If you grow herbs or salad indoors, one question comes up surprisingly often:
Are grow lights bad for the environment?
It’s a fair concern. Grow lights use electricity, and electricity production has environmental impacts.
But the answer isn’t as simple as yes or no. The environmental impact of grow lights depends on several factors — including electricity use, the crops being grown, and what they replace in the wider food system.
To understand the real picture, you need to look at the entire food system — from farming and transport to packaging and food waste. When you zoom out and look at the bigger picture, small indoor growing setups often sit in a far more reasonable place than people expect.
If you’re new to indoor lighting, our HomeGrower guide to grow lights explains how grow lights work, how much power they use, and how to choose the right setup.
🌍 The Bigger Picture: Where Our Food Comes From
The UK produces only about 60% of the food it consumes domestically, meaning roughly 40% of food eaten in the UK is imported, according to figures from the UK Department for Environment, Food & Rural Affairs.
For fresh fruit and vegetables the dependency is often higher, especially outside the UK growing season.
Many everyday foods travel long distances before reaching supermarket shelves, including:
- fresh herbs
- salad leaves
- tomatoes
- peppers
- chillies
That journey typically involves several stages:
- farming and irrigation
- washing and processing
- plastic packaging
- refrigerated transport
- chilled supermarket storage
- household food waste
Indoor growing removes much of that supply chain — but replaces it with electricity for lighting.
So the real comparison isn’t simply:
Electricity vs farming
It’s closer to:
Electricity vs an entire global supply chain
⚡ How Much Electricity Do Grow Lights Use?
The environmental impact of grow lights depends mainly on how large the setup is.
Small herb lights use very little electricity, while larger grow lights naturally consume more.
| Setup | Typical Daily Electricity Use |
|---|---|
| Small herb light (10W for 16h/day) | ~0.16 kWh |
| Small indoor setup (50W) | ~0.8 kWh |
| Medium grow light (100W) | ~1.6 kWh |
If you want to estimate the running cost of your own setup, try the Grow Light Running Cost Calculator, which calculates daily, monthly and yearly electricity use based on wattage and runtime.
Electricity is the main environmental cost of indoor growing — but numbers only make sense when you compare them with everyday energy use.
🔌 Putting Grow Light Electricity Into Perspective
Looking at grow lights alone can make them seem energy-hungry. In reality, many everyday household activities use similar or larger amounts of electricity.
| Activity | Approx Energy Use | Reality Check |
|---|---|---|
| Boiling a kettle | ~0.1 kWh | One cup of tea if the kettle is overfilled |
| 10W herb grow light (16h) | ~0.16 kWh | Similar to a small desk lamp |
| Laptop used all day | ~0.4–0.6 kWh | A normal work-from-home day |
| Washing machine cycle | ~0.5–1 kWh | One load of laundry |
| 100W grow light (16h) | ~1.6 kWh | Similar to a washing machine cycle |
| Tumble dryer cycle | ~4–5 kWh | Several days of grow light use |
This doesn’t mean grow lights have no environmental impact — they do.
But it helps show the scale. A single tumble dryer cycle can use as much electricity as several days of a typical grow light setup.
🚗 Driving vs Grow Lights: Another Perspective
Transport emissions often surprise people.
A typical petrol car produces roughly 0.16 kg of CO₂ per kilometre, based on UK government emissions data.
A short 10-mile (16 km) round trip therefore produces around 2.5 kg of CO₂.
For comparison:
| Activity | Approx CO₂ |
|---|---|
| Small herb grow light (10W for one day) | ~0.02 kg |
| Grow light (100W for one day) | ~0.2 kg |
| Tumble dryer cycle | ~0.6 kg |
| 10-mile car journey | ~2.5 kg |
That means a short car journey can produce as much carbon as weeks of running a small herb grow light.
📊 Real Example From My Setup
In my own indoor growing setup I measured electricity use using a Tapo P110 smart plug with energy monitoring.
Running a SANSI LED herb bulb, the plug recorded a power draw of about 9 watts.
If run for roughly 16 hours per day, that works out approximately as:
- 0.144 kWh per day
- roughly £1–£2 per month at typical UK electricity prices
Small setups like this are often enough for herbs, seedlings, or small indoor growing areas.
🥬 The Hidden Environmental Factor: Food Waste
One of the biggest environmental costs of food is something many people overlook: waste.
Fresh herbs and bagged salad are among the most commonly wasted foods in UK kitchens, according to research from WRAP.
