How much sun do pines really need?

[Paradox]

The issues with my friends JBP raised some questions in my mind.

We always say pines and juniper need "full sun" or "lots of sun" but what does that mean exactly?

We know in summer, the sun is above the horizon at least 15 hours a day (at my latitude). This changes with the seasons and angle of the sun to the earth.

I know in my yard, my pines get the most hours in early to mid summer but spring and fall are lower because of seasonal changes.

So does full sun mean at least 12 hours? Can pines survive with 8 or even 4?

At what point is it best not to consider pines an option because you can't give them enough sun?

What is the minimum hours required for a pine bonsai to thrive in your experience?

Thoughts and discussion please?

 

[M. Frary]

Full sun means that the tree is getting all of the light it puts out without shade.
Partial sun means dappled shade like for Japanese maples.
Shade means no sun or very little like what moss grows in.
Duration would be the length of time.
Where I live full sun means the trees are sitting out in it all day. It isn't as intense as it is further south.
For someone in Arizona the sun is more brutal so they may only want their full sun plants to only get it mornings and evenings when there is less chance of roasting.
At least this is how I see it.

 

[Brian Van Fleet]

Almost impossible to quantify, because of other variables at work; altitude, humidity, day length. Here's my gut check:

4-6 hours a day: fungal and insect problems will probably occur within a year. Soil won't dry quickly enough, and outer needles will grow stupid long, completely shading out interior growth. This means by fall, the weakened interior buds are really shaded out, and will become less viable. Add that to long, diseased needles, and you won't have much to work with the next year.

6-8 hours a day, probably less fungal issues, may still have problems getting the soil moisture right. Needles are shorter, but you'll have to work hard to keep the interior buds viable. Shady side will weaken within a couple years.

I keep my pines in full sun, which is sun shining on the tree from sunrise until late in the afternoon. They get approximately 10 hours a day right now, slightly more in the peak of summer. I do everything I can to site my pines where there is no shade. This new garden is more exposed, and windier, so I am glad when the house shades out the deciduous side of the garden around 4:00 PM, but the pines get all the sun I have to offer; Zuisho included.

 

[Dav4]

I give my pines (and junipers) as much sun as my back yard allows, which is only 4-5 hours a day, with dappled, high shade otherwise. Overall, I'd say they remain fairly healthy despite the relatively inadequate amount of sun they receive. I suspect the fact that the sun they receive occurs between 10:30 AM and 3:30 PM in my N GA location plays a huge role in this, as we're talking full on southern mid day sun...that's got to be worth an extra hour or two of northern full sun exposure. Also, my trees stay on the benches for about 50 weeks a year, receiving a fair amount of sun during this "dormant" period, but probably remain more metabolically active then trees in colder climates. Anyway, they get just enough sun to remain healthy, but I wish they could bet more. Plans are in the works to get rid of a few more trees to improve exposure...hopefully sooner then later.

 

[sorce]

You all know I have east wall plants and west wall.

I have a theory, that morning sun is considerably better than evening sun, in that, the tree in such heat, can not utilize the light as efficiently.

My Mugo is in the west. Vance says it needs more sun.

My elms burn in The west.

The sun exsposurr duration, is almost equal.

Sorce

 

[aml1014]

I agree with sorce and bvf it all has to do with other variables that can not be calculated in a way that you ask. In my climate of course my black pines will take the sum cause they're tough, but I have a silveray korean pine that will roast in the matter of one day in the same spot as the black pines (made my mistake once, never again, so no that tree gets about 4 hours of morning sun then 50percent shade the rest of the day and it seems to be very healthy now. Climate and species always play a massive role in placement.

 

[0soyoung]

I have a theory, that morning sun is considerably better than evening sun, in that, the tree in such heat, can not utilize the light as efficiently.

In the course of any given day, the relative humidity will be higher in the morning and lowest about mid-afternoon. Mid-afternoon (about 3pm) is when the tree is subject to the maximum hydraulic stress! The stomata may be completely closed, in which case little, of any, photosynthesis is going on = so you are right, Source.

