That's pretty much the question. If I have apples or cherries or strawberries or blueberries or other fruits or vegetables that require full sun, and the plants get 6 or so hours or sun, would they produce more fruit if they got 8, 10, 12, or 14 hours of sun? For full sun fruiting plants, is more light always (or usually) better?

I think the extra sun might be too much in some climates. It would depend upon where the fruit is being grown.

porkpal said: I think the extra sun might be too much in some climates. It would depend upon where the fruit is being grown.

Interesting! I can give a specific example. I see an apple tree with a tag that reminds to make sure it is in full sun for at least 6 hours. If I have a choice to plant, in Virginia, in a place in the yard that gets 6 hours of sun or another spot that gets 10 hours of sun, what could I expect the difference to be between both trees?

Does more sunlight increase plant growth?

Light is an essential factor in maintaining plants. The rate of growth and length of time a plant remains active is dependent on the amount of light it receives. Light energy is used in photosynthesis, the plant's most basic metabolic process.

https://aggie-horticulture.tam...

I also found this question intriguing and spent some time researching but, like RpR's linked article, I couldn't find one that specifically addressed the question "is more light always better?" which I think might be better framed as "is there an optimal duration of sun exposure for optimal fruit production?" My conclusion is that there are too many environmental variables to make a general statement and it also varies from plant to plant. One article I read about figs (sorry, didn't copy it) noted that different cultivars had different light requirements.

Many articles stated that too much sun can be detrimental (as those of us who grow tomatoes in hot regions know very well) but beyond that I think it is entirely variable depending on what you're growing

Admittedly, I didn't spend a huge amount of time on this. I think you might need to research each specific tree species and cultivar.

Excellent question

And where you're growing it.

Thanks for the thoughts so far.

It seems to be a question without a clear answer, and/or not a simple answer. So that is not very satisfying to me!

So, for example, if I'm looking for a place to plant my strawberries next year, or two apple trees, I want to know whether it is worth the extra effort to find a spot that will give 8-10 hours of sunlight; or if there is a convenient and easy to plant spot that gives 6-7 hours of sunlight, whether the result will be the same either way.

Hi MadPlanter,
Welcome to gardening. As you are discovering, there are often no clear answers to a gardening question. It can be pretty frustrating. But the truth is what works well for one person in one area often won't work so well in another area.

I also don't have a definitive answer for you, just some anecdotal observations. And keep in mind I live in screaming hot Arizona which is very different from Virginia.
However... when I planted my apple trees 2 years ago all my research indicated was that the apples themselves must have direct sunlight in order to ripen. That I should prune my trees to thin out a whole lot of branches and leaves to allow the sunlight to penetrate to the fruit. So I did that. One tree is in full sun and one is in part shade/part sun all day long. The tree in part shade did very well. I got a nice little crop of Gala apples this year. But all the Fuji apples in full sun got sunburned on the south sides of the fruit. So the advice they gave me didn't work so well for me here. I would imagine that 6 hours of sun would be fine especially because the trees produce a whole lot more fruit then they are capable of growing to full size and you have to thin most of them out when they are tiny.

My cherry trees are only 3 years old and haven't started producing yet.

I have 3 kinds of strawberries in 3 different beds. They all wilted very quickly on hot days and did much better when I gave them all some shade. Then they produced a lot more. They don't seem to need so much sun.

Sorry I couldn't be more help.
Debbie

I'm thinking the answer might not be clear, and that depending where I look, I might see different opinions.

SedonaDebbie said: Hi MadPlanter,
Welcome to gardening. As you are discovering, there are often no clear answers to a gardening question. It can be pretty frustrating. But the truth is what works well for one person in one area often won't work so well in another area.

I also don't have a definitive answer for you, just some anecdotal observations. And keep in mind I live in screaming hot Arizona which is very different from Virginia.
However... when I planted my apple trees 2 years ago all my research indicated was that the apples themselves must have direct sunlight in order to ripen. That I should prune my trees to thin out a whole lot of branches and leaves to allow the sunlight to penetrate to the fruit. So I did that. One tree is in full sun and one is in part shade/part sun all day long. The tree in part shade did very well. I got a nice little crop of Gala apples this year. But all the Fuji apples in full sun got sunburned on the south sides of the fruit. So the advice they gave me didn't work so well for me here. I would imagine that 6 hours of sun would be fine especially because the trees produce a whole lot more fruit then they are capable of growing to full size and you have to thin most of them out when they are tiny.

My cherry trees are only 3 years old and haven't started producing yet.

I have 3 kinds of strawberries in 3 different beds. They all wilted very quickly on hot days and did much better when I gave them all some shade. Then they produced a lot more. They don't seem to need so much sun.

