Lazy person’s adventures in fertiliser-making

Gardener:Southern Gardener

Date:13 Oct 2020

Blog Type:Vegetables

Thought I would write about my cheap & lazy person’s adventures in fertiliser-making. I do love how easy and reliable commercial fertilisers are (thank you Yates and Sarah for my Vegie Fertiliser and other goodies!). But I also find DIY fertilisers are fascinating: the chemistry, the ‘natural’ reassuring smell and the way the look of them freaks out our little niece and nephew when they visit!

One of the most fascinating sources I’ve found was this NPK table of things organic:

NPK value of everything organic!

But I’ve found no sources with NPK ratio suggestions for the decomposed organics. Let me know if any of you have seen anything! Meanwhile, these are the liquid feeds I’ve been trialling, in all cases all I've done was fill the vessels with the organic material, topped with water and waited 1-2 months, stirring occcasionally:

Seaweed tea

Suspected NPK ratio: 1.9-0.25-3.68 but would surely depend on the type of seaweed?

Stench rating: 5/10

I’ve really optimised my seaweed tea ritual: when pushed down, the rock that holds seaweed down actually mixes the liquid and aerates it (lazy, I know). And my partner drilled the holes of my watering can slightly larger so that no seaweed bits ever get stuck.

The salt doesn't seem to be a problem, I did not wash my seaweed as I read a tiny bit of salt can be good to fight the vegie nasties. Sand is definitely not a problem as it improves soil drainage.

No fertiliser burn and no unhappy plants from this one, the only downside is that seaweed takes aaaaages to break down. The seaweed in my bucket was put there in July… it’s probably time to move it to the compost bin and start anew.


Comfrey tea

Suspected NPK ratio: 1.8-0.5-5.3

Stench rating: 10/10, lingers for a few hours

The upside - comfrey is very fast to break down and also a very fast, easy to grow plant which is easily propagated from the tiniest piece of a tuber. However, it is annoying to strain out for watering can use, as it breaks down into small slimy bits. Next time I will put the leaves in an old onion bag to make a comfrey 'tea bag' so I don’t have to strain the liquid out. Let me know if anyone knows any other solutions to this one!

The smell of comfrey tea deserves a separate mention. They tell you to make your liquid fertilisers in lidded buckets, and, when it comes to comfrey, they are right. I’ve made comfrey and banana peel teas in two old watering cans (with view of watering straight out while the liquids are young and require no dilution, genius, I thought). Will have to find some sort of cover for them now. Also, first time I used comfrey tea was to water citruses by my partner’s home office window – that’s how we know the smell lingers for a few hours!


Banana peel tea

Suspected NPK ratio: not sure, but high in potassium

Stench rating: 6/10

This has been my rose liquid fertiliser. It’s easy to use, doesn’t seem to block up the watering can, breaks down easily and doesn’t smell as bad as comfrey.


Do you have any trusted DIY fertiliser recipes? I’ve noticed some bloggers mentioning fish… I assume we are not talking about using supermarket salmon here, which is priced the same as gold lately haha

Happy gardening :)

Lazy person’s adventures in fertiliser-making