Feeding houseplants: when, how often & the best indoor plant food


I am currently studying agricultural and food economics. As a keen hobby gardener, plants take up most of my free time. A few years ago, I got especially interested in herbs, which is why I completed my studies to become a certified herbalist in 2018.

Favourite fruit: apples, cherries
Favourite vegetables: potatoes, fennel

Not only the plants outside, but also our houseplants need extra nutrients. We show you how to gow about feeding houseplants so they can thrive.

ZZ plant in pot
Houseplants need to be fertilised regularly in order for them to thrive [Photo: KhunYing/ Shutterstock.com]

Every plant, whether garden or houseplant, needs nutrients to survive. If there is an insufficient supply of nutrients, deficiency symptoms can occur and the susceptibility to diseases increases significantly. Therefore, in order for your houseplants to thrive and grow magnificently, you should support them with regular applications of fertiliser. Nitrogen, potassium, and phosphorus are the nutrients that the plant needs most. Of course, we cannot give you a blanket guide for all plants, but we will show you what to consider when fertilising houseplants in general. Below we explain in more detail when and how often you should fertilise your houseplants. We also give you tips on what to look for when choosing fertiliser and the best way to go about feeding houseplants.

When and how often should you fertilise houseplants?

There is no general answer as to when and how often houseplants should be fertilised. Here one would have to differentiate basically more strongly, since the group of the houseplants is very diverse. Basically, however, since the nutrients in the substrate are eventually depleted, they must be replaced from time to time in pot cultivation. Sensitive and slow-growing specimens, such as certain cacti (Cactacea), require only infrequent applications of fertiliser. Most other houseplants, on the other hand, should be fertilised regularly during the growing season.

Various houseplants in pots
Cacti are quite robust, but nevertheless they should also be fertilised from time to time [Photo: Shannon West/ Shutterstock.com]

Should you fertilise houseplants in winter? However, indoor plants should be fertilised only during the growing season because in the cold season the plants need a rest. Only specimens that bloom in winter, such as the christmas star (Euphorbia pulcherrima), should be provided with fertiliser during this time.

Indoor plant food: what is the best fertiliser?

Of course, you should not overdo it with fertilisation, otherwise the plant may even die in the worst case. Less is therefore often more. It is better to fertilise your houseplants more often, but in smaller doses. For the care of your pets are available quite different forms of fertilisers. Therefore, various liquid fertilisers, powders, granules, or even so-called fertiliser sticks are offered in specialised stores. Most often, the composition of fertilisers is suitable not only for one plant, but for several. When feeding houseplants, it is best to follow the application recommendations and instructions on the packaging.

Houseplants along windowsill
Different plants have different fertiliser requirements [Photo: Nukul Chanada/ Shutterstock.com]

Depending on the type of plant, the need for fertiliser is very different. Therefore, if possible, find out in advance exactly what the requirements of each plant. General rule: Houseplants, which are mainly adorned with many large leaves and grow strongly, require more nitrogen than plants that produce many flowers and fruits and need more phosphorus for this purpose. Sufficient potassium is especially important for root formation and the resistance of houseplants.
But not all fertiliser is the same. We explain below what is important when choosing the right fertiliser.

Tip: Proper watering is also essential for healthy houseplants. Therefore, you can find advice on the correct watering of houseplants in our dedicated article.

Feeding houseplants

Because of their sustainability, but also because of their proven positive influence on plant growth and safe application, natural fertilisers are preferable to mineral alternatives. These include, for example, fertilisers such as compost or manure, which are readily used in the garden. However, in the house or apartment, people are more likely to use products from specialised stores.

Liquid fertiliser for houseplants

Liquid fertilisers have the advantage that they can be added quite easily with the watering directly into the substrate. In mineral liquid fertilisers, the nutrients are present as soluble salts that are directly available to plants. However, this carries the risk of over-fertilisation if the correct dosage is not chosen.
On the other hand, due to the high organic content in our liquid fertilisers, not all nutrients are released in one go and the plant is supplied over a longer period of time. One good choice for houseplants is our Plantura Liquid Houseplant Food, which is suitable for many species of indoor plants. The essential nutrients nitrogen and potassium ensure green foliage and strong roots. The basis of our liquid fertiliser is, among other things, leftovers from the food industry, which makes it a particularly sustainable and environmentally friendly fertiliser. It also contains microorganisms that support the growth of the roots.

