Stinky, sludgey, murky. And delicious for your plants and the soil life! Liquid fertilisers are easy to make, and cost a fortune to buy (sometimes). This week, Edible Oasis has some “recipes” for you to try out.

The best time to apply liquid fertilisers seem to be before and after full moon, when plants swell with water. Koanga Institute recommend two days before and two days after, and that works fine for me – it might be more like the week before and after, but roughly that’s when I do it.

Always dilute your liquid fertiliser, even if you think “it’s not that strong”! More than once, I’ve been foolhardy enough to put it on undiluted and it has burnt the roots, or mined the carbon, Too much nitrogen in one go will use up the carbon in the soil and the structure collapses afterwards. I’ve seen this happen in pots and raised beds especially.

The only infrastructure you need to set up your own liquid fertiliser station is big buckets or troughs, access to rainwater, and a sieve – an old kitchen one can be converted to garden use.

Seaweed fertiliser

First, bring seaweed home from the beach. Some people worry about salt content, but as far as I’ve seen, it isn’t a problem. But if you can, harvest old stuff from high up the beach rather than fresh or growing ones. A day or two after a storm is ideal for doing this!

Second, put to soak in your big bucket/barrel/trough with rainwater. Make sure they’re completely immersed, sometimes a stone on top can help with that. After a few days to a week, it starts to stink and the texture of the seaweed changes. You can now start using it, after filtering and diluting. Then either add more water as you go and let it brew for longer, or use it all up before the smell becomes overwhelming and put the remains into your compost pile.

Best for anything that has trouble with trace minerals (boron, magnesium, manganese…), and works well on any plant that starts to show signs of fungal attacks. It boosts their immune systems. I have managed to stop mildew from spreading on my peas and zucchinis with this.

Comfrey fertiliser

Harvest big nice comfrey leaves, about 1/4 to 1/3 of the plant. Put it in a container with rainwater as above. Leave until it starts to go soggy, smelly and murky (often shorter than seaweed) and then filter, dilute and use!

Really good on heavy feeders, and the nightshade family responds very well (potato, tomato, eggplant, chilli, capsicum…). Great for newly planted seedlings too, they take off well with this treatment.

“Mixed weeds” fertiliser 🙂

Well, the easiest of them all! If you have noxious/invasive weeds in your garden, don’t put them in the compost (where they will become a perennial problem) but in your fertiliser bucket. Cover with water as above, make sure they’re completely immersed, as the tiniest bit can quickly regrow. Soak it for longer, 2-3 weeks may be enough depending on what weeds you have.

Filter this one very carefully, as seeds and bulbs may still be viable. Depending on the stage of decomposition, you may want to bag and bin the residue, or incorporate into your compost pile if it is all just a smelly mess with nothing solid left at all (i.e. definitely no roots, bulbs etc).

Dilute and use as above – this is my “general” solution, and I always have some as there’s always oxalis, tradescantia, convulvulus and other nasties around. A never-ending supply of nutrient rich ingredients, there for the harvest 😉

Adding carbon

To balance the nutrients, you can add molasses to your brew after filtering. If you do this, filter, add a couple of tablespoons per litre, leave open and stir at least twice a day for a couple of days. This adds oxygen, starts some other bacterial growth (aerobic) and should get on top of the smell as well.

Dilution and application

When your brew is ready, dilute 1:10 with rainwater and either use a watering can to add it to the soil, or put it in a spray bottle (I use a pressure sprayer) and apply to the leaves. I usually put it on the soil if I know it is going to rain, thinking the rain would wash it off the leaves anyway, or if I’m short on time. But foliar application (on the leaves) works much much better for fungal infections and is really efficient in summer when it is warm. Apply in the evening if you can, definitely not in the sun, and preferably not just before a big rain.

Good luck!