Category Archives for "Growing with LED Grow Lights"

Even plants are affected by their youth

Anyone debating whether to use fluorescent lighting or LED lighting for indoor gardening, or ​trying to decide on which ratio of red to blue light to use, may well be advised to pay attention to ​this recent South Korean study, especially when it comes to the ​lighting ​requirements of seedlings. In this 2018 study, the researchers briefly grew 2-week old cherry tomato seedlings under different combinations of red and blue light versus a fluorescent light control for 4 weeks before transfer to a regular greenhouse (i.e. natural sunlight) with some striking results.

Seedling light treatment
Abbreviation
0 DAT ^
37 DAT ^
68-75 DAT ^
Fluorescent (+HPS**)
control
less growth
less growth
​smaller harvest
​100% Red LEDs
​0B
​more growth
medium harvest
​87% Red : 13% Blue LEDs
​13B
​more growth
largest harvest
74% Red : 26% Blue LEDs
26B
​65% Red : 35% Blue LEDs
​35B
​53% Red : 47% Blue LEDs
​47B
medium harvest
41% Red : 59% Blue LEDs
59B
less growth
less growth
​smaller harvest
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Best light recipes for growing lettuce indoors

An interesting study ​from NASA published just recently looks at different LED light recipes for growing lettuce indoors. The US researchers grew the Outredgeous variety of lettuce (part of the Romaine family of lettuces but with red leaves) due to its known sensitivity to the light spectrum, where it was grown for 28 days in a special LED grow light chamber, akin to a grow tent with grow lights, called the Advanced Plant Habitat that is used on the International Space Station (ISS). ​The grow lights were on for 18 hours ​per day and a total PAR light output of 180 µmol / m​2 / sec ​was tested using seven different LED light combinations as follows:

Light Treatments
Abbreviation
​Key Lettuce Characteristics Observed
White only
W
​(baseline)
​Red + Blue
​RB
​High ​nutrient ​concentration & small size
White + Blue
WB
​High ​nutrient ​concentration & small size
White ​+ Green
WG
​Fast early stage growth
White ​+ Red
WR
​Fast late stage growth
White ​+Far Red
WFR
​Longer petioles​ & smaller leaves
Red, Green, Blue + Far Red
RGB + FR
​Largest size
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How to grow bigger tomatoes

​For all the tomato growers out there. A study done in 2012 highlights the value of supplemental inter-lighting (lighting that is right in amongst the leaves, providing light to the lower shaded areas of the plants) on tomato production. In this study, the researchers from Japan, grew tomatoes in a greenhouse setting (ie. with natural light) but supplemented with fluorescent inter-lighting. They found that the application of this intra-canopy lighting specifically during the tomato fruit development stage could significantly increase the weight and sugar content of the tomatoes produced.

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The IKEA indoor garden

​​IKEA is one of the latest mainstream retailers to jump onto the indoor gardening bandwagon with their own range of indoor gardening equipment allowing anyone to grow their own herbs at home. The IKEA indoor gardening system is not dissimilar to indoor herb gardens from other indoor gardening specialists, but with IKEA's focus on interior design, the indoor garden ​blends more harmoniously ​into the home. The IKEA indoor garden is simple but stylish in the typical IKEA way. The simplicity of the system makes the setup of ​the indoor garden a painless process that is ideal for the non-green fingered amongst us. Impressively, IKEA even provides ​us with everything ​we need to go from seed to harvestable herbs without the need to look anywhere else.

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Growing Underground

Image of a person tending to a hydroponic farm located in an underground tunnel by the start-up company, Growing Underground

