Liquid, Slow Release, Organic, NPK, Macro/Micro....Understanding fertiliser might seem a little intimidating when these terms are thrown around. And with so many options on the market now, being discerning is even more of a challenge. But don't let that stop you - Fertilising is an important part of any serious Plant Parent's plant care routine. We created our Indoor Plant Food because we realised so many people had been overlooking the importance of it. A good fertilising regime will keep your plants looking happy and healthy.
As a somewhat confusing side note, fertiliser is not food. Its much easier for us to think of it like food as the term denotes a requirement for life. But plants create their own food through photosynthesis. Fertiliser is more of a supplement, providing plants with the nutrients they would receive themselves in their natural environments by sending out roots and drawing them up from the soil.
Our indoor plants cannot do this. It's up to us to provide those nutrients, in the form of fertilisers. They would still survive if all you gave them was the right amount of light and water, but they would start to struggle - their growth would slow, they may start to lose some of their colour and dull out, or become vulnerable to pests and diseases.
The most important things to look at when choosing a fertiliser are the N:P:K ratios. This stands for Nitrogen(N), Phosphorus(P) and Potassium(K). They are the essential three macro nutrients for plants. The higher those numbers are, the greater percentage of that nutrient is in the fertiliser. Examples might be 10:10:10, or 12:2:12, or 30:0:10. These are all different ratios of N:P:K designed for different purposes and plants.
So what do they do?
Nitrogen - foliage baby! This nutrient is primarily responsible for leaf growth as its a major component of chlorophyll (the compound used by plants to photosynthesize). Plants absorb more nitrogen than any other nutrient.
Phosphorus - root, flowers and fruits! You'll notice fertilisers for flowering and fruiting plants (think citrus feeds) will have a higher number for phosphorus in it.
Potassium - Staying strong and powering on. Potassium helps strengthen the plant's ability to fend off pests and diseases, as well as protecting it against cold or dry weather and build up reserves for dormancy. It keeps the plant's functions performing as they should.
A good fertiliser will also contain micronutrients (sometimes referred to as Trace Elements), making it a complete fertiliser. These micros are the support team to the Big Three mentioned above. They all have a role and will aid plant development.
Slow Release vs Liquid vs Organic
So many options! There are a number of different ways to fertilise your plants, and understanding how they work will help you decide what's best for your situation.
Slow release fertilisers can last up to 6 months, and slowly release nutrients into the soil over a period of time. They are heavily influenced by their environment (temperature and water), and while widely used outdoors they can be harder to manage on potted plants as you risk over-fertilising.
Chemical fertilisers are made from minerals and have precise ratios and quantities of macro and micro nutrients, so you can have more control on exactly what you're feeding your plant and control when they receive it. They're also the fastest acting fertilisers. They are often more concentrated than organic fertilisers and are diluted by adding to water.
Organic fertilisers are the most mild of fertilisers. They will have some decaying organism which can mean a bit of a smell, and will have a lower N:P:K ratio. Because they're organic, you need to make sure they are providing everything your plant needs in terms of macro and micro nutrients, and supplement if its missing anything.
Foliar sprays are a great 'fast fix' for plants especially if they're suffering from a nutrient deficiency as plants take in nutrients quicker through the leaves than the roots. You can get these as ready to go or simply dilute your liquid fertilisers to half or even quarter strength and spray using a mister. They should not be used as an alternative to other fertilisers though as plants would not be able to get enough nitrogen, potassium and phosphorus purely through foliar feeding.
Plant Runner Quick Tips
- Feed (fertilise) in when the plants are actively growing. Generally, this means Spring is the best time but depending on your plant and your home you might find they are growing all year round or stay dormant longer. Plants that are fast growers will need more feed than slow growers like cacti.
- Look for the N:P:K. No N:P:K = steer clear. Understand what it means and what's best for your plants.
- Don't forget the micros! They're still important, your plant just needs less of them.
- Always read the directions to prevent fertiliser burn.