One of the most influential limiting factors for those growing produce all year round in the UK are the low light levels in winter. These low light levels, combined with the relatively short growing season, can make it challenging to grow produce that needs a long time to reach maturity. LED grow lights could be one way to combat these challenges.
What Are LED Grow Lights?
LED stands for Light Emitting Diode. LED grow lights are efficient, durable lights which use far less energy to run than other forms of grow lights and can also take up a lot less space. LED grow lights come in a range of shapes, sizes and specifications, but all could be considered to make it easier to grow a wide range of plants in your polytunnel all year round.
Why Consider Grow Lights?
The main problem faced by UK growers is our short growing season, and the lack of light over the winter months and early in the spring. In order to get worthwhile harvests later in the year, it is often necessary to sow early, when seedlings will often suffer from lack of light. Light starved seedlings can become tall and straggly and will be less resilient to later problems. Often, germination is patchy, and the success rate even lower. Grow lights are a solution to problems with low light levels for indoors seedlings.
Indoors, or in a polytunnel, seedlings can be started throughout the year as long as the requirements for heat and lighting are met. Grow lights are essential for any determined effort to grow for year round eating and mean that you are far more likely to enjoy successful yields from crops such as peppers and tomatoes.
UK polytunnel growers are, for example, often left with a lot of unripe, green tomatoes at the end of the growing season. Starting these early in the year can make it more likely that you can enjoy a worthwhile harvest before the frosts arrive. But tomatoes sown very early in the year can suffer from low light levels. Seedlings can become weak and straggly as they grow tall, desperately seeking sunlight. Grow lights can give tomatoes and other seedlings the light they need early in the year.
Why Grow Lights Are Not What They Used To Be
In the past, the problem has been that grow lights can be cumbersome, awkward and expensive – both to buy and to run. Large fluorescent tubes had previously to be affixed to large grow light structures above your growing areas. This made it difficult for ordinary home growers, who would struggle with the restrictions placed on their efforts by space or by budget.
Nowadays, however, LED grow lights have provided an option that most home growers can use. LED strip glow lights make it easy to turn even a little space on a regular shelving unit or bookcase into a seedling growing area. This means that even those with very limited space in their homes can still manage to grow seedlings over the winter to populate their polytunnels in the spring.
What is more, these lights have now come down in price to the degree that they are now much more affordable to buy and are not out of the reach of most casual home growers. Of course, since they use low power LEDs, grow lights are now also much, much more economical to run. This means that the ongoing costs of food production are significantly reduced.
This winter, do not feel that you need to wait until the spring sunshine arrives to sow any seeds. With LED grow lights, anyone can now get started early with long season crops such as peppers and tomatoes without breaking the bank or turning over a large proportion of your space to seed starting.
Why LED Grow Lights Are Better Than Traditional Grow Lights
There are a number of different grow light options that could be suitable for polytunnel gardeners in the UK. However, there are a number of reasons why LED grow lights could be the best option, including:
- LED lights are eco-friendly and efficient. They use less energy than other grow lights, so can save you money.
- These lights can run for far longer than other lights before dying out.
- LED grow lights run at a low-temperature, which can be beneficial to plants.
- LED options are usually less bulky and take up less space than other grow lights.
- With LED lights, you can customise and alter the spectrum of light and level of light that plants will get. This is not usually possible with other types of grow light.
Tips For Choosing LED Grow Lights
If you have decided that you would like to invest in some LED grow lights for your polytunnel, here are some tips to help you make sure that you get exactly what you need:
Look For Quality. LED grow lights can offer durability and efficiency – but not all LED grow lights are created equal. Make sure you choose quality grow lights from a reputable brand. Read reviews to discover what other gardeners have thought about the options you are considering. Choose an option with a quality semi-conductor chip (which converts electricity to light) that is sufficient for your needs.
Consider Inputs & Outputs. Consider how efficient your LED grow lights will be and how much electricity they will use. Make sure you are aware of how much energy input they will require since they will be running for at least 10-11 hours each day during the winter months. You must also consider the power output of the LED lights you are considering. Will they emit enough light for your purposes?
Consider What You Want to Grow. In addition to thinking about how much light will be emitted by the LED grow lights you are considering, you will also have to consider the wavelengths of the light emitted. Different plants will require different light wavelengths and will need different wavelengths of light during different stages of growth.
Consider How Much Space is to be Lit. In order to work out how many LED lamps you will need, you should consider the size of staging or growing area available. As a general rule, you will need around 32 watts of actual power per square foot for high-light plants like tomatoes, and between 11-18 watts for plants like lettuce.
Consider Ease of Use & Flexibility. Once you have determined whether the LED grow lights you are considering are fit for purpose, suitable for the space you have and the plants you wish to grow, you should also think about how easy they will be for you, the gardener, to actually use.
These are just some of the things to think about when choosing LED grow lights.
LED Grow Lights For Plant Type
When choosing LED grow lights, the most important consideration is what type of plants you wish to grow. Different plants will require different light levels, and different wavelengths of light, for optimal growth.
Green and leafy vegetables, for example, will benefit from a high light spectrum with a balance of red and blue light, while flowering plants will require a low light spectrum so blossoms do not burn. Full spectrum lights are suitable for seeing a plant through its entire growth process, while other specific wavelengths are used to promote healthy blooming or fruit formation.
LED Grow Lights For Your Space
Another important consideration is how much growing space you would like to light. Individual bulbs may be used for potted plants or individual containers, while larger spaces may be lit with strip lights or panels. As a general rule of thumb – when growing tomatoes or other high light level plants you should aim for an actual power output of around 32 Watts per square foot, and 11-18 Watts for lettuce and other plants with a lower light requirement.
There is a lot to learn about growing with LED grow lights, but the above should help you move closer to setting up your new lighting system. As with most things, you can learn and improve as you go along to perfect your set up as you learn what works best in your particular situation and with your specific plants.
Grow Lights Do Work… When Handled Correctly
Advances in modern technology mean that LED grow lights are far more sophisticated than they once were. But like any technology, it really only does what it should effectively when it is used correctly and with an understanding of its strengths and limitations. LED grow lights may not be as good as the sun itself, but they certainly do work in terms of helping polytunnel gardeners to extend the growing season and expand the number of plants it is possible to grow during the dark days of winter.
For more information on polytunnel growing year round, check out our other articles and growing guides. If you have thoughts on LED grow lights to share, feel free to do so in the comments below.
Elizabeth Waddington is a writer and green living consultant living in Scotland. Permaculture and sustainability are at the heart of everything she does, from designing gardens and farms around the world, to inspiring and facilitating positive change for small companies and individuals.
She also works on her own property, where she grows fruit and vegetables, keeps chickens and is working on the eco-renovation of an old stone barn.