Feeding chilli plants: when, how & the best chilli fertiliser


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

Chillies are famous for their spiciness. What is less known however, is that the right care and feeding can make your chilli peppers even spicier.

Red and orange chilli peppers growing in a garden bed
The right nutrients can make your chillies even hotter [Photo: kawephoto/ Shutterstock.com]

Chillies belong to the genus Capsicum in the nightshade family (Solanaceae). Basically, chillies are nothing more than hot cultivars of the bell pepper (Capsicum annuum). Chillies are one of the most highly nutritious vegetables. To grow healthy chilli plants with an abundant harvest of fiery red, hot fruits, you need to supply enough warmth, sunlight and water as well as a nutrient-rich soil and good fertilisation. But as always, the right fertilisation depends on a few different factors. Below, we will explain when to fertilise your chilli plants and how to easily spot signs of nutrient deficiency.

When to feed chilli plants

From a little seed to producing fruits, the chilli plant goes through different stages with different nutrient demands. To start off, there is no need for additional nutrients when sowing. A standard growing mediumsuch as our Plantura Organic Herb & Seedling Compost is completely sufficient. This is because, in the first few days of a seedling’s development, it is still making use of the nutrient supply stored in its seed. The high nutrient content of pre-fertilised soils may even negatively impact the seedling’s development.

Fruiting chilli plant in pot
A chilli plant should not be fertilised before it is transplanted for the first time [Photo: Mila Atkovska/ Shutterstock.com]

Only after pricking out and transplanting, should you fertilise your chillies for the first time. Either use pre-fertilised compost for this or work some plant-based granulated fertiliser, such as our Plantura Tomato Food, into the new soil. Sufficient watering will also help distribute this fertiliser into the soil system which allows microorganisms to break down the nutrients and make them available to the plants.

From the end of May onwards, you can transplant the cold-sensitive pepper plants outdoors in a sheltered spot. It is best to improve poor soil with compost or manure beforehand. These natural fertilisers improve the soil structure, activate the soil life and provide the plant with additional nutrients. Potted chilli plants can also be placed outdoors once the threat of frost has passed, but should also be given a larger pot with fresh soil.

When planting out or shortly after, flower buds will begin to form. At this point, potassium and phosphorus became crucial for the plant’s development. It is essential to fertilise in May for the plants to produce lots of flowers and fruits. Specially formulated chilli fertilisers can be hard to find, but many tomato fertilisers contain a similar balance of nutrients and are perfectly well suited for fertilising chillies too. Mineral fertilisers, on the other hand, provide a quick boost of nutrients, but can be harmful if used incorrectly. It is therefore best to use natural slow-release fertilisers, such as our Plantura Tomato Food, which is particularly gentle on your plants, the soil and the creatures in your garden.

How to spot nutrient deficiencies in chilli plants

With too little nutrients, chilli plants cannot grow and will form hardly any fruit. In turn, over-fertilisation is also detrimental to your plants’ health and can lead to a wide range of symptoms. So, keep a close eye on your chilli plant to counteract a deficiency as early as possible. Nutrient deficiencies often manifest in the form of discolouration. Yellowing on older leaves is the first sign of a nitrogen or magnesium deficiency, whereby a magnesium deficiency manifests itself with yellow leaf spots.

However, if young leaves turn yellow, but their leaf veins remain a verdant green colour, an iron deficiency may be the cause. Sulphur deficiency manifests itself in slightly yellow young leaves, as well as stunted growth and a reddish discolouration of leaf stalks and shoots. Reddish or brownish discolouration on the stem and leaves and a steep uprightness of the foliage can indicate a lack of phosphorus. A potassium deficiency, on the other hand, results in deformed or drooping leaves, which later form brown margins and lead to cracks in the fruit skins. Yellow speckled leaves or yellow leaves with green veins indicate a calcium or boron deficiency. However, calcium and boron deficiencies hardly ever occur in ordinary garden soils.

Yellowing chilli plant leaf
Magensium deficiency often results in yellow spots on old foliage [Photo: Alchemist from India/ Shutterstock.com]

It may seem that it is better to fertilise too much than too little. However, an over-supply of nutrients can also adversely affect chilli plants. The trick, then, is to supply the plant with just the right balance of these nutrients. If you notice deficiency symptoms, it is better to act quickly: Choose a fast-acting, liquid fertiliser such as our Plantura Liquid Tomato Food to supply the necessary nutrients quickly.

