For personal and environmental reasons, more people every day opt to forego eating meat in favour of a plant-based diet. The gardeners among them soon ask if their gardens can run without manure, fish meal and other animal inputs, and the answer is a resounding yes. In addition to using routine organic gardening practices like composting and mulching, which raise the organic matter content of the soil, vegan gardeners should emphasise two other techniques: cover cropping and making homemade plant-based fertilisers.
Solar-Powered Winter Cover Crops
Cover crops (also known as green manures), especially nitrogen-fixing clovers, vetches and peas, use solar energy to manufacture nutrients and organic matter for your soil. The best are winter cover crops that grow when most veggies do not, and explode with new growth when days lengthen in early spring. To explore your options, check out Ben Vanheems’ great video on recharging your soil with winter cover crops.
In my garden, my formula for success with tomatoes and peppers is to plant them in holes dug into the stubble of autumn-sown crimson clover, which is mowed down just as it reaches full bloom in late spring. It is truly miraculous how the plants prosper with no additional fertiliser, have no issues with blossom end rot, and produce generous, tasty crops.
I’ve also started using daikon radishes as a winter cover crop, mostly because the soil likes them so much. The plants grow big in autumn and die in winter, leaving behind deep wedges of rotting organic matter. The dead radish foliage mulches the soil through winter, until I rake it off and compost it in the spring.
Homemade Vegan Fertilisers
Everything costs more these days, and none of us have money to waste, so please think carefully before paying exorbitant prices for vegan fertilisers. Of the few vegan fertilisers available, all are crazy overpriced for what they are, which (in the US) are blends of soybean meal with rock phosphate, dried seaweed, and another seed meal or two. (UK vegan fertilisers often use maize as their base ingredient.) They are good fertilisers and people love them, but at $5 a pound, you could source seed meals and other ingredients at the swankiest health food shop in town and save money.
Better yet, see what you can find at farm supply stores, and get creative. In 2020 I wrote about using organic chicken feed and alfalfa pellets as plant-based fertilisers, but there are many other materials to consider. Don’t get hung up on finding soybean meal, the main ingredient in many American commercial vegan fertilisers. Soybean meal has an impressive NPK of 7-2-1, but when used straight up as a garden fertiliser it is far from perfect. In one experiment, soybean meal reduced germination and early growth of lettuce, turnips and other vegetables, and caused root burn when used around transplanted peppers.
This may not have happened if the soybean meal had been given a week or two to meld with the soil before seeds or crops were planted, which is the best way to work with all plant-based fertilisers. The idea is to feed the soil, allow time for digestion by microbes, and then let the soil feed your plants.
If going to a farm supply store is out of reach, you can still blend your own plant-based fertilisers using plant meals from the store. Soy flour, chickpea flour, and wholemeal bread flour are high in nitrogen, with cornflour not far behind. When mixed into the soil with compost and given a week or two to decompose, any of these flours can do double duty as a garden fertiliser.