mattie g
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How much sun do tomatoes *really* need?

Of course, we all know that tomatoes are said to require "full sun" exposure in order to produce as expected. And I've generally seen that "full sun" means 6-8 hours a day, if not more. But is this actually true?

I ask because our backyard is the only one in the entire subdivision that doesn't have 50-70' beeches, oaks, maples, etc. in it (previous owners must not have liked trees). However, there are plenty of huge trees surrounding us that shade some sections of the yard all day, and other sections for a good portion of the day. One of these latter sections is where we have the garden.

The garden gets anywhere from 8 hours or less sun per day, depending on exactly where you stand. Most of the tomatoes get around 6 hours - and some definitely less than that. But yet the plants are all relatively healthy (knock on wood) and are producing fruits and flowers. You also can't really distinguish between one of the plants that gets 7-8 hours and one that probably gets 5.5-6 hours of sun.

Any and all sun the garden gets is from approximately 8:00 am to 4:00 pm.

I'm thinking about planting in future years, and am really interested to know if I have to/should change things up much or not in order to maximize production. I have a fairly limited amount of space to work with, but can reposition stuff and/or re-prioritize as I go forward (with tomatoes and peppers being the two "must-haves" in my garden).
Last edited by mattie g on Mon Jul 11, 2011 11:33 am, edited 1 time in total.

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rainbowgardener
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Getting sun from 8 - 4 is plenty. I have the same trouble with trees around my growing areas. When I tried planting tomatoes in one of the shadier areas, I got a very visible result. There was a stairstep line of tomato plants with the smallest plants being closest to the tree and (within an 8' bed!) the ones farther away, with a little more sun being bigger. All of the plants lived and all produced some fruit, but the more sun they got, the bigger and more productive they were.

If you get even 6 hr a day of direct sun, they will probably be fine, especially since you are south of me, so presumably a bit hotter climate. Any less than that, they will be stunted and less productive. In farther south, very hot climates, tomatoes need protection from hot midday sun, so the hours of sun thing does vary with climate.

mattie g
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rainbowgardener wrote:Getting sun from 8 - 4 is plenty. I have the same trouble with trees around my growing areas. When I tried planting tomatoes in one of the shadier areas, I got a very visible result. There was a stairstep line of tomato plants with the smallest plants being closest to the tree and (within an 8' bed!) the ones farther away, with a little more sun being bigger. All of the plants lived and all produced some fruit, but the more sun they got, the bigger and more productive they were.

If you get even 6 hr a day of direct sun, they will probably be fine, especially since you are south of me, so presumably a bit hotter climate. Any less than that, they will be stunted and less productive. In farther south, very hot climates, tomatoes need protection from hot midday sun, so the hours of sun thing does vary with climate.
I was wondering about that.

You're right - we get good warmth down here from pretty much mid-April through late-September. Frosts are fairly rare past early-April and before mid- to late-October. Perhaps I do have the benefit of the generally warmer weather, which is why my plants are doing quite well (I've learned a lot since last year, which was a disaster as a first-time gardener!).

Another question: Is all sun created equal? That is, is morning sun better than midday sun or evening sun, or is midday sun better than morning sun, etc.?

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hendi_alex
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I planted four tomatoes at my sister in law's house. The plants are shaded by a fence as well as some scattered trees on the east. They are also shaded by large trees on the west. The plants get about three or four hours of direct sunlight and two or three hours of very weak indirect light. This appears to be approaching the limit as the vines are tall and a bit weak and have 6-10 tomatoes on each plant but look nothing at all like my plants that get at least half a day or all day sunlight at my home. So IMO 4 hours direct sunlight with a bit of indirect light will make the effort worth while with a modest harvest, but less would probably just give weak spindly plants with few or no full sized fruit to form.

mattie g
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hendi_alex wrote:I planted four tomatoes at my sister in law's house. The plants are shaded by a fence as well as some scattered trees on the east. They are also shaded by large trees on the west. The plants get about three or four hours of direct sunlight and two or three hours of very weak indirect light. This appears to be approaching the limit as the vines are tall and a bit weak and have 6-10 tomatoes on each plant but look nothing at all like my plants that get at least half a day or all day sunlight at my home. So IMO 4 hours direct sunlight with a bit of indirect light will make the effort worth while with a modest harvest, but less would probably just give weak spindly plants with few or no full sized fruit to form.
Interesting, and it really does make sense. The plants I have in around 6 hours or so are pretty robust, but of course I'm new at all of this and my "robust" might be someone else's "less-than-perfect." I also have some late transplants that are in even less sun, so it'll be an interesting study to see how they turn out.