Sorry I couldn't be more help.
Debbie

Debbie:

Thanks for contributing. I think you are right—we probably will never know for sure what we could have done to get the optimal yield for our efforts.

Your experience was very helpful.

Think of a plant's relationship with light as being a pair of bookends, with one bookend being the plant's LCP (light compensation point) and the other being light saturation point. The LCP varies by species and occurs when there is enough light to synthesize (via photosynthesis) exactly the same amount of food (sugar/ glucose) as the plant 'burns' during the respiration phase. Plants need to produce more energy than they use to keep their systems and processes balanced and orderly in order to grow and produce fruit. Just as a flashlight "dies" when the energy stored in its batteries is depleted, plants unable to create at least as much energy as they use during respiration will die unless the trend can be reversed by amending cultural conditions to enable creation of more food/energy.

True growth is measured by the plant's increase in dry mass. When the amount of food/energy created during photosynthesis is the same as that burned during respiration are the same, the formation and consumption of organic matter are equal, and dry matter cannot be accumulated. The plant might show conspicuous branch/stem extension and perhaps some new leaves/branches) but if plants are shedding as much dry mass as they are creating, they are not "growing" in the true sense of the word.

The other half of the 'bookend' pair, as mentioned, is the light saturation point. For any given plant and light wavelength, the rate of photosynthesis increases until reaching the light saturation point, at which the photosynthetic rate reaches its maximum (flatlines), and where additional photo photo load produces no increase in or a negative effect on photosynthesis.

Also in play is how the plant is genetically programmed to supply its various energy sinks with food/energy. An energy sink is simply a part of the plant that requires energy input, and all energy sinks are not equal, they have a predictable pecking order. When plant parts call for food/energy, the primary allocation goes to respiratory function, i.e. to maintenance of living tissues, then, to production of fine roots, followed by flower and seed/fruit production, then primary growth (extension of both roots and shoots), then secondary growth (thickening), and finally, the synthesis of defensive chemicals. From this, we can see that the plant must have created enough energy to satisfy the energy needs of its living tissues and growth of new roots or replacement of roots damaged or killed by poor conditions in the rhizosphere before it can produce reproductive parts (blooms, fruit/ seeds).

Al

The above is very interesting. I guess it also demonstrates that this data is not easily available, and perhaps is much opinion as it is science. At the end of the day, it still is not easy to determine whether a particular strawberry variety would do better in 7, 8, 9, or 10 hours of sunlight, and if so how much better. A lot of gardening feels like partially informed guessing! Lol

I would not say opinion and guessing as much as experimentation and observation. Problem is, it's a whole lot easier to relocate strawberries than apple trees once you learn they need more shade. Like Debbie, with experience I've learned that my high altitude western desert sun behaves entirely differently than sun in other regions at sea level, so I plant accordingly: most crops go in half-day shade. That probably wouldn't work in your climate and location.

I think befriending growers in your immediate region is your best bet.

And part of Debbie's problem is fuji apples. I am surrounded by apple orchards. When fujis were first introduced, the farmers went crazy planting them. Fujis taste great but are impossible to grow. Now everyone has moved on to honey crisps and pink ladies. I think the fujis have moved north to Washington state

My apples are in full all day but my strawberries are in the shade.

The data re what constitutes the perfect light intensity and duration is not readily available because the number of variables involved (things like light quality, duration, intensity, color temperature, air quality, CO2 availability, et al) all have an impact on how much usable light there is and/or how much can be turned into food. A precise answer would require that all variables be taken into account, and that would be difficult enough in a controlled environment, never mind our backyards.

Al

Alao keep in mind, if part of your plot has limited hours of sun, whatever limits that (tree shadows, house shadows) can limit MORE in spring, fall as tha sun is lower and shadows longer. So may affect the soil warmth and give you less sun Than if you're looking at 6 hours in midsummer.

Perhaps experiment with the strawberries and plant them in several different locations/sun exposures. Next year you will know what works best for them. I would guess that most apples would do well with as much sun as you can give them.

There are other factors that have much more of an impact on how much fruit you will get than the amount of sun. For example, whether there is adequate pollination and whether the variety you have chosen is suitable for the number of chill hours in your location. I would worry about those things much more than a few hours more or less of sun.

Not necessary. Strawberries, for instance are said to be a "short-day fruit!" They flourish with around 4-6 hours of sunshine per day, and that is one reason major strawberry growers are located along California coastal regions like Watsonville, Santa Maria, Oxnard, Salinas and Orange County.

This may be true as all plants undergo photosynthesis to manufacture food for all the plants functions like making leaves ,flowers ,fruit and seeds .So the sunlight provides the energy needed for these processes to occur .So yes I do think that one can say more sunlight like the normal rays and not the very direct intense light is benefical in food manufacture for the plants wellbeing .