Here are some pictures of the foil I bought.

I have no insight on the foil, but I do have a question about your pots. What color are they? The color of the pots can make a big difference in temperature. One method I have used in the past is layering pots with one pot inside a larger pot. The outer pot takes most of the heat and the air between the two pots acts as a buffer allowing the inner pot to gradually change temps.

As far as applying the foil, you can use masking tape or possibly a spray adhesive. They also have that foil-backed tape that is used with HVAC systems. Good luck.

Hi Mike,

I got a large number of black nursery pots (for free) a while back so most of my plants are in those. I have also read about the large pot method, but am limited in that I do not have much large pots, mostly smaller ones and I am on a budget so cannot really justify buying more. And would the adhesive on the tape melt in direct sun over time?

Thank you for the advice, I see you live in Florida. What edibles do you find grow well for you during this time? I've read lots of complaints about tomatoes not being able to take the summer heat.

Since your pots are black, you could get some cheap cans of white paint and paint the pots, that will make a difference. Also try shading the pots themselves. Circle them with rocks, sticks, other plants, whatever you can find that will keep the sun from hitting the pots directly. Also, try mulching the top of the soil. Use some sand or light colored wood chips and that will reduce how warm the soil itself gets, not to mention it will help the soil to retain moisture.

Wow, sounds like you have a good bit of stuff growing! We don't get as much rain as I'd like so far this summer but I understand what you mean about the humidity and wet foliage at night. If you grow tomatoes in the autumn wouldn't the dropping night temperatures cause problems for ripening fruit? I think when I first started gardening in my last year of high school (still in college, so fairly new myself) I tried some tomatoes in November so maybe it does work. And I grew some kale over the winter also, the pots had to be 2 gallons or less but they put out lots of leaves (my mum loves juicing) with no pest issues.

I'm limited by a student budget as it relates to buying paint, also read a thread on here where a guy did an experiment with 4 pots, two black and white one covered with foil and one uncovered of each, in full sun and the foil wrapped black one was cooler than the white uncovered one which is what piqued my interest. We have a large yard but very scant tree cover lol, I do have a papaya under a mango tree for shade though. And I started mulching my containers months ago as the tops were drying out too fast and I had to water too often, I use the locally abundant casuarina leaves which look like and function similar to pine needles. That's a really great tip :-)

Tomatoes like warm days and cool nights. Night temperatures need to drop to somewhere below 75F for the plants to set fruit. This can vary from one variety to another. My larger tomatoes, Monomahk's Hat, stopped setting fruit long before my cherry-sized ones which still set fruit on some of our cooler nights. I am not sure how low tomatoes can handle at night and still produce, though, but as I said, there are a few people on this forum who have kept their tomato plants growing right through winter. For autumn crops, I have been told you want to start seeds about now so that when those cooler nights do come, the plants are ready. Being that you are in the Bahamas, I am not sure how this would apply to you.
Another thing to look into are Subtropical Fruits and Veggies. There are a lot more options for edibles than are commonly thought of.
Foil would definitely keep the temperature down on your pots as the shiny side of the foil reflects light and heat (and alien mind-control rays). But be aware that that reflected light and heat has to go somewhere and if there are any other plants nearby, they will surely get fried. This could be a fun way to create an interesting pattern of crescent moon shaped sections of dead grass in the lawn. Another way to keep the foil on the pots is to simply fold the foil over the lip as you circle the pot and then crimp the two ends together after you cover the entire circumference. Or simply determine which side of the pot gets the most of the direct sun and fold one end over the lip while tucking the other end under the pot. The shady side of the pot doesn't really need to be foiled. Or crimp one end over the lip run the foil under the pot and back up the other side. Then make sure the foiled sides face east/west so the rising/setting sun hits the foil.

Thank you for the lengthy reply! I was mailed some Amish Paste seeds from a mother of a college friend in Tennessee recently and they're supposed to be one of the best for paste tomatoes and determinate in growth so I think I'll start some of those. We've no frost so growing over the winter here wouldn't be a problem I suppose, I remember when I first started I grew some corn in January.

