How to make your own garden fertilisers at home

Using homemade fertilisers ensures that your plants and, in turn, you are getting the right nutrients. Photo / 123rf

With the rising cost of living, we all have to find ways to be more creative with the money we choose to spend and what we invest in. I’m a passionate advocate for growing your own food, which can be a huge cost-saver on your grocery bill - especially if you grow from seed!

However, feeding your plants as they grow can get costly - especially through summer where your plants might need more support to thrive during the hot sun, drought and pest and disease season. Did you know that there are many ways that you can feed your garden from what you grow yourself or collect? You can create some incredibly cost-effective garden fertilisers with plants like comfrey, free resources like kelp and the liquids produced by worm farming or bokashi composting.

Not only are these largely free (or very low cost), they are also super-potent and effective! Remember that if the nutrients aren’t in your soil, they can’t be in your plants - which means they won’t be as nourishing to you either when you come to harvest and cook them! So here are my favourite six homegrown, homemade plant fertilisers you can create and use this summer.

Kelp

If you live near a beach and there is a big easterly blow, head to the seaside and you will find the beach littered with this natural treasure! Kelp can make a valuable liquid fertiliser that is perfect to support your plants during the summer months as it contains all the trace elements, including manganese, potassium and phosphorus and it also helps to condition your soil.

There are many different ways to transform collected kelp into a compost tea for your plants, but the simple way is to put your kelp into a bucket of water and stir once a day for a week. Then, add a cup or two to your watering can and feed it to the base of your plants to encourage a strong resilient plant, more flowers and more produce.

Borage, comfrey and nettles

Borage, comfrey and nettles are all plants you can grow yourself and turn into the ultimate powerhouse combination for feeding your garden. Nettles contain many minerals and nitrogen which is just what your capsicums, eggplants and chillies need. Borage and comfrey provide potassium and phosphorus, which most of your other summer plants thrive on.

Borage is a fantastic plant to grow, as it conditions the soil and burrows deep down which, in turn, aerates the soil. I use both borage and comfrey as a cut-and-drop crop. With comfrey, I harvest the leaves, rip them up and put them under the mulch. With borage, I chop with my spade and place it in the next area I desire to grow.

Borage is a multitasker, conditioning the soil and helping aerate it for healthier plants. Photo / 123rf

Worm farm and Bokashi compost liquids

By far the most easiest and efficient two fertilisers you can create at home for almost nothing are the liquid by-products from worm farming and from bokashi composting. The worm juice is full of fungi and nitrogen-fixing bacteria, and also helps nurse damaged or stressed plants back to life.

Though it is commonly advised that worm juice is so strong it must be diluted before applying or it will burn your plants, I have never found this. Application will depend on how much juice you have available. Usually I mix one litre of worm juice to 10 litres of water in the super-hungry months of my plants’ growth.

Worm farm and bokashi compost liquids are goldmines for garden health, and they're nearly free. Photo / 123rf

Bokashi juice on the other hand MUST be diluted or it could burn or even kill your plants completely. This super-potent power juice should be diluted to the rate of two tablespoons of juice to five litres of water, applied to the soil.

For foliage dilute the juice one teaspoon to five litres of water and spray over the leaves.

Using the juice from the bottom of your Bokashi bin will improve the health of your plants, encourage more flower production and bring a vibrancy to your plants not found in any other fertiliser, in my decades of experience. It can also act as a deterrent and treatment for most pests and diseases. What better way to fertilise your garden with your own fermented food scrap juice? The sheer genius of nature.

My last tip is to remember that, in the summer months, a thick mulch on your garden will keep the moisture and goodness in. The best way to feed your plants is through liquid fertiliser, either applied through a sprayer or in a watering can to the base of your plants, or the cut-and-drop method with borage and comfrey directly under your mulch.

Good luck with your summer garden, and may your crops nourish you just as thoroughly as you nourish them!

For more gardening advice, visit growinspired.co.nz and discover Claire Mummery’s online gardening course at www.growinspiredacademy.com