Liquid Tomato Food, 800ml
Liquid Tomato Food, 800ml
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  • Perfect for tomatoes & other vegetables
  • Liquid fertiliser for healthy plant growth & an abundant harvest
  • Quick & easy application - child & pet friendly

Summary: Fertilising chillies

  • Work compost or manure into the soil
  • When repotting or transplanting, provide the plant with a natural slow-release fertiliser
  • Keep the soil moist so that the fertiliser granules distribute well
  • Watch out for deficiency symptoms and react accordingly

How to feed chilli plants and the right fertilisers

There are many ways to supply your chilli plants with the right balance of nutrients. But this does not have to mean you have to buy the very best all-purpose plant food in the garden centre: Homemade and natural fertilisers can be just as effective! Here is what chilli plants need in a fertiliser.

Feeding chillies naturally: how-to apply

In short, you do not need to use a special chilli fertiliser. Tomato fertiliser with a high potassium content is completely sufficient for pepper plants. A natural, slow-release fertiliser offers many advantages:

  • Microorganisms in the soil break down the granules slowly, providing the chilli plant with nutrients over a longer period of time
  • Promotes an active soil life and a sustainably improved soil structure
  • Good for the environment by avoiding the use of chemicals
Healthy chilli plant with large red chillies and lush green leaves
With the right fertiliser, your chilli plant will thrive [Photo: Ksenia Khmelikova/ Shutterstock.com]

Our Plantura Tomato Food fulfils all these criteria, as it is made up of plant-based ingredients. Granule fertilisers are also easy to measure the right dose and simple to use. To ensure that you supply your chilli plants with the ideal amount of nutrients, we have put together detailed instructions for you below.

Slow release fertiliser: instructions and dosage

  1. Before planting: work 60-110 g/m² (5-9 tablespoons) of our Plantura Tomato Food into the soil
  2. Water well so that the granules break down
  3. After 2 months fertilise again with 50-70 g/m² (4-6 tablespoons)
Tomato Food, 1.5kg
Tomato Food, 1.5kg
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  • Perfect for tomatoes, chillies, courgettes, cucumber & more
  • For healthy plants & an abundant tomato harvest
  • Long-lasting fertiliser that is free from animal products - child & pet friendly

How to feed chili plants with mineral fertilisers

Liquid fertiliser and blue grain plant food are particularly popular for potted chillies. They provide a quick boost of nutrients and ensure a certain basic supply. However, with the wrong dosage, the high salt concentrations in mineral fertilisers can cause slight to severe damage. The spectrum ranges from excessive leaf growth and reduced fruit set to increased susceptibility to fungal diseases and plant death due to the high salt concentration at the root. The leaching of dissolved mineral nitrogen into deeper soil layers can also lead to increased nitrate concentrations in groundwater.

In contrast, natural slow-release fertilisers are much gentler on the environment and there is virtually no risk of over-fertilisation. Soil life is promoted by the introduction of organic material and the soil structure is improved with regular application.

Applying granular fertiliser to chili plants outside
The high salt concentrations in mineral fertilisers can lead to severe even fatal salt damage when not applied properly [Photo: Vitalii Marchenko/ Shutterstock.com]

Feeding chilli plants: coffee grounds and other homemade fertilisers

If you prefer to use natural fertilisers in your garden, you might also use mature compost or well-rotted manure. During flowering and fruiting, it is also good to water your chillies with diluted liquid nettle tea fertiliser (dilute in a ratio of 1:10). This is easy to make yourself and provides the plant with extra nitrogen and potassium. Another sustainable method is fertilising with coffee grounds. You can simply sprinkle the coffee grounds themselves on the soil or add to the irrigation water. Coffee grounds contain essential nutrients such as potassium, nitrogen and phosphorus. It also attracts worms, which help to break down the organic material and loosen the soil at the same time. However, only use coffee grounds as fertiliser in moderation so that your garden soil’s pH does not become acidic.

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