Sunlight plays a very important role in plant growth, it’s important to get a general picture of how much sun your garden gets and avoid shady areas. Keeping this in mind, how much sunlight do plants actually need? What is the optimal amount of sunlight for the best growth possible?
About 8 hours of direct sunlight is optimal for plant growth and development. Growing plants in areas with less sun exposure is still possible, the minimum amount of sun needed is around 6 hours. Plants advised to grow in partially shady areas will only need about 2-4 hours of direct sunlight daily.
So, let’s first look at a couple of examples to get a general picture of which plants need how much sunlight.
Terminologies
When you talk about sun-exposure of plants there are a couple terms to remember, which help you to get a general idea of the plants’ needs for the
- Full sun: Plants need at least 6-8 hours of direct sunlight
- Part sun: Plants need 3-6 hours of direct sunlight
- Part shade: Plants need 3-6 hours of direct sunlight, but protection from afternoon sun
- Full shade: Plants need less than 3 hours of direct sunlight
Sunlight needs of various plants
| Plant | Sun needed | Notes |
| Mint | Full shade | One of the best plants to grow in shady areas |
| Ginger | Full shade | Like most root vegetables, Ginger can do with very little sun |
| Kale | Full shade | Like most green leafy vegetables, Kale thrives in shady areas |
| Dill | Full shade | There are also a couple of herbs with little need for sun |
| Broccoli | Part sun/shade | Full sun can cause Broccoli to grow too fast, ruining the taste |
| Cauliflower | Part sun/shade | Cauliflower faces the same problem as Broccoli in full sun |
| Beans | Part sun/shade | Beans normally like a lot of sun, but can burn easily. |
| Cabbage | Part sun/shade | Like most cold tempered plants Cabbage thrives in partly shaded areas |
| Radishes | Part sun/shade | Too much sun will cause radish to turn woody. |
| Tomatoes | Full sun | Tomatoes need a lot of sun to produce sweet fruits |
| Pepper | Full sun | Similar to tomatoes, peppers also need a lot of sun to ripen |
| Eggplant | Full sun | Eggplants need a lot of sun, in shade they will not produce any fruit |
| Cucumber | Full sun | |
| Watermelon | Full sun |
Why do plants need sunlight
After getting a good
In short, sunlight is the main source of energy for a plant and is required to perform photosynthesis. Plants use this energy to combine Carbon-dioxide from the air and water from the soil to produce their own food in form of carbohydrates.
This means once the plant lacks enough sunlight it will start to starve. Many plants will try to survive in conditions less them optimum for the plant, but will not produce much or any produce at all.
What happens if plants don’t get the right amount of sunlight
Plants will suffer if they do not get the right amount of sunlight on a daily basis. Both too much and too little sunlight will prevent your plants from thriving and reaching their full potential.
So, in short, your plants will either grow much less efficient or die, they are also more prone to loose competition against weed, giving you much more work for a plant which won’t produce a lot.
Effects of too much sun exposure
Too much sun can cause Plants to burn, killing the leaves and destroying the plant over time. Some plants are very sensitive to intense sunlight and need to be protected from afternoon sun.
These plants are also very likely to suffer great damage if too much sunlight is directly shining on its leaves.
However, plants do have natural protection against high sun exposure called Non-photochemical quenching (NPQ), a process in which the damage done by sunlight is greatly reduced. One side effect of this protection is stagnant growth, the plant stops to absorb any energy during and directly after the protection phase. This can cause limited growth when exposed to a lot of sunlight.
Effects of too little sun exposure
A lack of direct sunlight will cause the plant to “stretch” and try to reach for more sunlight. Spindly plants will produce much less because a lot of energy went into growing instead of producing fruit.
Plants also have adjusted to withstand a short period of time without any sunlight. This comes in handy if your plants normally grow in a sunny spot but are covered by a shadow for a couple days. Just like humans plants collect their excess energy in form of carbohydrates for later use.
Extended periods of little to no sunlight will kill the plant, except for some plants which adjusted to a lack of sunlight or fungi. In most cases, a plant will try to survive, but even if it does, you will not harvest anything from the said plant.
Getting a good understanding of your property’s sun exposure and mapping out the areas with good, and little sunlight is very important before starting a garden.
How to see if your plants get the optimum amount of sunlight
Keeping your plants in optimum sunlight is very important, but how do you know your plants are having a good time in the place they are growing? Here are some ways to tell apart if a plant has enough sunlight or is lacking a bit behind.
- Leaf color: Healthy and thriving plants have dark green leaves, this color is caused by the chlorophyll in the plant’s cells. A plant which lacks sunlight will have lighter leaves and a plant exposed to too much sun will turn yellowish or burn. Leaf color is the simplest way to get a good grasp of which plants are doing very good in your garden and which might need some support.
- Leaning: Leaning is a side-effect of the plant’s search for light. A plant will always try to reach for more light if it does not receive enough to thrive. This is especially found in indoor growing, as plants sometimes do not get enough energy out of artificial light and then start to reach for the natural source. Outdoors this can be caused by a shadow, once the shadow starts covering the plant and cutting off the supply of sunlight the plant will try to extend the exposure time by growing away from the shady area.
- Plant growth: Another way to figure out if your plants are doing well is looking at their growth. This is more of a process over time and will not give you an immediate answer, but nonetheless, it will provide a much clearer picture. The easiest way to see the lack of sunlight is by looking at spindly plants, this is a very obvious sign to show a lack of sun exposure. More subtle variations in plant growth or lack thereof have to be observed over a period of time, or by planting the same plant in multiple areas to have a comparison.
Tips to improve sun exposure of plants
A garden lacking enough sunlight can be improved in a couple easy ways, to provide a much better place for your plants to grow in.
- Crown thinning: One of the main causes for shady garden areas are trees. The crown of a tree can be thinned every 2-7 years and help the sunlight to reach your garden. It’s very important to keep the east and west side of your property very clear, light from these directions has the right intensity for plant growth and does not cause as much damage compared to afternoon sun from the south.
- Paint your fences and buildings white: White will reflect light off of its surface bouncing it back into your garden and onto your plants. While this improvement is very subtle it can help with very minor lack of sunlight. Similarly, a garden pond will act as a giant mirror and reflect light as well, giving your plants even more indirect light to work with.
- Grow from north to south: Should you plan to grow in rows, planting from north to south can help you to improve the overall sun exposure of your plants. During the afternoon the sun will be positioned in the south, and mostly shine directly downwards onto the whole plant. This is not the case during morning and evening sun, the light will come from one direction and only provide one side of the plant with sunlight. Growing from south to north makes sure that all the sides of the plant will receive sunlight throughout the day.
Related Questions
Do plants get sunlight through windows? Yes, plants do get sunlight through windows, but the light intensity is reduced. They will generally require more exposure when placed behind a window compared to outdoors.
Do plants need sunlight or just any light? Plants naturally adjusted to the wavelengths of the sun, making it the most efficient way to provide energy to the plant. Artificial growing lights mimic these wavelengths and can also provide a good amount of energy to the plant.
