Keeping chilli seedlings under a grow light

We’ve got a light! Just one mind you… but it may multiply. Let’s see if it makes a difference to last year’s au naturel efforts. We have the Phlizon 1200W LED Full Spectrum grow light. Father Christmas did a lot of research and selected this magnificent glowing product. Good work Saint Nick!

Phlizon 1200W is currently strung up with a Heath Robinson style pulley & rope system between bookcase and curtain rail. Dangling 24 inches from the seed leaves of the chilli babies, it gently whirrs in the corner of the room and the seedlings gaze lovingly up at it.

The Dove from Above: Phlizon 1200W,

Why do we need lights?

When us chilli growin’ Brits want to make full use of the heat and light of our limited Summer months, we have to start planting way back in January – especially with those tricky Chinense types. The UK climate certainly presents some challenges when starting this early. Long, dark nights and cold, grey days are certainly not the perfect environment for chillies.

To replicate what a chilli likes, we use a number of techniques that hopefully give our plants a good start in life. One of these techniques is to use a grow light: replacing or supplementing the seemingly absent sun with an artificial source of light. This instantly deals with the lack of daylight hours in a drab Hampshire Winter.

It’s not just replacing like for like either, an artificial sun can be much, much more. You can tailor the wavelength range of lights to suit the particular phase of growing your plants are in. Briefly, green plants (including chillies) need a range of solar radiation (light) of wavelength 450-700nm to grow to their potential. This is known as Photosynthetically Active Radiation (PAR) and happens to correspond to the spectrum the human eye can register.

Photosynthetically Active Radiation (PAR) range that stimulates plant growth corresponds with the spectrum visible to the human eye

For early growth and strong roots the plants need a wavelength range of 450-495nm. This is the blue light range. Imagine a chilli plant in the wild, early in the growing season (Spring and early Summer) sunlight is naturally more in this range.

Later on, during the flowering and fruiting stage at the end of Summer, early Autumn, sunlight has a more red tone, 680-750nm. We can replicate this by switching to the BLOOM light range. Red tones increase flowering and photosynthesis rate.

When producing chilli plants under artificial light we can replicate and enhance what Mother Nature tells us to do.

What types of lights are available?

Fluorescent lighting

This is a good cheap start-up option. Bulbs are readily available in stores and online. The bulbs and units are relatively small and can be fitted well into grow tents. They don’t get super hot and so no need for fans or large distances between light and plants.

High Intensity Discharge lights: Metal Halides (blue spectrum) and High Pressure Sodium (red light)

These are a serious bit of kit. Probably a bit too full on for a home grower like us but something to aspire to if things scale up.

The lights produce a significant amount of heat, which can be a good thing for chillies but will also come with additional tasks and risks. Extra watering, fanning to keep cooler air circulating and greater space to keep the light further away from the young plants are all necessary. The results can be damaging if you get this type of lighting wrong.

So we opted for LEDs…

OK, not cheap to buy a unit but cheap to run. Yes, you have to wade through vast quantities of overseas sellers and their Amazon reviews but once installed they are simple to use, safe for beginners and not too bulky. Better for the environment with low electricity required to run them, long bulb life and minimal heat output.

The Phlizon 1200W is a full spectrum unit which has a VEG switch (to turn on blue and white lights), a BLOOM switch (red and white) and both switches can be used together. Not sure if we will end up using the BLOOM phase light option as the plants will be in the greenhouse by then. Mr Birdhouse is hoping to use the blue phase for his tomatoes, squashes and cucumbers so the chillies may never experience the rosy glow of the red bloom light. Perhaps separate lights for each phase would have been better?

How much light?

We’ve covered why we use additional lighting and what types of lighting are available. Now to think about how much light is required.

Chillies originated in places where there are longer hours of daylight. Perhaps they still remember this and will grow rapidly if this is replicated? 12-16 hours of light seems to be a pretty good amount. Too much of a good thing can be bad for them though so remember to switch the lights off. Keep to your routine and they will reward you with strong growth. A plug timer will help with this (next month’s purchase). A ratio of 16:8 hours on:off seems to be just about right for our growing chillies.