The only plants I have that are not hardy to my area's all time record low of 20F are 2 coconut palms. I typically cover them right around dusk, but there are times where I've seen a weather forecast for a moderately cold temperature early in the day (40F-45F) only to see the forecast change along with a thermometer reading in the 30s by bedtime. Then it's a sprint to get the extra comforters.

As far as timing goes, I'm not sure that it matters that much. Could it trap more or less heat? Yes, and I'm sure that if the cover is placed when the sun is shining, then the temperature could get quite warm. I wouldn't want to encourage active growth during a freeze event, though.

One exception to this rule would be if you wanted to cover the ground with a box and some extra layers to keep the soil temperature warm enough to discourage root rot, or if the temperature is going so low that you're going to need every single degree you can get. At that point, you're probably better off with lights under the cover, or not planting plants that are that tender in the first place.

In my experience, plants tend to perform better if the temperature range is more stable, where they will stay dormant, but not freeze. I'm interested to hear other opinions on this topic as well.

I cover mine at dusk, take the cover off as early as possible. No plastic.

Orchids come inside anywhere below 50, tropicals below 40, special plants that can't stand freezing come in at 35 or below, and outdoor plants get covered when 35 or lower is predicted. Tonight, I'm PRAYING that we don't actually get down to 28. I don't think we will, but it's already down to 42, and clear skies, which isn't good. I only covered a few things, and I'll uncover them as soon as I get up and about. Everything else will have to take its chances.

What I hate is that I can't bring in my tomato plant, because it has green tomatoes on it that I was praying would ripen before this cold weather hit.

Hi

About the only thing I regularly cover is the Vandas that are attached to a palm. I use a tepee covered with frost cloth if in the 30's I add a heat source with a thermostat as I keep them above 50

I find the frost cloth far better as protection as I can leave it in place for the usual 3 day duration of the cold. without the problem of overheating when the sun comes up. I remember once covering my shadehouse with clear plastic and it sailed through the 28 degree night with an electric heater. Morning temp outdoor 30 indoor 55 feeling smug I went to work, when I came home outdoor temp 65 indoor 151!! Needless to say I lost everything to my "protection" lol.

They make the frostcloth in several grades including a type the produces heat via a chemical reaction but have never tried it. I use the medium weight being sure not to allow leaves to touch it. which is where the" Tepee" comes in. Easy to disassemble and store . has never overheated

The present front looks like 50's for the low so no problem

I maintain a "warm "room" for my tropical fish so really sensitive plants spend the entire winter in there as I quit maintaining my shadehouse .

I'll bet my tomato, roses ,primroses ,treeferns hydrangea will love the break form the heat??lol Goodluck!! gary

I don't have many tropical storm only a bat plant, bird of paradise, Duranta, chenille and ficus Benjamina. I go by the "better safe than sorry" school of thought so the first 4 go in the small greenhouse we built for that purpose when temps go below 50 at night. The ficus when it gets below 40. And 3-4 more when it will freeze.

Last year we had 2 nights of 27 and my very large, unmovable pot of impatients was in full bloom. So I put a light layer of straw over the plant then covered it with a tarp that reached to the ground and pegged the tarp with rocks. I did this around 5pm thinking the heat should be trapped under the tarp and save the plant. Temp stayed at around 50 the next day and since the plant is in the shade I didn't t uncover it until the second day when we were done with that *#%* cold. It worked!

As a general rule, I don't (won't) plant things that need too much care, but as an MG mentioned once, "We gardeners tend to kill more plants than we save because we keep trying to push the boundaries." My Tropicals bed is the only place I push the boundaries and even then they are mostly the more cold-tolerant varieties of Tropicals. Last year I brought a number of plants indoors and my daughter's cat went ballistic with all the new toys and chew things (none made her sick). So I am trying not to do that this year or ever again while there is a cat in the house. Besides, my most 'precious' tropicals are just too big to dig up and bring in.

Right now, even after last night's freeze, I have two bananas (unkown variety, some suggested they might be a type of Cavendish) that will likely flower and fruit this coming growing season and I am doing all I can to make sure they make it through unscathed. I wrapped them in lights, tented the entire bed and laid down a layer of still-decomposing compost as mulch (around the bed, but not near any woody plants or the bananas). Today I put a spare aquarium heater into the small pool in this bed thinking that a 60-70°F pool of water will help with the microclimate.

Everything else in my yard is on its own and anything that doesn't make it will get replaced with something hardier. Looking around today and taking note of what took frost damage, I feel fairly certain everything touched so far will come back. I was surprised my unprotected Monstera deliciosa made it through looking okay. Well, unprotected by me, but protected by the trunk and canopy of an oak.

Since starting this thread, I have taken to starting to put up the tent around 3-3:30, which is when the thermometer starts dropping in temp. The bed falls into shade around 4:15 and if the day is sunny, I will leave the last panel off long enough for the last few rays of direct sunlight to sneak in before sealing it up. So far just the tent is enough to allow that bed to lag behind by 1 or 2 degrees compared to surrounding temps, but it eventually reaches the same low. With the lights on, it maintains a temp 5 degrees warmer than outside. Not a whole lot of difference, but this morning it was a difference of freezing and not freezing. And that made it worth it. I won't need the lights again for a few nights, but I am interested to see what difference the aquarium heater will make.