Daytime & Nighttime temps in sunroom

wendync(7b)November 8, 2012

I have a question about safe temperature changes in my sun room and it's affect on my houseplants in there. Because of the nature of the room, on a sunny day, it is often 80 degrees in the sunroom during the day.

However, the lack of insulation means that after dark, the temps drop pretty drastically. I have a space heater out there and I have been maintaining the room at 60 degrees at night.

I'm a little concerned that this 20 degree temperature change could be stressful for the plants. I know the more heat that I use in that room, the drier the air will become, so I have just purchased a humidifier to put near the plants. Thoughts on this? Should I try to increase the temps at night or do you think they will be ok?

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Hi Wendy,

What type of plants are in the sunroom? Tropicals, succulents?

Heatwise, 'gas, etc.' During the day 68-72F is fine. A 10-15 degree drop at night is perfect...20 degrees won't harm your plants, unless 'x' plant is extremely sensitive to chills.

The best advice I have is, water in the morning or early afternoon. Especially succulents.

Investing in a humidifer was a good idea.

I wouldn't increase night temps, but maybe someone here disagrees...Toni

    Bookmark   November 9, 2012 at 10:48AM
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Wendy,, sorry, I should have been more specific.

You said the sun room is 80 during sunny days..
I mentioned 70-72...

80F degrees due to sunlight is fine, natural. Toni

    Bookmark   November 9, 2012 at 10:51AM
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tapla (mid-MI z5b-6a)

I'd say that 65* nights & 80* days is great. 60* isn't too far off the mark, but I think that's a good number to consider as the lower limit for best results. Warm air has more space between the molecules, so as air temperature increases, relative humidity decreases, unless there is a source of additional humidity to fill the gaps between air molecules that increase as temperatures rise. What dries the air in our homes when the furnace comes on has nothing to do with the furnace itself. What happens is, cool air from the outdoors makes its way into our homes. This air has little moisture in it, so when it gets heated, it greedily sucks up moisture. When it leaves our homes through whatever source that allows its escape, it carries moisture from our homes with it. It's then replaced by dry, cool air making its way inside, and the cycle continues. Often, in older homes that don't use outside make-up air for combustion in the water heaters & furnace, lots of moisture laden air goes out the vent stack or flue, which increases the cycle of moist air exiting and dry air entering. After the science lesson, I should say that the humidifier is a decidedly good idea, and something between 50-60% should be a favorable setting if it doesn't cause condensation to form on the walls or inside glass surfaces of the room.


    Bookmark   November 9, 2012 at 10:55AM
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Tiffany, purpleinopp GardenWeb, Z8b Opp, AL

A temperature swing like that in nature, about 20 degrees, is normal most places, most nights, and often a bigger gap than that. It's hard to say if your specific plants would like the same conditions as anyone else might describe though.

The room where all of my plants spent the past few winters gets down to around 55 if it's really cold at night. Might get to 65 in the daytime.

The last winter I was in OH, my plants lived in an unheated room that would get down to about 45 but had windows on 2 sides and was sunny and much warmer during the day. Wow we saved a lot of money when we realized what a sieve that room was and closed the vent and the door.

MIL just staples plastic over the screen of her back porch and uses no additional heat except a light bulb if she thinks it's necessary at night. She has about 50 different plants but more actual pots, many identical to mine as we've traded about everything possible that either wanted. Last winter she had several Coleus stay alive in there, so we can be sure it didn't get to a frost in there although it dipped below that point outside many times.

My neighbor who has plants that are older than I am uses an unheated shed that's a very dark color and does have some insulation and windows, so I'm sure warm and sunny in there by afternoon. She said she turns on a space heater on its' lowest setting on nights below 25.

If you have some kind of risers or stands for any plants sitting directly on the floor, even a couple inches that would prevent the pots from making contact with the ground, which is usually much colder than the ambient room temperature, the plants might appreciate that. A room that's 68 might read 52 if you lay a thermometer right on the floor.

You plants might get a lot of benefit running a little fan for a few minutes a couple times a day, or as much as you feel reasonable.

In your room that doesn't get dry air from central heat/furnace, and having multiple plants, the humidity would not be as much of a concern for your room as one being kept 30-40-50- degrees warmer inside than out with a central system. It may be more humid in there than you think. It's definitely humid in here, condensation on the windows in the morning, we don't run the central heat.

    Bookmark   November 9, 2012 at 11:26AM
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These are the plants out there:

Pachira Aquatica

Angelwing Begonias

Dracaena "Lime Light"

Red Aglonema

Mimosa Pudica (Sensitive plant)

Philodendron "Prince of Orange"

Jasmine Angelwing

Jasmine "Maid of Orleans"

Jasmine Brazillian Red Mandevilla

Coffee Arabica (very small)


Mini Orchid

Goldfish Plant (very small)

Columnea "Carnival" (very small)

Lemon, Lime trees(in same pot)


Parsley Aralia

Lipstick Plant "Black Pagoda"

Olive tree(very small)

Dwarf Banana(very small)


Are any of these particularly sensitive to temps? The temps in my area have started to get near freezing some nights(hence the space heater).

    Bookmark   November 9, 2012 at 12:44PM
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Tiffany, purpleinopp GardenWeb, Z8b Opp, AL

What a nice collection! Feel free to put up some pics if you feel like it. We love plant porn!

Are you asking if these plants are sensitive to the conditions you described at the top of the thread? (60/80) Or if these would be OK with some of the more extreme conditions that have been described?

    Bookmark   November 10, 2012 at 8:12AM
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