Kids often ask the infamous question, “Why is the sky blue?” and it makes us pause, scratch our heads, and think. I know that mine have asked that question many times. But now that I think about it, I’ve never been asked why the grass is green, even though they spend much more time playing in the grass than flying through the sky.
Which has me thinking, why is grass green? Is it similar to why the sky is blue? Hmmmm…
Time to put my nerd hat on and talk plant science! Don’t worry. There won’t be a quiz after today’s lesson.
The simple answer: Light
The simple answer has to do with light being reflected from grass and how our eyes perceive that light reflection.
Two important things to note:
- Sunlight reaches the earth in wavelengths.
- Every object we look at has a color that falls somewhere along the color spectrum.
Is this triggering something in your brain? Do you remember ROYGBV from grade school: red, orange, yellow, green, blue, and violet? That’s the color spectrum I’m talking about!
We see different colors because of the relation between these two things. Sunlight shines on objects all day long. The object absorbs some wavelengths of visible light. Some bounce back to our eyes. The wavelengths of light that reflect or bounce back determine the color we see.
So, the grass is green because it doesn’t absorb green wavelengths but reflects the green light back at us.
The not-so-simple-answer: Chlorophyll
Now that we’ve discussed the abridged version, let’s dive deeper into the science of grass and how it gets its green color.
Ultimately, grass is green because of tiny molecules called chlorophyll found within chloroplasts, which are found within green plant cells, including the cells of grass blades.
Chlorophyll molecules are made up of a magnesium ion that is bonded to a special kind of organic nitrogen molecule called a porphyrin. These porphyrins are naturally occurring green pigments in plants, algae, and cyanobacteria.
These molecules get their name from the Greek word chloros, which translates to “yellowish-green.” They absorb red light and blue light, the two types plants need for growth.
The span of the electromagnetic spectrum responsible for green wavelengths doesn’t get absorbed by chlorophyll. Instead, green light is reflected off leaves and into our eyes, where the rods and cones detect colors and send signals to the brain, creating your perception of green.
And boom! We see green grass! Not purple, red, or blue.
Does chlorophyll do anything else in plants?
Chlorophyll does much more for your grass than paint your lawn a beautiful verdant shade. It’s also a key component in photosynthesis, the driving force behind plant growth.
When plants photosynthesize, they use light energy to turn water and carbon dioxide into glucose, oxygen, and more water. Glucose, a common sugar or carbohydrate, drives respiration and other metabolic processes and builds starch and cellulose molecules.
The process of photosynthesis occurs inside a plant’s chloroplasts—the same tiny storage organelles inside plant cells where chlorophyll hangs out in the thylakoid membranes. Chlorophyll and some other pigments absorb sunlight and convert the light’s energy into chemical energy in the form of two essential molecules: ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate).
The ATP and NADPH then “fix” CO2 to form 3-carbon byproducts, or sugars, which combine to form glucose. In the end, the initial sunlight energy ends up trapped in the chemical bonds of the glucose molecules.
Clear as mud, right? Just remember that the parts of the grass that help us see it as green also work hard to make the sugar the grass uses to grow.
How to make your grass greener
While we (mostly) aren’t talking lawn care in this article, the whole point of lawn care is to keep your grass green and healthy, right?
So, aside from all the science that goes into your grass’s beautiful color, here are a few essential tips on how you can have the greenest grass on the block and keep it that way:
- Plant the best grass type for your climate and yard. Cool-season grasses are best for northern lawns; warm-season grasses grow well in the South. The exact species depends on if you have sun or shade and how much maintenance you want to do.
- Fertilize your grass regularly using a product with slow-release nitrogen, potassium, and phosphorus. The exact regime depends on the type of grass you’re growing and your soil test results. Check out our articles on what to look for in lawn fertilizer and how to fertilize your lawn to learn more.
- Mow your grass at the recommended height to keep it healthy. Letting it grow slightly longer is always better than cutting it too short. The right height to cut your lawn depends on your grass type.
- Water deeply, yet infrequently. Instead of watering a little bit daily, give your yard a good soaking a couple of times a week. Get more lawn watering tips from our article on when and how to water your lawn.
- Pull weeds and get rid of pests promptly. Lawn weeds, which compete with the grass for water and nutrients, and lawn pests, which eat parts of the grass, can weaken your lawn considerably, turning it brown or yellow instead of the gorgeous deep green you want.
- Aerate every 1 to 3 years to improve soil quality and minimize compaction. Lawn aeration pokes holes in the soil, making room for water and nutrients to reach grass roots. Remember from our science lesson that water is one of the primary components your grass uses to grow!
FAQ About Green Grass
No, you cannot make dead grass turn green again. It cannot be revived by watering or any other cultural practice. You need to reseed your lawn to get new growth. However, if the grass is dormant—which is different than being dead—once temperatures are high enough to break dormancy, you can get it to green up again with regular watering.
If you grow grass without any sunlight or artificial light, it will turn white and die. It needs sunlight to produce the pigment chlorophyll, which reflects green light to our eyes, so it appears green. Grass also needs sunlight for photosynthesis, a metabolic process that uses sun energy, water, and carbon dioxide to produce glucose and oxygen.
While we’re being curious and answering questions about grass, let’s talk about why we call it grass in the first place! According to Online Etymology Dictionary, our modern English word “grass” comes from the Old English word græs, which in turn comes from the even older Proto-Germanic word grasan, which is built on a root meaning “to grow” or “to become green.” A fitting name for a gorgeous green lawn, no?
Does Your Grass Need Some TLC?
Is your grass looking a little pale or lackluster? Does it need a boost to get its green color back to normal? Lawn Love’s lawn care pros understand that sometimes lawn care falls to a low priority on your list, and that’s where they can step in and help.
If you need an extra hand or two to get a green lawn again, reach out online or on the phone, and we’ll put you in touch with a highly-rated local professional who can handle all your lawn care needs!
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