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Fertilisation guide for houseplants

While outdoor plants can pull food from the big ground around them, our inside plant buddies only have their little pots to rely on. So, they sometimes need a bit of extra help from us. As we occasionally need a vitamin boost, our leafy friends also benefit from added nutrients. It just keeps them looking lush and beautiful!

Signs your plant needs fertilising

Most houseplants enjoy regular feeding as long as they are growing, often from spring to early autumn. Cacti and succulents thrive in poor soil with less fertilisation, while fast-growing tropical plants like Peace lily, Monstera, and Alocasia require more nutrients. For the best care, always look at your plant's specific care guide and fertilise it as needed during the growing season.

Fertilising your heavy-feeder houseplant regularly will keep it looking healthy and happy. But if you've skipped feeding for some time, your plant might start showing signs that it's hungry for certain nutrients:

  • Yellowing Leaves - While a single yellow leaf might not be a cause for concern, if you notice several older leaves turning yellow, it could be a sign of nitrogen deficiency.
  • Stunted Growth - If your plant isn’t growing as quickly as it used to, or if new leaves are smaller than usual, it might be craving more nutrients.
  • Pale Leaves - A healthy plant should have vibrant, rich-coloured leaves. If the leaves look faded or washed out, it might indicate potassium or magnesium deficiency.
  • Poor Flowering - A lack of blooms or smaller-than-usual flowers can indicate a phosphorus deficiency.
  • Thin, Weak Stems - If stems seem fragile or elongated and are not lighting problems, your plant might need more support in its diet.

Expert tip! Keep in mind these signs are just a guide, and other factors can play a role in the apparition of those signs. Giving your plant too much food can be as bad as giving it too little. Always find out your specific plant needs and change how you care for them based on that.

Care houseplant

When is the best time to fertilise houseplants?

Houseplants generally need fertilisation from spring to early autumn, when they're actively growing due to longer, warmer days. As days shorten and cool in late autumn and winter, some plants slow down and go into a rest phase. This is due to a decrease in natural light and temperature, as well as the inner biological cycles of plants. However not every plant has an inner winter clock, for instance tropical plants don’t know winter as we know it. That, combined with the fact that temperatures don’t decrease that much indoors and that some of us use grow lights, means that your plants might not enter dormancy. The key to fertilising properly is observation: if your plant is still growing, then it still needs food. If it grows slower, it needs food less often. If it does not grow anymore, you can fully stop.

Expert tip! Avoid fertilising during this dormant phase, as plants absorb nutrients more slowly, and excessive fertilisation can lead to potential issues like root burn.

Spring is the period when plants awaken from their winter dormancy, if they had one. And after such a long 'break', they are quite hungry. As they respond to warmer temperatures and increased light, their need for nutrients rises to support this renewed growth. During the growing season, it is important to properly feed your plants.

Did you know? The reason why plants can live so long without fertiliser is not because they don’t need food, it’s because they have a crazy superpower. Unlike humans, plants can reabsorb their own cells, break them down into nutrients and use those nutrients to do something different. It’s as if a starving human could reabsorb his arm to get the nutrients he needs and survive a bit longer. When he would find food, he would regrow his arm. That’s what trees do during autumn: they reabsorb their leaves and break down each cell into nutrients that are stored during winter. Then, they use those nutrients in spring to grow new leaves. A plant that is not being fed will do the same, but the nutrient reserve will slowly disappear and ultimately lead to the plant’s death.

Wondering how often to feed your houseplants? Just check their specific care guide. Each plant has unique needs and will need more or less fertiliser. Some plants will need it more diluted or less often than others. It's always good to try a reduced frequency or a stronger dilution the first time you feed a plant and adjust afterwards if the plant reacts well..

What type of fertiliser is best for houseplants?

You will find on the market several kinds of fertilisers. Some are liquid, some are granular such as Osmocote. Liquid fertilisers provide houseplants with immediate nutrients since they're already dissolved and ready for root absorption, but they need to be diluted with water and given to the plant regularly. Risks of overfertilising are higher with a liquid fertiliser than with a granular fertiliser because all the nutrients are given at once. On the other hand, slow-release fertilisers like Osmocote contain directly absorbable nutrients and, as its name indicates, will slowly and safely release them over a long period of time. That way, the risks of overfertilising are very low, but the risks of underfertilising are higher.

The best fertiliser consists of a special mix of very balanced minerals and nutrients that you add to your water as frequently as your specific plant needs. This will make your plants grow lushier and produce beautiful new (shiny) leaves.

Try PLNTS Nutrition liquid houseplant fertiliser

We love plants and want all our plants to grow strong and beautiful. We like to go the extra mile... Together with plant experts, we have therefore put together a special PLNTS Nutrition liquid fertiliser. One that is full of 'growing power' and is absorbed by the roots of your plant super-quickly so that it can enjoy it as soon as possible. Not only does it help your plants grow healthy and strong, but it even comes in a recyclable bottle. Love your PLNTS, love your planet!