I do have subtropical and tropical fruit (mangoes,sapodillas, dragonfruit, mombins, pineapples, citrus, sugar apple, soursop/guanabana etc) but I also would like to grow some nice veggies and such if possible, also some of those trees are you and will take a while to mature so I can enjoy veggies in the meantime.

Thank you for the securing suggestions. Someone from Arizona just advised me today not to wrap the foil around the rim as it might reflect sun back onto the plants and burn them, but I also read that the top parts of the plant can take hotter temps and sun as long as the roots stay cool. Also the mulch in the containers should cover the part of the foil folded over the rim. For some of my bigger ones I'll probably have to wrap and tape a second sheet to the lower half as I don't think my roll is long enough to wrap and cover the top and bottom with one sheet.

Here's a picture of where I usually have most of them on the lawn. You can see that it gets hard shade in the afternoon, but I guess even just the morning sun heats up the pots too much lol. Tropical lumen intensity problems.

Some of the trees are young*

Is there a reason you are growing them in pots? I can grow my bananas in the ground in S. Fl. If you have to grow in pots for some reason, can you did a hole and put the pots in the ground, that would keep the roots cooler. :o)

Wrap your forearm in foil and sit in the sun for a few minutes. I'm thinking that your wrapped arm will get a bit hotter than the unwrapped one. Again, this is just science, but I believe the same effect will take place when you wrap your pots with foil. Yes, they will reflect the sun's rays from the pots, but the foil will also heat and transfer that heat to the pots.

Fawn, I believe it has to do with the side of the foil. Aluminum itself is slow to heat, which is why they use it to make heatsinks for computers and such, but an object wrapped in foil with the shiny side out will have radiant heat reflected and away. If you wrap chicken breasts in foil and put them on the grill or in the oven, it takes a fair bit longer for them to reach safe temperatures. Though I am reading now that if you put the shiny side in, you can cook them faster... I may have been wrapping my food wrong. The thinness of the foil means that direct heat can pass right through the foil, this is why you still get grill marks if you cover grill mesh with foil before cooking burgers, but radiant heat, like the heat from the sun, gets reflected. This is also why people who do air-layering use foil, to keep the sun from steam-cooking the area they have wrapped in plastic.
As an aside, you can also boost the wifi signal in your home using foil. If your router is against an outer wall, you can put a foil wrapped board behind it to bounce the signal back into the house instead of letting it pass through the wall and to the outside. Unless, of course, you have a patio on the other side of that wall, then you probably do not want to reflect it.

I grow tons of plants in black nursery pots including David Austin roses and they all do fine as long as they get watered.

Michael - I've read a couple of articles that say that the side of the foil has nothing to do with it's ability to heat or protect from heat. Regardless, the reason we use aluminum foil for airlayers (I do dozens of them on my Crotons each year) is to raise the temperature underneath to stimulate root growth. So, I'm wondering if you have the science backward. As far as cooking goes, I've always used foil to keep moisture in for something that's being cooked in the oven. I've never foiled anything on the grill, so I can't speak to its use there.

I'm still of the opinion that foil will overheat a black nursery container and work against your efforts to grow better plants. All I can say is, try it and see what happens. If I'm wrong, I'll be the first to admit it.

From the Reynolds Wrap website:

Which side of Reynolds Wrap® Aluminum Foil should I use, the shiny or the dull side?
Actually, it makes no difference which side of the aluminum foil you use both sides do the same fine job of cooking, freezing and storing food. The difference in appearance between dull and shiny is due to the foil manufacturing process. In the final rolling step, two layers of foil are passed through the rolling mill at the same
time. The side coming in contact with the mill's highly polished steel rollers becomes shiny. The other side, not coming in contact with the heavy rollers, comes out with a dull or matte finish.