​Once you have got the indoor-growing bug, there is almost no limitation as to where you can actually set up your indoor garden, and if you do it in the right place, the endeavour can even be quite profitable too. Just ask the founders of Growing Underground, who have recently set up an indoor farm over 30m below the streets of London in a disused World War II air-raid shelter of all places.  Crucial to its success is its proximity to lots of food markets and eateries allowing them to carve out a niche in London’s fresh produce market by producing ultra-fresh produce that tastes better and is more nutritious since only having been harvested just a few hours earlier. Growing Underground is the creation of Richard Ballard and Steven Dring, two entrepreneurs that spotted a gap in the London fresh produce market but they also have some pretty impressive directors on their board including Chris Nelson, a consultant well-known in the horticultural arena, and Michel Roux Jr., the chef patron of the Michelin-starred Mayfair restaurant, Le Gavroche. The growing tunnels themselves are located underneath London Underground’s Northern Line where the farm remains isolated from changes in seasonal variations in surface climate allowing produce to be grown year-round. In addition, the underground location is not accessible to typical farming pests and diseases so pesticides are unnecessary making the produce even more desirable. Unsurprisingly, the founders have opted for using hydroponics to make the system as efficient as possible and to dramatically reduce their water requirements, and LED lighting is used to optimise growing conditions while keeping energy costs down. So far, Growing Underground has been successful in marketing Watercress, Thai Basil, Red Vein Sorrel, Pea Shoots, Mustard, Red Amaranth, Garlic Chive, Coriander, Mizuna, Rocket, and Radish, and the company is doing so well that it just recently secured further funding to expand into yet more underground tunnels.

Even the astronauts are doing it!

Image of astronauts aboard the International Space Station (ISS) tasting lettuce grown in microgravity on the ISS

A recent report from NASA has seen the International Space Station (ISS) occupants eating some 'home-grown' red Romaine lettuce which has been cultivated as part of an experiment aboard the space station. Unsurprisingly, they are growing under a mix of red and blue LED grow lamps, but interestingly, they have also included some green LED lights in there too! The green LEDs however are there apparently for aesthetic reasons - to make the 'indoor garden' seem more natural to the astronauts. One has to wonder though, whether the green light might be actually detrimental to the growth as has been documented in some studies, and which might be an important factor when you are trying to optimise limited resources as any indoor gardener knows. Fortunately, this is just the beginning of a whole programme of experiments of in-station growing, which will see NASA engineers working on ways to boost the growth yield, and which might provide valuable information to us back on earth trying to grow indoor gardens. Another interesting feature is their use of a form of hydroponics that includes a synthetic growth media once again demonstrating, what we've known all along, that LED Grow Lights and Hydroponics are the way forward. The primary objective of the ISS experiment is to test systems that could eventually enable astronauts to cultivate vegetable gardens aboard spaceships and other extra-terrestrial structures especially since future space expeditions will be long-term affairs requiring the need for space travellers to grow their own food.  In addition, fresh foods are needed for health and nutrition since many vitamins, minerals and importantly, anti-oxidants start to degrade once fresh produce has been picked limiting the time for which it can be stored.

Farm in a box

​Yet another company to enter the domain of indoor vertical farming but with a twist is the appropriately named Freight Farms. They have opted for a more portable version of the indoor farm by housing it within the common shipping container. The containers use hydroponic technology, and as we know, this can bring about savings in water and plant feed when compared to traditional growing systems. The containers also employ LED lighting for maximum efficiency. The indoor farm environments are all controlled electronically through an app (isn't everything these days !?) maintaining container temperature and air quality at ideal levels for growth. The Freight Farms's containers are divided into two main sections for different phases of plant development, including a seed-starting and early growth section as well as the main growth area for mature plants which are grown in vertical columns to maximise container space. Unfortunately, the container farms are too expensive for the amateur gardener at just over $70,000 a piece but they may be appropriate for someone looking to get into the business of small-scale local farming. More recently, an established traditional Greenhouse supplier, Williamson Greenhouses, has just announced its own version of the shipping container farm, the CropBox. The Cropbox has less capacity than the container farms of Freight Farms but they are more affordable and can even be leased on a monthly basis.

LED light recipes for optimal growth

Image inside one of the indoor grow rooms at the Philips Research Centre in the Netherlands

​Philips, the big electronics manufacturer, has just opened a research centre in the Netherlands that will study the optimal LED lighting requirements for different food crops, in particular, 'leafy vegetables, strawberries and herbs' as well as 'wheat and potatoes'. It is pretty clear that different plant types have different lighting requirements for optimal growth. Even in our own (amateur) grow diaries, we noticed that different plant species grew with differing degrees of vigour (or not) under identical LED lighting conditions and it was clear that there is much more to growing under LED lighting than just simply sticking a plant under an LED light. Interestingly, they say that their lights will contain 'blue, red and far red' which is not unlike many of the more amateur (and cheaper) LED lights available (although the video clearly shows white LEDs as well!?). One can only hope that their 'light recipes' will be freely available as a public resource as more and more of us switch to growing plants under LED lighting.

​For more information, see their press release.