Oh, and before we forget... the PLNTS nutrition is also very suitable for semi-hydro 😉

plants with fertilizer

Here's how this magical mix works…

When we look at our fertiliser's specific composition, it offers a detailed breakdown of both macronutrients and micronutrients:

A. The macronutrients (N-P-K)

  • Total Nitrogen (N): 3.3%
    • From Ammonium (NH₄⁺): 0.7%
    • From Nitrate (NO₃⁻): 2.6%
  • Phosphorus (P₂O₅): 1.4%
  • Potassium (K₂O): 4.9%

So, this formula makes sure plants get the right food to grow. But why do houseplants require these nutrients?

1. Nitrogen (N)

This component is considered to be the most important of the whole nutrient package. This has to do with the fact that this component is essential in the formation of protein, which is what the tissue of the plant is made of for a big part. So, nitrogen actually makes sure your plant stays healthy. Our houseplants can get nitrogen from the soil in two forms: Ammonium (NH₄⁺) and Nitrate (NO₃⁻). Our PLNTS fertilisers already have nitrogen in those forms in our fertiliser, and therefore they are available for plants fast.

2. Phosphorus (P₂O₅)

This component is important for the plant's ability to use and store energy. It’s also vital for photosynthesis, helping plants convert light into energy, and is essential for cell division and growth. It also plays a significant role in flower and fruit production. So, it makes sure your plant is able to grow and develop beautifully!

3. Potassium (K₂O)

This component strengthens the plant, makes the plant more resilient to diseases and strengthens its root system. Additionally, it contributes to the photosynthesis process and is crucial for producing quality flowers and fruits.

The PLNTS nutrient contains a low concentration of N-P-K (3-1-5), which is professionally calibrated and ensures that your plants get what they need without the risk of overfertilising.

B. The micronutrients

The fertiliser is also full of micronutrients that ensure that all processes in your plant work optimally. Think of the formation of flowers and fruits, the absorption of nitrogen and the processing of water and minerals by your plant. They are needed in smaller amounts than the macronutrients but are equally important.

These micronutrients are:

  • Magnesium oxide (MgO): 1,0%
  • Sodium oxide (Na2O): 1%
  • Sulfur (SO3): 0,8%
  • Boron (B): 0,005%
  • Copper (Cu): 0,001%
  • Iron (Fe) DTPA: 0,02%
  • Manganese (Mn): 0,006%
  • Molybdenum (Mo): 0,0004%
  • Zinc (Zn): 0,003%

9 common mistakes to avoid while fertilising your houseplants

  1. Don’t fertilise too frequently. While it can be tempting to fertilise more and more to get more lush and beautiful leaves, using too much fertiliser can lead to a buildup of salts in the soil, which can burn plant roots, leading to brown leaf tips and weakened plants.
  2. Fertilising insufficiently or not at all. While you don't want to overdo it or just think fertilising is not that important, not giving your plants enough nutrients can stunt their growth and make them susceptible to disease.
  3. Not following instructions on the packaging. Every fertiliser is different and comes with recommended dosages and application frequencies. Make sure you read the label!
  4. Fertilising dry soil. Applying fertiliser to dry soil can increase the risks of root burn. It's always best to water your plant first, ensuring the soil is moist, then apply the fertiliser.
  5. If your houseplants are in shock, don't fertilise them. Diseased plants are under significant stress, and their roots already struggle to function normally. They simply can't absorb the fertiliser, the soil might deteriorate, and the already weak roots could suffer further damage.
  6. If your plants are being attacked by pests, don’t skip fertilising. Sap-sucking insects will deprive your plant of nitrogen, so in order to help your plant resist the attack you need to keep feeding it.
  7. Avoid fertilising freshly repotted houseplants. When you repot a plant, you typically use fresh potting mix, which usually already contains nutrients. Also, repotting is really stressful for houseplant roots and extra nutrition can be too much for them to handle.
  8. Don’t ignore the plant’s natural dormant periods. Some houseplants go dormant in the colder months. Fertilising during this period can harm the plant, as it's not actively growing and can't use the extra nutrients.
  9. Avoid using outdated or expired fertilisers. As fertilisers age, the nutrients can break down and become ineffective. Using expired products might not provide the desired benefits and could even harm plants.

Buy plant nutrition at

We hope this has provided you with enough information to feel like a real PLNTS expert! If you would like to get that extra power for your plants to become bigger and healthier, then you can choose between a big bottle of plant nutrition that will last you for ages or the start of small and powerful with our small bottle of PLNTS nutrition - Buy plant nutrition online at

Hi, I'm Emma, your guide!

Hi, I’m Emma, your guide!