Person feeding houseplant
Liquid fertiliser is easy to apply – just dilute it into the water you use to water your plants [Photo: fizkes/ Shutterstock.com]

If houseplants convince not only by their foliage decoration, but also form numerous or large flowers, you should resort to a special flowering plant fertiliser. Flowering plant fertilisers have a different nutrient composition than green plant fertilisers and in this way support the flowering of your plants. For flowering houseplants, for example, our Plantura Liquid Flower Food is suitable, which provides the plant with optimal nutrients.

Important: The amount of liquid fertiliser needed depends on the plant. Some species require new nutrients more frequently than others and, accordingly, need to be fertilised more often. The growth rate also provides information about nutrient requirements. Fast-growing plants need more frequent applications of fertiliser than slow-growing plants. Basically, you should rather fertilise regularly and therefore in lower concentrations than rarely in large amounts because too many nutrients can harm the plant. Therefore, before fertilising, be sure to find out the nutrient requirements of your plant and follow the instructions on the liquid fertiliser for dosage.

Slow-release fertiliser for houseplants

In addition to liquid fertilisers, there are also fertilisers in solid form. Fertilisers with a long-term effect provide your plant with nutrients for a much longer period of time than many conventional mineral fertilisers. The nutrients are released by the decomposition via microorganisms and are thus available to the plant in the long term. A sustainable slow-release fertiliser is, for example, our Plantura All Purpose Plant Food. It is largely made of organic ingredients and its composition makes it ideal for those houseplants that prefer nitrogen-rich fertilisation. Our Plantura All Purpose Plant Food in granular form is also easy to dose and simple to use. Plant-based fertilisers also support the build-up of humus in the soil, which has a positive effect on the water balance. Here we have summarised the main advantages of a granular, slow-release fertiliser for you:

  • Particularly gentle for plants, animals, and humans, as no chemicals are used
  • Good for soil life and structure
  • Supports humus build-up and thus improves soil quality in the long term
  • Natural long-term effect
  • No danger of overfertilisation
Three houseplants on windowsill
When feeding houseplants, using the correct amount of fertiliser is crucial [Photo: CLICKMANIS/ Shutterstock.com]

To ensure that you provide your houseplants with the right amount of nutrients, we have prepared detailed fertilisation instructions for you. Of course, depending on the type of houseplant, it may be necessary to adjust the amount of fertiliser to the requirements of the plant. It is best to approach this carefully and gradually increase the amount of fertiliser and the number of fertiliser applications.

Slow-release fertiliser: Instructions and dosage for houseplants

  1. At planting: work about 3 – 5 g/l pot volume (about 1 teaspoon) of our Plantura All Purpose Plant Food into the substrate.
  2. Then water the substrate.
  3. About every three months you can add another 2 – 5 g/l pot volume (about 1 teaspoon) of the fertiliser into the upper substrate layers.
All Purpose Plant Food, 1.5kg
All Purpose Plant Food, 1.5kg
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  • Perfect for a variety of plants in the garden & on the balcony
  • Promotes healthy plant growth & an active soil life
  • Long-lasting fertiliser that is free from animal products - child & pet friendly

Tip: Our fertiliser granules can also be soaked in water for a few hours and then applied with a watering can – thus the nutrients become somewhat more accessible to microorganisms and the effect begins earlier.

Person feeding houseplant while potting it up
Granular fertiliser is worked into the soil when planting [Photo: santypan/ Shutterstock.com]

Feeding houseplants with home remedies

Those who do not want to resort to commercial fertilisers, may even already find in their own household. Indeed, fertilisation with coffee grounds, eggshells and wood ash is also suitable for some houseplants.

Dried coffee grounds can be easily incorporated into the top layers of soil. It contains nitrogen, phosphorus and potassium, and has a weak acidic effect. You can achieve the opposite effect with crushed eggshells. These are rich in lime and other minerals. Thus, they are suitable mainly for fertilising plants that prefer soil with a higher pH. Those who own a stove can also use wood ash as fertiliser. However, this is strongly alkaline and is therefore not suitable for all houseplants. It is very rich in potassium, but at the same time contains lime and trace elements. In addition, ash helps to counteract fungal diseases and rot.

Person feeding houseplants using coffee grounds
You can also use coffee grounds as fertiliser [Photo: Monthira/ Shutterstock.com]

Fertilising indoor plants with minerals

Mineral fertilisers are popular because they usually contain nutrients in high concentrations. However, some plants – such as orchids (Orchidaceae) or succulents – can be quickly overfertilised with it because they have low nutrient requirements. Moreover, mineral fertilisers are anything but environmentally friendly in production. When using natural fertilisers, on the other hand, the risk of over fertilisation is much lower, as they decompose slowly, and the nutrients are only gradually made available to the plant.

In most cases, the care of houseplants includes regular repotting. We have compiled everything you need to know about repotting indoor plants for you.