If you Google full sun, you'll find it defined as 6 full hours of direct sun. One way to find the areas of your property that are full/part sun vs. shade is on the summer solstice, June 21 (longest day of the year). I created a simple chart and divided my garden into 10 seperate areas, then made a note each hour from 7 a.m. to 7 p.m. where there was sun/part sun/part shade/shade in each area.

Do plants require fewer hours of sun in hot climates than in more temperate ones?

Hopefully someone in your zone will comment on your question but I would guess the answer is yes. Six hours of direct sun in northern CT isn't as intense as the same number of hours in your zone.

when i did roses.. 8 hours was considered full sun ... some here suggest only six ...

so ... in other words.. a rose need 8 hours of sun.. to produce the energy .. to be vigorous enough to make those huge flowers ..

if you planted one in less sun .... you would get less flowers.. and probably smaller flowers .. decreasing with the level of light ...

and.. of course ... dusk and dawn sun is weak ... so if that is all available.. it would not be great ...

that is just about producing the energy/food it needs ...

with me so far ...

now.. as you suspect... sun in the heat of the day ... high noon thru 4 ... plus more since you are so far south ... is not a sun issue ...

that is more about whether any given plant.. can pump enough water to be able to bear the heat ... most plants perspire.. or sweat ... and if in full sun.. in high heat.. they will wilt ... but that is a soil/water issue .. more than a sun tolerant plants ability to take the sun ... [though of course, if you throw a shade plant in sun .... it will sun burn .. which is a sun issue ..

all that said.. the only option to full sun is called EITHER .... part shade .. or part sun ...

so that is the end of the lesson ... but without you providing us a list of suggested plants.. its really hard to give you specific info on where to plant them ...

a good rule of thumb.. is to protect anything from the hottest part of the day ... IF YOU CAN ... while still getting them enough sun ... so they can tolerate the water and heat issues ... rather than the sun specifically ...

hope that gives you a better idea of what you are dealing with

ken

Posted by ken, "without you providing us a list of suggested plants.. its really hard to give you specific info on where to plant them"
My question was general, so thank you gardenweed and ken for your general answers.
Now, since you asked, more specifically, at the moment I'm looking for spots to plant roses, pineapple, basil, tomatoes, peppers, and bunching onions. You might not think of all of these as perennials, but in my area they will over-winter if we don't get a freeze. So I need to consider winter sun as well as summer. That's why I posted on this forum.

veggies.. full blistering sun all day long.. improve the soil to add water holding ability .. or mulch heavily to retain water ....

and try to drown them while insuring proper drainage.. they arent swamp plants ...... they need all the power they can get to make the produce ...

roses ... just about the same ..

i really think PROPER WATERING will be your biggest hurdle ...

ken

I do not live in Florida but I travel and audit facilities in different climates Florida being one of them. They grow their roses in 3 hrs of afternoon sun because the sun is so strong they did not produce. Sun in zone 5 and zone 9 is very different. The areas are close to Miami that I know plant their roses in part shade.

You be the judge of how close the Miami area is to you and if your sun is as strong as that area. Florida is a big state.

My sister gardens in Georgia moved from the north and thought she had to grow her roses in the 6-8 hrs of sun. They cooked and died. She replaced her beloved roses and planted them in the back yard that gets 4 hrs of sun and they are blooming and doing better.

To the OP, may I also recommend that when selecting a full sun location for your plants, try to find an area that gets afternoon shade as well. Many plants prefer full sun, but will wilt in the heat of the afternoon sun.

gardenweed is correct - 'full sun' is defined as 6 (or more) hours, regardless of time of year. And yes, it does make a difference on siting as to where you are located. Many plants that tolerate or even demand full sun in more northerly or less summer heat climates than yours would appreciate some relief from that sun/heat in the primary growing season.

It is probably best to research the individual plants and their tolerances/preferences. For example, tomatoes stop setting blooms and producing when air and soil temperatures are too high (in excess of 85F) and basil will bolt in hot temperatures. While both of these are considered full sun plants, they would obviously benefit from some shade or cooling period in the hottest part of your summer. Early day/morning sun and afternoon shade is likely close to ideal for your area.

I'm in southern AL (still considerably north of you) & there are roses all over the area in all types of situations, even mostly-shade and dappled-sun-only spots. The bank across the street has several knockout roses up against the building on the north side under an eave. They are blooming now and look very healthy. Take a drive around your neighborhood/area and see what's going on in well-established gardens and parks.

The basil & peppers can probably take and enjoy as much sun as you can give.

If i need 6 hours of sun for a garden spot. I get 4 hrs. from 8:00 to noon. If I get 2 hrs. in late afternoon does that qualify?

Technically, it is 6 or more hours of direct sun, with four of those hours occurring between 10:00AM and 2:00PM (strongest sun of the day). Of course, the sun is stronger the closer to the equator you get, so those farther south get more energy from the sun in the same time as those of us farther north. So, full sun in Maine is not the same as full sun in Florida. Some plants need afternoon shade in Florida but don't in Maine.

Generally speaking, I would discount the sun before 10AM at 1/2 and the sun after 5PM at 1/2, so every hour before 10 or after 5 counts as 1/2 hour of "full sun." I would not count anything within two hours of sunset/sunrise toward the total.

I grow many "full sun" plants in less than full sun conditions because I have no choice. These plants (for the most part) do fine with 4-5 hours of sun from 11AM until 4PM. It comes down to trial and error to really know what works. Places like Home Depot love to distill the requirements down to color-coded tags like 6+ hours=full sun, 3-4 hours=part sun etc., but really it isn't that simple. It does depend on your particular plant.

I have seen light measurement tools for sale for about $30 that will apparently tell you what sun exposure you have. I have no idea if they are accurate. Another thing to consider is that an area could be "half sun" in summer but nearly full shade in winter. So, if your plant flowers (or fruits) in early spring, you have to evaluate the exposure then (when it needs the energy) and not in the summer.

bobby69: I would not consider what you describe to be full sun.