Perhaps the easiest way to describe veganic gardening is that it is like organic gardening but without using any animal or fish products such as bone meal. You may think that this sounds unduly restrictive, but for people who follow a vegan diet these things matter. And when it comes to it there are many other forms of natural fertilizer like compost that are allowed. To learn more read this article which I found on the Gentle World website.
Vegan-organic gardening avoids not only the use of toxic sprays and chemicals, but also manures and animal remains. Just as vegans avoid animal products in the rest of our lives, we also avoid using animal products in the garden, as fertilizers such as blood and bone meal, slaughterhouse sludge, fish emulsion, and manures are sourced from industries that exploit and enslave sentient beings. As these products may carry dangerous diseases that breed in intensive animal production operations, vegan-organic gardening is also a safer, healthier way to grow our food.
In veganic growing situations, soil fertility is maintained using vegetable compost, green manures, crop rotation, mulching, and other sustainable, ecological methods. Occasional use of lime, gypsum, rock phosphorus, dolomite, rock dusts and rock potash can be helpful, but we try not to depend on these fertilizers as they are non-renewable resources.
Soil conditioners and fertilizers that are vegan-organic and ecologically sustainable include hay mulch, wood ash, composted organic matter (fruit/vegetable peels, leaves and grass clippings), green manures/nitrogen-fixing cover crops (fava beans/clover/alfalfa/lupines), liquid feeds (such as comfrey or nettles), and seaweed (fresh, liquid or meal) for trace elements.
A border of marigolds helps to deter certain insects, and they also have a root system that improves the soil.
See more at Gentle World