I See them on my social media feeds every day – the amazing “home remedy” fertilizers that promise to dramatically boost indoor plant growth. Everything from leftover pasta water to banana peel – even whole eggs – is touted as an all-purpose elixir. But how legitimate are these claims?
Let’s start with pasta water, which contains starch that leaches out during the cooking process. It is claimed that this starch solution, when cooled, is a plant fertilizer, the effects of which work on the miracle.
However, what is often glossed over is that another thing that pasta water can contain quite a bit is salt. Depending on how much you use (Nigella Lawson says pasta water should be “as salty as the Mediterranean Sea”) and how often you eat pasta (one of the UK’s most popular dishes), this could be an enormous amount of salt in your houseplant pots accumulates. Just like in our own body, an excess of salt can dry out plant tissues, hindering their growth and ultimately killing them.
Even if you throw away the salt, starch is made up of carbon, hydrogen, and oxygen, but plants primarily need nitrogen, phosphorus, and potassium for fertilizer, so the nutritional benefits of this liquid to plants seem more than a little shaky.
The same goes for banana peels, which, while often touted as high in nitrogen and potassium, in reality probably contain only a fraction of what peat-standard plant-based foods provide. If people think that the effects of banana peel are really “incredible”, I think we need to invent a new word for how effective the actual fertilizer is in comparison.
Since these are both products that would otherwise be dumped, you could argue that you have nothing to lose, right? Although starch contains few nutrients that plants need, starch is great fuel for bacteria and fungi, including potentially pathogenic types. As such, pouring starch-rich water on your plants is probably not a good idea, especially since mold growth is perfect forage for fungus mosquitoes, little black flies that can soon fill your home.
For banana peels, it’s best to let them rot in the water for weeks before you dose them around your living room plants. Much like the idea of burying a whole, raw egg under the root ball of each potted plant, this is probably just a good idea for those who don’t have many friends or family, or who actually have a good sense of smell.
The final result? Compared to commercially available house plant fertilizers, which are not only specifically tailored to meet the needs of the plants, but are also easier to use and have little to no odor, homemade versions are likely to have more drawbacks than drawbacks. I’m all for horticultural thrift, but fertilizers are one of the cheapest aspects of gardening, especially in the tiny amounts you need for house plants. So save the time and energy to enjoy your plants instead of tinkering with low-value home remedies.
Follow James on Twitter @Botanygeek
