Chili plants & Light

How much light do my chili pepper plants need?

Our eyes adapt to poor light conditions - that`s why the plant site far away from the window often seems sufficiently bright to us. But plants often no longer gain sufficient light and energy for their metabolism there. For plants to grow and produce flowers, they need light levels of at least 3,000 to 4,000 lux, better more. However, this applies more to plants from our latitudes. Chilli plants that come from the tropics and subtropics need up to 8,000 - 10,000 lux.

For comparison: outside you measure about 20,000 lux on a dull summer day, in sunshine it can be up to 100,000 lux. In winter, about 3,500 lux reach the ground when the sky is overcast. However, the lux level decreases rapidly behind window glass. As a rule of thumb, only 50% of the light intensity reaches the room directly behind the window glass. One metre away from the window, the lux value drops to only 19%. That is only 9,500 lux on an average summer day (approx. 50,000 lux). On an overcast winter day, only 665 lux remain. At two metres, only 10% remains.

When buying plant lamps, it is common to specify the colour temperature of the lamp in Kelvin (K). For chili plants, 5,000 to 6,500 K are considered optimal.

Light Killer

A room can quickly show even less favourable light values. For example, if it faces north or the light is blocked by a house across the street. Also curtains, trees or clouds reduce the amount of light. The available energy from light also reduces as the days get shorter. For this reason, the light problem for houseplants intensifies in winter.

How plant metabolism works

In photosynthesis, a process carried out by plants using light energy, the green parts of the plant convert inorganic substances that have been absorbed into organic substances such as carbohydrates, fats and proteins. If the light level is at the minimum level required, which is around 500 lux, then the build-up of substances only has a slight overweight compared to the breakdown of substances.

Light in winter

From winter to March, when you start growing the heat-loving chilli plants, the brightest window bank is often not enough to provide the seedlings and young plants with enough light. Seedlings develop legginess when there is a light deficiency. This results in long, unstable stems as the seedling tries to grow towards the light. The result can be that the seedlings fall over or become susceptible to diseases and fungi. An artificial light source can help here.

How much light does my chilli need?

Light Duration:

In general, a lighting duration of up to 14 hours daily is optimal for chillies. Less light or a location with shade periods, leads to a delay in flowering. This means: we recommend a lighting duration of 12 hours daily for chilli plants.

Light Intensity:

The minimum for growth in chilli plants is about 3,000 lux. At this light intensity, the plant isn`t very productive and grows only minimally. Leaf formation or flower development is very delayed. They just "exist", so to speak. Optimal is 8,000 to 10,000 lux or even more.

Our recommendation:

Plant lamps are ideal for growing or overwintering chilli pepper plants. In summer, chilli plants are best grown outside, because that is where the light is most intense and strongest. Chilli plants love the sunniest and warmest spot in the garden.
For growing and overwintering, we recommend a plant lamp with LED lights. These are energy-saving and less expensive. Kelvin value should be between 5,000 and 6,500 K. For optimum effect, the plant lamps should be installed close to the plants. With this lamp, the plants should be illuminated for approx. 14 hours.