If you’re relatively new to plant cultivation, it might come as a surprise to find out that your botany routine should involve fertilising plants! If this is the case, don’t worry, most people don’t realise that their plants need fertilising. We have prepared a beginners guide detailing how to fertilise plants - and why they need fertilising in the first place. This should tell you everything you need to know.
Why Do Plants Need Fertilising?
The short answer is that indoor plants will not look as healthy and luscious if they’re not fertilised. It is essential that your indoor plant care regime involves fertilising!
When plants grow in their natural environments, they have access to nourishing minerals, vitamins and soil reserves which restore and replenish their growing cycles. These conditions facilitate peak growing climates. When plants are potted and kept indoors, they will inevitably start to miss their natural environments.
Don’t worry, though - this is where you come in. By giving your plants the proper care and attention, you can fertilise them and restore the mineral and vitamin balance that their soils otherwise come to lack. Knowing how to fertilise indoor plants is a big step on the journey to ensuring your indoor plants are healthy, luscious and thriving.
How Do You Know When Your Plants Need Fertilising?
If we are wondering how to fertilise plants, then the first question we should be asking is: when do they need fertilising? The answer to this is complicated. If your plant is growing well and looking luscious and healthy, then fertilising might be a good method to keep things this way.
If your houseplant is brown, scorched-looking or spindly, then it might be malnourished, in which case fertilising is also a good idea. In short, there is no right answer, but building fertilisation into your houseplant care regime is a good way of ensuring that it is getting the care and nourishment it needs. If you can, fertilise in the Spring and Summer to give your plant the tools it needs to get through the harsher, colder months of the year.
Which Fertiliser Should I Use?
If you want to know how to fertilise indoor plants, then gaining an understanding of the types and benefits of various fertilisers is key. We would strongly suggest doing your research and identifying your plant names and their soil requirements before buying any fertilisers. In the meantime, it is helpful to know that there are a range of fertilisers available, including tablets, sticks, slow-release, granules and liquid.
We recommend granular fertilisers for outdoor plants and liquid and slow-release for indoor houseplants. However, as an alternative to these fertiliser options, you can try using pre-fertilised soil and repotting your plants. This way you can be assured that the right amount of nutrients and minerals are already present in the soil your plant is planted in. This Compact Soil is a great example - consisting mainly of coconut fibres.
If you’d rather use something organic, then try this Organic Plant Food, which comes with an easy-to-administer vial.
Liquid fertilisers are perfect for indoor plants, because they’re extremely easy to administer and provide a steady, diluted source of nourishment to your plants. Simply pour some of the liquid fertiliser into your watering can and water your plants as normal. Consult the specific requirements of your indoor plant to ascertain how often it needs feeding.
Slow-Release fertilisers are another great option for indoor plants. As you would expect by their name, these are not active instantly. Instead they tend to be coated with plastic resin or sulfur-based polymers, which gradually disintegrate and decompose. The protective exterior around slow-release fertilisers breaks down through exposure to water, heat, sunlight or soil, so you don’t have to worry about doing anything to ensure that they will gradually decompose and provide your plants with the nutrients they need.
Granular fertilisers are dry pellets of undiluted fertiliser. This is usually stirred into the compost or soil of outdoor plant pots - either by hand or by using a shovel. It is possible to use granular fertiliser on your indoor plants, though it can be hard to stir and mix the pellets into the soil. Additionally, the nutrients are released as soon as the plant is watered. This means it’s not always possible to create a system of gradual, monitored release.
How Often Should I Be Fertilising Plants?
The answer to this will be dependent on plant-specific requirements. Different plants require different soil-types and thus, different fertiliser regimes. Some plants are more high maintenance and need more fertilising than others. How often you should be fertilising can be ascertained by checking your plant care label or researching each particular plant.
As a rule of thumb, we would recommend trying to fertilise your houseplants somewhere between once every two to 12 weeks, depending on the care instructions particular to the plant you are fertilising. fertiliser should be added to soil during the peak growing cycle of your plants. You can tell when this is as it will be the period in which your plant is growing, producing new stems and leaves, or flowering. This generally occurs in spring.
How To Fertilise Indoor Plants
Check The Soil and pH
Using a soil testing kit, check the pH of your plants’ soil. PH is a scale used to determine the acidity or basicity of your soil. Most houseplants need 6.0-7.0 PH, which is a more or less neutral pH score. Plants such as azalea, pine trees and spruce trees quire an acidic soil of 4.0 PH.
Do some research and find out exactly what soil acidity your plant requires. If your soil testing kit comes up as much more acidic or alkaline than the level you are aiming for, then you can choose a fertiliser that helps you rebalance and thus restore the neutrality of your plants’ soil. Once the soil is at the right pH level, your plant will find it much easier to absorb minerals and nutrients from the soil it’s potted in.
Choose The Correct Fertiliser
We have already given you an idea of the different types of fertilisers available – ranging from liquid to slow-release to granular. Once you know which of these you are using, check the specific labeling on the fertiliser. This will look something like: 5-5-5 or 10-10-10, which reflects that the fertiliser has an equal amount of each key ingredient (nitrogen, phosphate, and potassium). If you have done your research on your plant and checked the soil and pH, you should be able to ascertain which is the right fertiliser for your plant. Alternatively, ask for assistance in a store or garden centre, and an assistant should be able to help you.
Fertilise Your Plant Leaves
Some plants can absorb a great deal of nutrients through their leaves. Do your research, find out if your plant is one that benefits from leaf fertilisation.
Some fertiliser can cause leaf burn or phytotoxicity. If you are going to fertilise your plant leaves then this process is best done by using foliar fertiliser, to avoid damage.
Fertilise Your Plant Roots
One of the main tips we have when it comes to fertilising plants is that you should prioritise root care, and ensure you fertilise your plants’ roots. Add your fertiliser to damp soil when you’re potting or repotting. Alternatively, you can try adding manure, compost or worm casting to the soil as a natural fertiliser.
That’s a Wrap!
We hope this has provided a useful guide on how to fertilise indoor plants. When it comes to fertilising plants it will really depend on the species and condition of the plant you are caring for. There are general rules and guidelines, which we have tried to specify, but generally - the more research you do and better understanding you have of each particular plant, the more successful your indoor plant care will be!