Using Natural and Artificial Light for Indoor Plants

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Grow. Food. Anywhere. (Hardie Grant, 2018) by Mat Pember and Dillon Seitchik-Reardon goes through every fruit and veggie you can think of, giving you the best tips on growing each, as well as the different buggies and diseases that may be coming after your garden. In the following excerpt, they explain the difference between natural and artificial light for your indoor plants.

MacGyver is legendary for his ability to combine a bunch of everyday items to make something useful. Like when he used a sleeping bag, tank of oxygen and vodka to blow himself out of a snow cave. Or when he used a candelabra, microphone cord and a rubber mat to make a defibrillator. Well, when it comes to the use of light, plants make MacGyver look like Huckleberry Finn.

Plants use photosynthesis to convert light energy into chemical energy. A simplified explanation is that when light hits a plant’s leaves, CO2 from the air reacts with water in the plant to create sugars (plant food) and oxygen. Oxygen is the by-product, which is why we talk about places like the Amazon rainforest as the ‘lung’ of the earth. A lot of photosynthesis happening at one time can produce a lot of oxygen. The sugars then spur the growth of the plant.

Just like we need essential vitamin D to be healthy, photosynthesis is essential for the successful growing of edible plants. But there’s a belief among some would-be growers that only direct sunlight can achieve these outcomes. Thinking they don’t possess the environment in which to grow food, they resort to soulless indoor plants, even terrariums, to get their growing fix. It’s a crying shame.

As our cities continue to build up and our living spaces dwindle, direct sunlight is becoming more of a scarce commodity. Thankfully, that doesn’t mean you can’t grow food.

Full Sun Vs. Partial Sun/Shade

Our fruits, veggies and herbs all have their own respective light requirements, but in general, more light is always better. Even if a plant’s tag states its requirements as partial shade, let it be known that full sun is always preferable. Yes, it just may demand some elevated maintenance, more water for example, but more rays almost always translates to better growth.

So, when a plant’s tag indicates it wants partial shade, what it’s really saying is that it may become stressed by hot afternoon sunlight. For these varieties, try to find them a space that collects the gentler morning sun.

Direct Light Vs. Indirect Light

If there isn’t a direct beam hitting a space, it doesn’t mean that it is dim. Different colors and materials will reflect light in varying brightnesses. If your wall is bright white and smooth, it will bounce light much better than one that is dark and irregular. While both may not have direct sunlight, one will be brightly lit and suitable for growing food.

For that reason you shouldn’t become preoccupied with only direct sunlight in the patch. Although much gardening literature will attest to needing 4 to 6 hours of direct sunlight to grow tomatoes, for example, you really don’t need to grab a stopwatch and measure the rays hitting the patch.

Just like MacGyver can find his way out of a snow cave, light has a habit of finding its way to your veggie patch, and reflective light can play a big part in bolstering stocks. So, while we can all make the educated guess that a tomato will not grow in complete darkness, you are never going to know what will grow in your space without trying.

Our advice is to start with plants that are known to be less needy, and then when you succeed, graduate. We’ve seen bananas and avocados grow in the temperate south of Australia, so why can’t a tomato grow between two buildings?

If you happen to be left with a dud of a growing space, with little direct or indirect light, there are still options available. A bright wall will bounce so much more light than a dark one – creating a new spectrum of growing opportunities – and in the event that fails, technology and a host of artificial lights are there to give us a helping hand.

Artificial Light

Our expanding cities mean that natural sunlight, whether direct or indirect, is becoming a scarce commodity. However, artificial lighting is one way to meet the increasing demand for locally and organically grown food without the energy, expense and loss of freshness associated with long-distance transport. Most importantly, it is a way for people to grow food year-round in places where it was previously impossible.

We’ve been generating artificial light for centuries, and flicking a switch to create light is as natural as pulling a carrot from the veggie patch. Well, probably more natural to most. So then, why does the idea of artificial light for growing food seem so unnatural, or at the very least only reserved for those secretly growing plants in their homes?

We tend to be skeptical about new technology, but eventually most people come around. Unlike the clunky, hot and expensive-to-operate technologies of old, LED and fluorescent bulbs have made artificial lighting more accessible than ever before. It doesn’t have to be a complete replacement for old growing techniques, but it is yet another tool. When considering lighting, it is important to think about how natural, visible light affects plants. There are three main attributes:

Intensity – Can be thought of as the power of a light source. Anyone who burns easily has a good understanding of the difference between morning full-sun and midday full-sun. It’s still bright, but there is a difference in intensity. Grow lights also offer a range of intensities.

Duration – Length of time that the sun is out. Plants only photosynthesize in the presence of light, so duration becomes very important. Our summer plants are tuned to long days, while winter crops thrive on short days. Grow lights can customize day length to best suit crops, no matter the season.

Color of Light – As rainbows and prisms often remind us, visible light is actually composed of different colored wavelengths – red, orange, green, blue, indigo, violet. Blue wavelengths are important for vegetative growth, while red wavelengths promote fruit and flower development. Grow lights can enrich specific light colors to maximize productivity.

Fluorescent

By far the most economical to buy, but can be inefficient to run. Generic bulbs provide more of the blue spectrum, but you can get ‘full spectrum’ lights or those that specialize in blue and red. The lights stay cool, allowing you to position them close to the plant where they maximize their growing effect on your plants

LED

More expensive to buy, but more efficient to run. Customized LED lights provide all the wavelengths that plants need and are low heat, meaning you can place them close to your plants. The effectiveness of LED light stays stronger over a greater distance from the plant than their fluorescent counterparts. The most promising technology yet and widely used in commercial operations.

While virtually all edible plants are sun worshippers and will thrive in bright conditions. Some can get by on less direct light than others.

A Dim Corner:

• Mint
• Lemon/lime balm

United Kingdom Light Conditions. What is Sunshine?:

• Potato
• Horseradish
• Ginger
• Jerusalem artichoke
• Turmeric

Bright Space, but Limited Direct Sunlight:

• Leafy vegetables
• Alliums
• Root vegetables
• Cauliflower
• Broccoli
• Cabbage
• Kale
• Brussels sprouts

A Couple of Hours Direct Sunlight Each Day:

• Broad beans
• Beans
• Peas
• Deciduous fruit trees
• Coriander (cilantro)

Lots of Light Makes us Thrive! Often Grown in the Shade of Tall Summer Crops:

• Zucchini (courgette)
• Cucumber
• Squash
• Melon
• Strawberry
• Perennial herbs and vegetables

Lots of Light! Bring on the Sun and Heat! All Sun. All Day. Everyday. We are Tanorexic:

• Chilli
• Capsicum (bell pepper)
• Eggplant (aubergine)
• Citrus
• Tomato
• Basil
• Corn

More from: Grow. Food. Anywhere.:

Easy Home Mason Jar Soil Test
How to Grow Plants from Cuttings
Hand Pollinating your Garden


Excerpted with permission fromGrow. Food. Anywhere.by Mat Pember and Dillon Seitchik Reardon, published by Hardie Grant Books February 2018, RRP $24.99 hardcover.