emulsion, fish scraps are generally applied to a plant once — usually at the beginning of the gardening cycle. The process entails digging a hole in the ground of one foot depth at a place where plants are intended to be transplanted or grown in the future. The fish scraps are then placed within this hole and covered with a layer of soil. Now, as per liking, one can fill it up with more soil and leave it for a few months or instantly transfer a young plant on to it.

The same method can also be adopted with large-sized containers or pots of at least 16x16 inches. In this case, one may need to spread a one-to-two-inch-thick layer of soil at the base of the container. The raw fish scraps are then placed in such a manner that there remains enough space to transfer a plant over them, especially if the shifting of the plant is at the same time.

My favourite practice, involving large clay pots, is to simply put an entire raw fish head over a fine layer of soil. I usually cover the head and scraps with a layer of soil and compost, and then place a seedling or sapling of a tomato plant over it. Then, I add some more soil till I reach the intended upper surface and finally top it off with some powdered egg shells and mulch.

While fish scraps are considered to be extremely beneficial for growing tomatoes, many find them equally useful for other vegetables, especially Armenian cucumbers. Some gardeners use raw fish scraps to grow a variety of flowering plants as well.

Like any other living thing, as the fish head and scraps deteriorate within, they release a number of bacteria and other micro-organisms. This, in turn, attracts earthworms and other bacteria, which increases the overall aeration of the soil and the bacterial activity within.

A systematic soil-enriching cascade ensues as a result of overlapping activities, contributing to the cause. All fish-based gardening products tend to be a good source of a multitude of nutrients, especially nitrogen and phosphorus. As nutrients are released, the boosted soil eventually augments the plant’s growth and development during different stages of the plant life cycle.

We also need to take a few precautions. It is always important to wear gloves or thick plastic bags to cover the hands while holding fish scraps. This is done to avoid exposure to any unwanted infection or injury due to the scales and sharp bones of the fish.

Fish scraps also have a pungent smell, hence storing or freezing them can be a problem. It is better to use them as soon as possible, and to even dig a hole beforehand, to avoid any lag time. While the stench may repel people, it would definitely attract cats, rodents and flies — which can create a nuisance. Cats and rodents may even try to dig out fish scraps and damage other nearby plants as well. It is, therefore, very critical to ensure that raw fish scraps are not only buried deep, but are also covered and packed with soil above.

Please send your queries and emails to doctree101@hotmail.com. The writer is a physician and a host for the YouTube channel ‘DocTree Gardening’ promoting organic kitchen gardening

Published in Dawn, EOS, November 17th, 2024