Why do plants need light?

Trees in a forest

Without the light from the sun no form of life could exist. The plants that we know and all those that once inhabited the Earth, evolved from a bacterium that was capable of using solar energy to make food. This process, over time, would not only help them to survive and grow, but also allow animals to explore and, when the time comes, colonize those habitats where the climate was pleasant enough for them.

Thus, Why do plants need light? The short answer would be: to live, but we are going to expand a little more and we are going to know why it is convenient to know in advance the appropriate location for the plant that we want to have in the patio or garden.

They need light to feed

Flowering plants

Plant roots are elements that absorb water and the nutrients from the soil that are dissolved in it. These are carried to the aerial part by the stems and branches until they reach the leaves, which are the food factories of plant beings.

The leaves, which absorb carbon dioxide (CO2), can make food (starches and sugars) thanks to the energy of the sun in a process known as photosynthesis. During this process oxygen (O2) is released which is released into the atmosphere.

Plant diversity

There is a great diversity of plants: trees, palms, climbing plants, flowers, bulbous…. As a general rule, those that are very large (six meters or more) are sunny and the small ones are shade or semi-shade. However, those that produce flowers, as well as horticultural ones, have to be in a sunny exhibition.

Depending on the habitat and climate conditions, each species has evolved to adapt as much as possible to the place where it has lived. Thus, shade plants tend to have large leaves and a more intense green color than sun plants. In this way, the first they can make the most of the little light that reaches them, while the latter is enough to have small leaves to be more exposed.

The seasons of the year

Mammillaria dixanthocentron cactus

As the planet Earth rotates and moves away or closer to the Sun, the hours of light decrease or increase. During the Summer Solstice (June 20 or 21 in the Northern Hemisphere, and December 20 or 21 in the Southern Hemisphere), the day will have a greater number of hours of light, while in Winter Solstice (December 20 or 21 in the Northern Hemisphere, June 20 or 21 in the Southern Hemisphere), the day will have fewer hours / light.

All this directly influences the plants. During the summer, the Sun is, from our perspective, very high on the horizon, and its rays arrive more direct, which is why the temperatures are higher than in the rest of the year; On the other hand, in winter it is very low, so its rays arrive much more inclined and weaker.

In the polar and tropical regions there are hardly any significant changes throughout the year. At the poles the differences in the length of the day are greater, while in the tropics they are smaller, but with regard to the maximum and minimum temperatures they remain more or less stable as the months go by.

Choosing the right orientation

North or east facing location

In this area we have to put those plants that resist the cool / cold better, as they will have few hours of light during the day. For example, arces, horticultural like chard or lettuces, conifers, as well as those plants that we know are from cold climates.

South facing location

In this area we have to put those who do not like low temperatures too much. Indoor plants that are brought outside during spring and summer should be oriented to the south, but protecting them from direct sun as the leaves could burn.

But it is also the right place for palm trees, cactus and crass, horticultural like courgettes o peppers, and for plants with caudex such as Desert rose.

West facing location

It is the most successful location. Here you can have all kinds of plantsBoth the tropical ones that we have taken to enjoy on the patio, as well as the less sensitive ones. In fact, if you intend to have your own garden, if you orient it towards the west you can be sure that the plants will grow receiving the amount of light they need.

It is highly advisable to put in this location those that come from the greenhouse but are species that can withstand the conditions of our area well in spring. For example, Cycas They are usually sold as an indoor plant, but in reality they are plants that tolerate frosts down to -11ºC without problems. Whenever you have doubts, do not hesitate to contact us 🙂.

Gallardia in bloom

Without sunlight the planet would look very different.


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