not.available writes:
I have heard hot caps for tomatoes are very useful. I am a bit confused
though, do I leave them an all of the time? Just at night? Please advise.

When I was a child growing up in eastern Washington, hot caps were quite
common. Because there were fields full of them, I seriously doubt they
were removed and replaced. They were most likely left on until the plant
"outgrew" them; I don't recall ever seeing anyone remove them.

It will be interesting what others have to say.

In past years, for early planted tomatoes in my garden I've placed large
plastic bags (heavy weight purchased at a commercial cleaning supply
store) over the tomato cages at night and removed them during the day,
replacing them late afternoon for that evening. This year, because there
was space below the cage under the plastic bag (cage taller than the bag)
in past years, I chose to cut the end out of the bags and placed them over
the cages so they actually touch the ground, held in place with
clothespins. It's really difficult to know how this year worked compared
with past years since I planted later this year. Ideally, the bag would
have touched the ground enough to be secure while still in tact for a
"roof" over the plant to help hold in heat. I suspect the grass mulch
around the plants has done more than the plastic bags, either year.

Glenna