 

[sorce]

Source

 

[LanceMac10]

As much sun as I can find and move to it daily.....
Akadama, lava, pumice....water all day if you like, drainage is good, needles as long as your arm
Easy with the fert and water in spring.....
I'm wondering if yellowy needles mean wet soil or fert deficiency...
Still think it is wet roots....





confused yet.....?

 

[fourteener]

I believe the typical recommendation for any full sun plant is more than 6 hours. In my yard my pines get sun from sun-up to sun-down. After 6 hours there are probably some questions about your temps and how warm your pots are getting. Too many variables. As much as you can give them without heating up your pots too much is my semi-non-answer.

 

[Leo in N E Illinois]

Enough sun to grow tomatoes well is about the minimum that pines need, they would like more sun than tomatoes. If your yard is too shady for tomatoes, and roses, it is too shady for pines.

 

[quietobserver]

Thought I’d bump this thread as I’ve been doing quite a bit of reading on the subject an while limited, this has been helpful. After 15+ years of bonsai I’d really like to diversify into JBP & JWP but I’m uncertain if my new(er) yard gets enough direct sun.

 

[ShadyStump]

Seems a discussion worth continuing long enough for others to read and learn also.

I've not had much luck with pines (or any conifer for that matter) so far, but I'll add that altitude can play a major part in what does or doesn't count as full vs partial sun.
Here in Colorado it's considered good practice to use sunscreen when you go up to the high county, even if you usually don't bother, or the weather is supposed to be overcast. The joke during winters is this is the only place in the world you can get a sunburn on top of your frostbite. There is literally less atmosphere to filter out the light, hold temperature, or hold moisture. Add that to more than twice the sunny days in a year than the national average, and full sun is essentially optional for many plants in these parts.
Even the most sun tolerant trees, I've noticed, often benefit from protection from the hot afternoon soon, like @sorce posited before. The southwestern portions of trees are often dead from localized winter temperature extremes. A harsh freeze over night followed by bright afternoon sun the next day performs the same actions as dragging a tree from outside in the snow to inside in the window, and then back again.
@Leo in N E Illinois compared to the demands of roses and tomatoes seven years ago ( wow, talk about necroposting lol) and here they are routinely grown in dappled if not full shade; still not ideal for them, even here, but more than adequate. (Never your peppers, though. They don't get spicy if they don't get sunburnt )

Compare these conditions with when I was stationed in Washington state, and full sun essentially means two weeks in July, and a sunburn is considered a badge of honor.
So like many other factors in bonsai, climate is key.

 

[MaciekA]

Thought I’d bump this thread as I’ve been doing quite a bit of reading on the subject an while limited, this has been helpful. After 15+ years of bonsai I’d really like to diversify into JBP & JWP but I’m uncertain if my new(er) yard gets enough direct sun.

I agree with the very ancient posts in here in that there is a "gradient" of behavior from weak to strong depending on light. I see some noticeable differences between pines that sit in a corner that gets an extra hour or two after the others have plunged into shade. I'm also next to some woods where you can see an assortment of pines (notably contorta + ponderosa) in different ages / conditions and the more shaded ones are very obviously weak and have sparse looking appearance while high-sun locations yield shiny healthy needles that look like almost LEGO-plastic appearance, juicy whispy bud development, much longer internodes.

If you have doubts about this, you could test your conditions using seedlings of either JBP or your more local loblolly and use them as a biological light meter. If by the end of the season you see deep color, beautifully shiny, almost plasticky firm needles, you probably have enough sun for JBP. While you're at it, stick to best practices for enabling high transpiration -- pond basket or colander for a container, zero organic components in your soil, coarse pumice or similar particle, and small soil volume. High oxygen availability in your container, strong drainage, and a small soil mass to draw water from give your pine a fighting chance to do well in high humidity summers and to overcome a slight disadvantage in light exposure, if it turns out you don't have enough light. This will give you a known-good platform to determine if your grow space works for pine much better than an already-mature JWP or similar.

