Botany of Hibiscus: Chlorophyll

Chlorophyll in plants is that amazing green substance that turns water, air, and sunlight into food. Most of us (at least most mothers!) at some time or another, while cooking yet another dinner for our human offspring, find ourselves wishing that we humans could just produce chlorophyll in our bodies to make our own food so we wouldn’t have to spend so many hours of every day in the tedious process of providing food for our families. But strangely enough, we do have a substance very similar to chlorophyll in our human bodies – hemoglobin! Yes, the stuff in our blood that makes it red, the important part of our blood that picks up oxygen and carries it to every cell in our body, is very similar to chlorophyll. The molecules are the same special type of chemical ring, only chlorophyll has green magnesium in the center and hemoglobin has red iron in the center. Unfortunately for us though, our red molecules don’t turn air, water, and sunlight into food!


Chlorophyll Molecule
Magnesium in the Center

Still, it does help to realize that chlorophyll is as important for plant life as red blood cells are to animal life. A chlorotic plant that has too little magnesium to produce chlorophyll feels about as sick as an anemic animal that has too little iron to make red blood cells. Anemia and chlorosis have much in common. In both states, the plant or animal can keep dragging along, and a mild case at least won’t kill them. But an anemic animal and a chlorotic plant won’t thrive either! So if you keep your hibiscus plant blooming and blooming, but don’t stop to notice sickly yellow leaves, you could be working your plant into a state of very poor health.


Hemoglobin Molecule
Iron in the Center

Chlorosis, like anemia, is easily remedied with good nutrition. Part of good nutrition for plants is the sun since they use sunlight to produce their own food. So during the winter months when your hibiscus may be getting a lot less sunlight, it’s important to make sure you keep the levels of nutrition up – particularly the nutrients involved in producing chlorophyll: magnesium, iron, and nitrogen. Instead of stopping all fertilizing in the winter, just cut down your fertilizing a little bit, but make sure you don’t starve your hibiscus by giving them no fertilizer at all. We would never consider stopping all nutrition for our children or our animals in the winter, or stopping their vitamins, or allowing them to eat only junk food. Plants are not as different from animals as we might think.

How does Chlorophyll Work?


Chlorophyll from a
hibiscus leaf starts
off bright green

In its most simplified explanation, when sunlight hits a chlorophyll molecule, electrons on the molecule get excited and start to move. Those jumping electrons cause electrons on the next chlorophyll molecule to move, and the movement, or energy, is passed from one molecule to another until it is used to build glucose, the primary food of both plants and animals. This process, photosynthesis, goes on continually with all chlorophyll molecules in contact with sunlight all through the daylight hours. Then, just as animals move glucose through blood to all cells in the body, plants move glucose through their sap to all cells within the plant.


Under a bright light
chlorophyll glows red
as the electrons get
excited & move

So how do we help our plants continue to make glucose in the low-light conditions of winter? There are two ways to produce more glucose in plants – one is to provide more light, and the other is to provide more chlorophyll. An increase in either light or chlorophyll will increase glucose production. So in the dark days of winter, providing more of the building blocks of glucose – lots of magnesium, iron, plant hormones, and nitrogen – will help the plant make more chlorophyll and maximize use of the small amounts of light available. In other words, when there is less sunlight available, providing chlorophyll-building nutrition becomes MORE important, not less important.

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