How much light do edible plants need (and how to create more if necessary)?

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 Mr Bean.

Plants use photosynthesis to convert light energy into chemical energy. 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 byproduct, 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. Sugars, or plant food, then spur the growth of the plant.

Photosynthesis is essential for the successful growing of edible plants, just like we need essential vitamin D to be healthy. But there’s a preoccupation that only direct sunlight can achieve these outcomes and as we enter winter, and the sun lowers further on the northern horizon, more would be growers are frightened away. 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.

But even as our cities continue to build up and our garden spaces dwindle, and even with the sunlight in shorter supply, it 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 let’s set the record straight - 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 extra maintenance, more water for example, but more rays almost always translates to better growth.

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. In winter time however, just give them as much as you can.

Direct Light vs Indirect Light

Just because there isn’t a direct beam hitting a space, doesn’t mean that it is dim. Different colours and materials will reflect light in varying brightnesses. For that reason you shouldn’t become preoccupied with only direct sunlight in the patch. Although much gardening literature will attest to needing 4-6 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 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?

Creating more light

If you happen to be left with an absolute dud of a growing space, with little direct or indirect light, there are still options available. We’ve now invented the hoverboard and cars that drive themselves, so surely we can find ways of creating a little more light to grow food. Here’s a few options available;

Pruning: if overgrown vegetation is blocking the way, a little bit of pruning may be the solution. It often turns out that the largest vegetative impediments to growing food are deciduous trees, making cool season growing more successful than your spring/summer tilt. We often found this in an old inner city home, where growing throughout winter (when the plane trees were naked) was always more fruitful than the fully shaded summer garden.

Brightening up a wall: just like your outlook on life will change when you paint your moody charcoal living room to a vivid white, your plants will also get the desire to live if you brighter up your exterior walls. If your garden area is made dim through dark walls, consider applying a splash of paint to help reflect more rays. We’ve had great success growing in the narrow passage ways between houses when the walls are bright and reflective.

Wall gardening: if light isn’t present at ground level, we may have no other option that to go up. That’s what we did in our cities to house our swelling population, and while it may be those space efficient buildings that are depriving us of necessary light, don’t curse the solution staring right at you. Wall gardening improves our chances of growing success by chasing the sun skyward. Although most wall gardens prove difficult to maintain - due to the lack of soil depth in the containers - each season sees better and more user friendly systems hit the market.

Artificial lights: 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? We tend to be skeptical and even stigmatise new technology, but eventually most people come around. In this way, artificial light is a bit like online dating. We may still like to do it the old fashioned way, but it is yet another tool in our quest for love and can open up possibilities we never could have explored. At least that’s what my profile says…

Unlike the grow lights of old, which were huge, hot and expensive to operate, developments in fluorescents and, most recently, LEDs mean that artificial lighting is now more affordable, compact, and effective than ever before. Lights can be used to target specific growing needs to both enhance natural light that is already present, or replace natural light as the sole source.

Growing food in our expanding cities means that natural sunlight, whether direct or indirect is becoming a scarcer commodity. However, with more and more people demanding locally and organically grown food, artificial lighting is one way to grow year-round crops without the energy, expense and loss of freshness associated with long-distance transport. Most importantly, it is a way for people to grow food that otherwise may not have any other option. One more tool in our quest for veggie growing domination!