Also @ShadyStump makes a very important point about elevation. In Germantown TN, you're basically for all intents and purposes at sea level, so if you have doubts about enough sun exposure in your yard, stick to coastal or low elevation pine species which have not necessarily evolved a thicker cuticle for the high elevation / alpine photon firehose. So for now, maybe avoid species like JWP and bristlecone pine in favor of JBP, loblolly, shore pine, etc.

If in the most intense part of the growing season you have at least a couple exposure hours "centered around" noon you should be fine, but give yourself the best chance by choosing a fast-transpiring pine species and a fast-transpiring potting configuration.

 

[Ply]

As much sun as I can find and move to it daily.....
Akadama, lava, pumice....water all day if you like, drainage is good, needles as long as your arm
Easy with the fert and water in spring.....
I'm wondering if yellowy needles mean wet soil or fert deficiency...
Still think it is wet roots....

View attachment 82718

View attachment 82719

confused yet.....?

Ever figure out what was the cause?

 

[LanceMac10]

Ever figure out what was the cause?

Not sure if the original poster resolved the issue. My photos didn't show yellowing of needles, but have seen yellowing. Absolutely wet roots from two years of growth. New roots circled the bottom of the pot and lay in too much moisture......

Lance's JBP....

june 1 '18

www.bonsainut.com

Did have some yellowing prior to this re-pot......two layers of circling roots. Plenty of healthy "myc".....

 

[WNC Bonsai]

My pines get about 6-8 hours per day in summer and seem to be doing well. Nice dark green needles and no fungus issues. Of course that does require moving them in mid-afternoon to keep them in the sun. The trees in my yard keep getting taller and thicker and SWMBO will not allow me to take corrective action.

 

[Mike Corazzi]

My pines get about 6-8 hours per day in summer and seem to be doing well. Nice dark green needles and no fungus issues. Of course that does require moving them in mid-afternoon to keep them in the sun. The trees in my yard keep getting taller and thicker and SWMBO will not allow me to take corrective action.

SWMBO ?

 

[Zerobear]

Almost impossible to quantify, because of other variables at work; altitude, humidity, day length. Here's my gut check:

4-6 hours a day: fungal and insect problems will probably occur within a year. Soil won't dry quickly enough, and outer needles will grow stupid long, completely shading out interior growth. This means by fall, the weakened interior buds are really shaded out, and will become less viable. Add that to long, diseased needles, and you won't have much to work with the next year.

6-8 hours a day, probably less fungal issues, may still have problems getting the soil moisture right. Needles are shorter, but you'll have to work hard to keep the interior buds viable. Shady side will weaken within a couple years.

I keep my pines in full sun, which is sun shining on the tree from sunrise until late in the afternoon. They get approximately 10 hours a day right now, slightly more in the peak of summer. I do everything I can to site my pines where there is no shade. This new garden is more exposed, and windier, so I am glad when the house shades out the deciduous side of the garden around 4:00 PM, but the pines get all the sun I have to offer; Zuisho included.

Full sun to me means unprotected exposure during at least 4 hours of either first light or end of day light. In our area, full sun during the middle of the day can be brutal and may keep some plants (like hornbeam) from thriving, or actually kill them. I think that is probably the heat during the middle of the day and angle of the sun in our area (8a), more than the actual sun. IMO, if you can get 4 hours of direct sun, that will be sufficient for the plant to thrive if it is a full sun plant. In 8a, junipers seem to be able to take the most direct, hottest exposure we have, and are planted beside the city streets in parking lot beds and in roadway median flower beds. Any plant that survives planting in the strip separating automobile traffic likely loves the direct sun. Not your question, but there are excellent bonsai in many roadway, and parking lot beds in my area. Cars and sun exposure seem to accomplish a lot of the same rugged looks that growing on the diff side of a mountain accomplishes. There is only the problems you will encounter when the police discover you in the middle of the road with a shovel harvesting a nice juniper for your collection.

 

[WNC Bonsai]

SWMBO ?

She Who Must Be Obeyed