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Many gardening myths sound logical at first, until they end up harming your plants. One of the most persistent myths is the idea that you can take fresh food waste, blend it into a liquid, and pour it straight onto your garden as an “instant fertiliser.”
A few years ago at the UK’s Gardeners’ World Live show, I saw exactly this being promoted: kitchen food waste, blended into a liquid, then poured directly onto soil as a nutrient source.
It sounds sustainable. It sounds thrifty.
But it’s not good horticulture.
In today’s discussion, we’ll explore why uncomposted organic matter can cause serious nutrient problems, stress your plants, and even attract pests — and what you should be doing instead.
Whether it’s:
…adding fresh, undecomposed organic matter directly to soil can slow plant growth dramatically.
Here’s the science behind it.
When you add fresh material to soil, you’re creating a feast for microbes — bacteria and fungi that break down organic matter.
They have the carbohydrates, but to multiply and do their job, they also need nitrogen.
Because the fresh plant material itself is low in available nitrogen, soil microbes start pulling nitrogen from the soil, taking it away from your plants.
This is called nitrogen immobilisation — and it leads directly to:
This issue shows up everywhere: garden beds, grow media, lawns, farms, and hydroponic systems.
Yes — eventually.
Once microbes finish breaking down the material, they release nitrogen back into the soil.
But the key word is eventually.
If you’re growing:
…that nitrogen may not return in time to support healthy growth.
If you decide to mulch with fresh material, you must compensate by adding additional nitrogen to prevent deficiency.
This applies to:
Failing to add nitrogen almost guarantees yellowing and stunted plants.
Even if nitrogen wasn’t an issue (and it is), adding kitchen food waste comes with another problem:
These pests aren’t just interested in the food — once they arrive, they often start eating your plants too.
This is one of the fastest ways to turn a healthy garden into a wildlife buffet.
The solution is simple:
Composting:
If you prefer fast results, consider high-quality fertilisers, biostimulants, or liquid organic feeds that are formulated to be plant-safe.
Adding uncomposted food waste or fresh plant material directly to soil might sound like a clever shortcut, but it often causes more harm than good:
If you want healthier plants, better yields, and a more stable growing environment, stick to proper composting and balanced nutrition.
Thanks for reading — and until next time, happy growing!
Article by Dr Russell Sharp
If you would like to keep up to date with subjects just like this, you can listen to both our podcasts! Links can be found bellow:
Hydroponics Daily Podcast: https://podcasts.apple.com/us/podcast/hydroponics-daily/id1788172771
Cereal Killers Podcast: https://podcasts.apple.com/us/podcast/cereal-killers/id1695783663