Daylight hours during growing season for full sun

I always struggle with being too analytical about full sun vs part sun ect. when planting. I live in Western Washington state and we have long summer days but they are not terribly hot. When looking to extend my orchard on my 5 acre property, I am considering extending south towards my forest line. The only issue is, the forest line tress are very tall. This means that I need to keep some distance from the forest to keep light levels up.

For my full sun trees, I try to give 6+ hours of full, unobstructed sun. This is easily achievable, even very close to the forest during the longest days of the year but March and Sept may be only 3-4 hours due to the sun’s angle with filtered light the rest of the day.

Up until now, I’ve been trying to calculate 6+ hours for months from March to Sept, figuring that is when most photosynthesis is happening, but I’m wondering if I would be okay if 6+ hours on the longest day of the year, which may only be 4 or so on the March and Sept side of the year. I realize this is not an exact science. Also, I realize that things will “grow” fine in more shade than they will fruit fine. I’m also worried about vigorous weak growth, due to stretching to find the sun.

Being that my summers are not very hot, I’m sure Texas zone 8 would get much more fruit from a similar situation that Seattle zone 8. I have thought about adding some more shade tolerant elements into my orchard. I know Amelanchiar (which I have several), current, and most mid-sized shrubs will tolerate shade but fruit heavier in full sun.

Please let me know any thoughts you have on this topic.

I’m in the same boat wondering if at this time of year will 7 hours be enough for blueberries? You seem to have a good grasp of the consequences of shade on fruit production. I think if you just go with your gut your experiences will lead you in the right direction. Either way figured I’d give my two cents and hope someone with more experience will chime in

1 Like

Have you tried this website, to simulate the shadows?

(works outside EU to)

I explained how to use it in this topic

If you select the hight before placing points, they already all have that hight.

I would also consider placinbg earlier ripening fruits/varieties in the spots that get full sun mid summer but some shade from sep on.

I would also shy away from known biennial bearers. (flower development is mainly end of summer.)
Although the extra shade during flower bud development might also lessen the flower buds to an extent that you have less biennial bearing. I just don’t know. Might be worth an experiment :slight_smile:

1 Like

Tried it for USA instead of Europe

1 Like

@oscar that’s a nice set of guides you posted, unfortunately satellite images are taken before I cut down trees and moved fences around. I think I will just experiment maybe with some potted trees and bushes and see what work. So next year I’m sure with the guides and some experience I’ll have it all figured out, might just have more currants then I wanted

1 Like

I have used it some. I also use a live tool called Sun Surveyor. My landscape has changed a lot since we bought the house. The map programs have not updated since we’ve done some major clearing and building. The Sun Surveyor works very good to live view where the sun will be when standing in a location.

I have concerns as well about how much sunshine is enough sunshine. I’ve used the app Stellarium to know where the sun will be and how long it will shine depending on time of year… sounds similar to Sun Surveyor.

1 Like

I think these aps work well. I’ve noticed that Sun Surveyor hits right on where the sun is in the “Live View” so you can set it to any date and see where the sun would be during that day. One thing I’ve thought about is if it is a tree, the angle will change as the canopy grows so it will get more sun the higher it gets. Also the width of the canopy of a tree can be quite a bit more light than my 2’ diameter frame would get standing in a spot. I try to think about the mature tree and how much sun it will get rather than the little sapling I am installing.

From my research, there’s no clear line that you can call “full sun”, the term is shorthand for nursery catalogs so you know what can be planted where. If you tour an apple orchard you’ll see that each individual tree is heavily shaded by the other trees during the early and late hours of the day, so even there “full sun” doesn’t mean from sunrise to sunset, it’s more like the middle 2/3 of the day from overhead sun. That’s the ideal you’re measuring against, though.

In general, the more sun your trees get, the more yield you can expect, and the relationship is surprisingly linear. For a home grower, this means trees that get some shade need to be thinned more than trees that get sun, and they may self-thin to some degree. see this survey paper for example:


I have 25 10-year-old blueberry plants planted on a 1 acre clearing in an alder/cedar forest in Western Wa. Probably 7 hrs sun in summer, 4 hours in winter. Plants 4-5 ft tall and productive. This is blueberry growing region!

1 Like