We’ve all done it: bought a plastic-sleeved bunch of mint for one mojito or a Sunday roast, used three sprigs, and watched the rest turn into a black, slimy mess in the fridge a few days later.
That’s not just £1.50 wasted — it’s the carbon cost of a chilled supply chain ending in the bin.
Home growing changes this dynamic completely.
Instead of harvesting an entire bag of salad at once, you can harvest exactly what you need, dramatically reducing waste.
🌿 Crops That Make the Most Sense Indoors
Indoor growing works best for crops that produce a lot of usable food from a small space.
Good examples include:
- basil
- parsley
- coriander
- lettuce
- rocket
- Asian greens
- chillies
These crops tend to:
- grow compactly
- produce repeated harvests
- spoil quickly when bought fresh
- often be imported outside the UK growing season
A single basil plant grown indoors can produce leaves for months — replacing multiple supermarket purchases.
🥕 Crops That Usually Don’t Make Sense Indoors
Some crops are extremely efficient when grown commercially and require too much space to make sense indoors.
Examples include:
- potatoes
- carrots
- onions
- cabbage
- grains
Large farms produce these staple foods far more efficiently than home setups ever could.
Indoor growing works best when it focuses on high-value crops rather than staple calories.
🍅 A Counterintuitive Example: Tomatoes
Many people assume local food always has the lowest environmental impact.
Tomatoes show why things are more complicated.
Some winter tomatoes grown in the UK come from heated greenhouses, which require significant energy.
Meanwhile, tomatoes grown in southern Spain often grow in unheated greenhouses using natural sunlight, then travel north by truck.
Transport emissions are often smaller than people expect, which means imported produce can sometimes have a lower footprint than heated greenhouse production.
Growing crops like tomatoes indoors is possible, but they require much stronger lighting than herbs or salad greens. If you’re curious what that involves, see our guide to the best LED grow lights for indoor growing.
🇬🇧 Why UK Winter Light Changes the Discussion
Much indoor growing advice online comes from places like California or Australia, where winter sunlight remains relatively strong.
Britain is very different.
In a typical UK January, daylight can be little more than varying shades of grey for seven hours.
Expecting a basil plant to thrive on a north-facing windowsill in Manchester isn’t optimistic — it’s unrealistic.
A small LED grow light isn’t a luxury in these conditions. It’s simply enough light to keep plants growing.
⚡ Running Grow Lights During Off-Peak Electricity
If you’re on a smart tariff such as Octopus Agile or Economy 7, you can often run grow lights during the cheapest hours of the day.
Plants don’t care when their “sunrise” happens — but they still need a dark period each day. If you run lights overnight, make sure the plants sit in darkness during the daytime so their natural light cycle is maintained.
Plants don’t care when their “sunrise” happens.
Running lights overnight can:
- reduce electricity costs
- use surplus wind power on the grid
- make indoor growing more energy efficient
A simple timer or smart plug makes this easy to automate.
🌱 When Indoor Growing Makes Environmental Sense
Indoor growing tends to make the most environmental sense when several factors align:
- the crop is compact and high-value
- the supermarket alternative is imported or heavily packaged
- home growing significantly reduces food waste
- electricity use is modest
Herbs and salad leaves often meet all four conditions.
🌿 HomeGrower Rule of Thumb
If you can eat most or all of the plant — herbs, salad leaves, microgreens — indoor growing usually makes environmental sense.
If you try to grow a large crop like cauliflower or potatoes entirely under lights, you’re essentially fighting physics — and your electricity bill. In bright spaces like conservatories, however, grow lights can still work as a useful supplement when natural light arrives late in the day.
🌿 Indoor Growing Isn’t About Replacing Farming
Indoor growing will never replace commercial agriculture.
Farmers produce staple crops far more efficiently than home setups ever could.
But small-scale growing can still have real value:
- producing fresh herbs and salad locally
- reducing reliance on imports
- reducing food waste
- connecting people with the food they eat
And for many people, it’s also simply an enjoyable hobby.
Like most hobbies, it has an environmental footprint — but when done thoughtfully, that footprint can be surprisingly small.
📎 Related articles
- Grow Lights Explained: A Complete Guide
A broader overview of grow light types, setups, and how indoor lighting works in UK homes. - Grow Light Wattage Explained
A clear explanation of real power draw, wattage myths, and how to compare lights sensibly. - Grow Light Efficiency Explained: Diodes & Drivers
How efficiency affects real-world electricity use, heat, and getting more usable light per watt.