Just for posterity's sake...the plants that are doing the best and get those 6-7 hours of sun per day are a Brandywine and a German Queen. Each is closing in on 6' tall with 10-15 tomatoes of varying sizes and plenty more flowers on them. I also have a containered Black Krim that's getting a little less sun than those two, but it's getting close to 5' now with about six decent fruit on it - it also just had two trusses that popped out five tomatoes each in the past week (this is a plant that [url=https://www.helpfulgardener.com/forum/viewtopic.php?t=37440]was damaged a few weeks ago[/url]). The two Romas are producing pretty well, with upwards of 30 fruit between the two of them right now.

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I tried growing in an area that has early morning shade. Receives 2+ hours of mid-morning and 1 hour of mid evening sun. Under a tall maple tree well shaded all day. Late evening house shade.
No tomatoes did not grow well. Next to nothing on fruit, and plants mostly died off.
My experience, 3 hours is not enough.
I can grow some beans, potatoes, green onion, and popcorn in this spot.

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Signal30
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Always remember you don't HAVE to put them in the ground. You can plant tomatoes in pots and put them anywhere you want.

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PunkRotten
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My tomatoes get about 4 hours tops direct sun and maybe 1-2 hours indirect. They been growing fine, growing crazy all over the place in fact. I got a good amount of fruits and flowers too. But I know they'd grow a lot better if they received more sun.


I think that the fruits ripen slower without the extra sun. Seems like I am waiting forever for some fruits to ripen.

mattie g
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PunkRotten wrote:My tomatoes get about 4 hours tops direct sun and maybe 1-2 hours indirect. They been growing fine, growing crazy all over the place in fact. I got a good amount of fruits and flowers too. But I know they'd grow a lot better if they received more sun.


I think that the fruits ripen slower without the extra sun. Seems like I am waiting forever for some fruits to ripen.
Sounds fairly similar to me. Mine get anywhere from four to seven hours per day, with most of that being direct sun in the morning to middle of the day. It's honestly like a rainforest in my neighbor's back yard, and there is NO sun that gets through that dense canopy come 3:00 pm or so.

I've been waiting a while, as well, though the Romas are starting to ripen pretty good. I've also harvested the first BK and first Brandywine that formed (both on the smaller side, though). And with the heat supposed to get pretty unbearable this week, I don't expect much ripening for the next six or seven days.

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thisgardener1
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There are a lot of factors that can determine the amount of sun your tomato plant needs. Tomato variety and weather condition are typical examples. But to cut the long story short, a Tomato plant needs as much sun as it can get - not the type that shines in the sahara desert.

imafan26
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If the light quality is good, people do grow tomatoes indoors. If you get 6-8 hours of sun it should be enough. If the tomatoes are grown in shadier conditions, they are taller and have longer internodes. With less sun you may have fewer fruit and if the sun is inadequate, you may only get vegetative growth. Longer days are better if you want more and larger fruit.

Where I live, there is lots of sun but since I do live in the tropics the sun is a lot stronger than someplace like Alaska. However, Alaska can grow larger fruits and vegetables than I ever could because they will have more hours of sun. My longest day is just under 14 hours and the shortest around 11 hours. Not much difference throughout the year, but the sun intensity does change. However, with the short hours of daylight, I cannot grow anything except Southern varieties of day length dependent plants with a lot of disease and heat resistance . I will not get the yields some people can get with things like peppers and cucumbers. Disease and pests will kill them off first. I get a good harvest and I can harvest longer, but things like giant tomatoes and pumpkins will never happen with a short day.

Temperature also plays a part. Some people have very short seasons of 120 days or less because of temperature considerations. I have a 365 day growing season. I could technically grow tomatoes year round if I grow the heat resistant ones. I can grow corn almost year round if I use a tropical corn that only needs about 12 hours of sun. However, if it is too cold, eggplant, and hot peppers will not set, shiso will bloom and die, and green onions will bloom.

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Gary350
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I have been growing tomatoes 42 years in TN, tomato plants suffer in hot summer sun. I plant my tomatoes so they get cool morning sun then shade from a large tree after lunch the hottest part of the day until dark. Our summer sky is 15% to 50% clouds 6 hours of cool morning partial sun tomatoes do good. Direct sun on plants after lunch hottest part of the day is about 30 degrees hotter than air temperature that is why a car setting in the sun will burn you if you touch it. I try to keep my tomato plants out of hot sun after lunch. I also space my plants 18" apart this crowds the plants enough they shade each other. I also plant several varieties of tomatoes no matter what weather does some plants will do better than others. Even though I do my best to keep plants out of direct sun after lunch plants suffer really bad starting about July 20 when it is so hot 98 to 100 until Sept. Plant varieties that can not take the heat either, slow down, stop producing, or die. Varieties that can take the heat slow down and survive the summer then do better in the cooler fall weather. I typically get about 40 lbs of tomatoes per plant. Frost kills our plants about Nov 7 all the green tomatoes go into the kitchen to ripen on their own.
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