Gardening Principles: Light

Gardening Principles: Light

Growing a successful garden takes some careful planning.  You need to consider water, soil fertility, climate, crop rotations, organic matter sources, etc.  But one of the most important things you want to consider from the very beginning islight and how you manage sunlight in your garden.

Light is the source of energy plants use to turn carbon dioxide from the air into carbohydrates that we can eat.  Put simply, plants must have sunlight to make food.  It’s a pretty cool thought to consider that when I bite into a juicy tomato or a crisp apple, I’m eating a bit of sunshine.

In the absence of light, plants loose the energy needed to fuel their food producing systems.  Crops that are grown in the shade will be stressed trying to feed themselves, and if they’re having difficulty feeding themselves, they certainly won’t feed you or me.  In fact, as the sun goes down, plants still need energy to maintain their biological systems, so the production train reverses for that short period, and the plant uses a bit of its stored sugars to feed itself during the night.  When sunlight returns, the plant resumes its carbohydrate producing ability.

Gardening Principles: Light

Gardening Principles: Light

The amount of carbohydrates that the plant uses at night are only a fraction of what it produces during the day to form structural and edible sugars (to learn more about that topic, I think you’ll find this article informative).  But imagine if the plant only got half the amount of light it really needs.  The amount produced, overall, would be hugely reduced, and the ratio between production during the day and energy consumption at night would be much smaller.

The highest levels of food production require the maximum amount of sunlight exposure possible.  Ideally this would amount to 8+ hours of direct sunlight per day, so choose your garden location carefully!  Observe shade patterns throughout the year (particularly from late spring to early fall) and avoid putting your garden in the path of shade on your property.  Where possible, prune back overhanging tree limbs and remove other obstacles that will cast a shadow on your garden.

Also, remember to arrange plants within the garden plot itself so crops don’t shade each other (unless your particular crop requires partial shade).  This means putting taller crops in the back of the garden and shorter crops in the front of the garden.  Not sure which side of your garden is the “front” or “back”? … That’s okay because, in general, it depends on where you live.

Gardening Principles: Light

Gardening Principles: Light

☀ For those in the northern hemisphere, the “back” of the garden is the northern end of the garden and your “front” of the garden is the southern end of the garden.
☀ For those in the southern hemisphere, the opposite is true: the “back” of the garden is the southern end of the garden and the “front” of the garden is the northern end.
☀ First exception: If you live close to the equator, then you’ve got a lot of overhead sun, so there’s not really much of a ‘front’ or a ‘back’.  Even where we are, in the southern United States, the sun seems slightly north of us for 6 to 8 weeks or so.
☀ Second exception: If you live on a hill or mountain slope, it’s going to impact the way sunlight hits your garden, whether you’re in the northern or southern hemispheres.  (Are you on the north, east, south, or west side?)  Besides changing what kind of light and shading you get, the rise of the land will also change the angle that the sunlight is hitting your crops (see image below).

What about growing crops indoors?  Either put crops next to the sunniest window  in the house, or use the brightest artificial light you can find.  If you choose to use artificial light, the closer the light is to your crops (without burning them) the better.  But artificial lights, even the best ones, are significantly inferior to the power of direct sunlight.

Gardening Principles: Light

Gardening Principles: Light

Light color in artificial lighting is of less importance, but for those interested, plants use red and blue light the most.  In order to get a good mix of these two heavily used colors, and the other colors plants use too, white light is the best.  You don’t have to buy any ‘special’ lights for plants; a good white, bright light is best.

As an ending topic and side note, have you ever wondered what it is about plants that actually makes them green?  It turns out that of all the light colors in the rainbow green is the least used by plants.  And because green light is the least used it is mostly reflected by the plant instead of absorbed.  The reflected green light is what we see coming off of the leaves of plants.  So there you have it: plants are green because green happens to be worthless to the plant, but I’m grateful plants don’t use green because I love the color green.

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