Winter Temps & Newly Planted Plants- Need Advice

Having lived in zone 8B in SC for 8 years now, I can' recall temps reaching the 40's, 30's or even lower in November...until this week. Daytime temps have been in the 60s and 70s and our low temps have been a few degrees below normal for this time of year. Lately, nightly lows have been somewhere between 40 and 60 degrees.

I understand frost and freeze, although we have barely seen either since Jan or Feb of 2010. So usually I really don't have to worry about protecting plants until mid January through mid-March.

Today's daytime temperature is supposed to reach 70 and the nightly low is predicted to be 37 degrees. Wednesday we're expecting a high temp of 53 and a low of 35 over night. Aside from tonight and tomorrow, the forecast for the next 10 days pretty much has the highs in the low 70s and lows in the mid-50s or lower 60's, with 2 nights possibly reaching the lower 40's.

But I am a little confused and need some advice. From midnight to about 4am, the temp will be in the low 40's, and from 5am to 9am the temp drops into the high 30's. I know 37 degrees isn't "freezing" but we are expecting wind speeds around 20mph during our low temps and it is supposed to be 37 degrees but "feel like 28." Tomorrow's low is 35 but "feels like 30."

I am guessing it is safe (or wise) to assume that even though the actual temps are not below 32, the "feels like" is below 32, and most likely turn herbaceous perennials, and non-hardy plants, into mush. I planted some things a month ago when the highs were in the 80s and lows in the 60s or 70s. I fear that they probably have not established a good enough root system to withstand a "feels like 28."

So, should I dig them up and put them in pots and just overwinter them inside, then replant in spring? Or dig them up, pot them up, and replant in 3 or 4 days when the lows are in the mid 50s? OR should I just cover up the plants with pot or something because they are still small enough to cover up with a 12 inch pot. The plants in question are Alternanthera "Little Ruby", Colocasia "Coffee Cups", and some Autumn ferns (which are only about 6 inches tall and wide.)

Any advice is appreciated.

Covering the plants should protect them, but if you put some straw or leaves around them and then covered them up you would have more protection.

I can do that, ford.

One more question....I remember reading something awhile back about watering plants before a frost or freeze. Do you think I should water the plants before covering them?

You're not going to cover them and never UNcover them, right? Watering should help stuff survive a freeze, although it's more useful for a really deep freeze like they have up north. If you want to water them, then cover them, that couldn't hurt.

As long as these are plants that are expected to overwinter in your zone, and you let them have 4-6 weeks to establish their roots, you should be fine.
http://davesgarden.com/guides/articles/view/1474/

Yes, I plan to uncover them as soon as the freeze warning is over in my area. Like I mentioned in my first post, the daytime temps are supposed to be going back up to the 70's and nighttime temps into the 50's and 60's after Thursday morning at 9am.

This morning it is 35 degrees and "feels like" 24 degrees. I think the wind is what is so harsh right now ranging from 13mph to 25mph with gusts up to 35mph. It looks to continue this way until tomorrow morning.

I checked on the gardens through the window (too cold to venture outside just yet LOL) and my Alocasia and Colocasia are all surprisingly still standing strong and sturdy. Even more surprising is my coleus is just fine, too. I took cuttings yesterday just in case, though. But according to several weather websites, the real test begins tonight at 8pm and will continue through 9am tomorrow, with a possible freeze lasting 6 to 8 hours.

Our average high for this time of year is 71 and average low is 51, so this cold is out of the norm. I'm probably fretting about it more than my plants are LOL

carrie, the Autumn ferns have been in the ground for about a month and have put on new growth since then. The Colocasia Coffee Cups were offsets of a mother plant that I planted about a month ago, but they are still very small (under 6 inches) so I potted up one of them and brought it inside, and the other I covered with a pot. The Alternanthera Little Ruby was planted a week before Halloween. 3 of the 5 were doing good, but the other 2 were dropping leaves the last week or so. However, I think it was because I might not have kept the soil moist enough for them to start establishing a good root system. I covered those 2 up with pots. I will check on them later today and if they look worse, I will just pot them up and bring them inside, and replant them in spring. I did take cuttings from them when I first planted them because some stems were sticking out much farther than the rest. They are rooting good in a vase of water on my kitchen window sill. So at least I have some back ups :)

The feels like temperature really doesn't have much direct meaning to a plant. You are talking about windchill and that mostly applies to something that is warm like a human or animal. Windchill takes the cooling effect of wind on something warm and translates it into a temperature.

When you see conditions given as - a temperature of 35°F with a 20 mph with a wind chill(or feels like) 24, it's just the same information given in a different format. It means that you'll lose heat from you body at the same rate in those conditions as you would in 24°F and calm. It doesn't mean, that if you set a bottle of water outside, it will cool to 24°F.


When I wrote that windchill had no direct meaning to a plant I meant temperature wise. Since wind speed is part of the calculation, what ever drying the wind does will affect the plant.



Covering you plants to protect them from freezing will work provided it doesn't drop into the lower 20's. There are several things that need to be done. Make sure that the wind can't blow you cover loose. Any air leak will cause the protection to not work. Be sure the cover doesn't touch the plant. This is particularly important using things like sheets, tarps and plastic. Any leaf that touches the cover will freeze.

In addition to tarps, old sheets, plastic and other things like that, boxes work well. I've used five gallon and smaller pails, garbage cans, milk jugs with the bottom cut out, leave the cap on. I like your pot idea, but I'd tape over the drain hole.

My personal recommendation, which I've never seen written any where is to start early. I'll cover a plant at 2pm. Here's my reasoning. The plant isn't going to miss a few hours of sunlight for a day or two. If you start from a higher temperature to slow the cooling, the plant should stay warmer longer. If the sun is out you may get a little solar gain. I'd rather be going into sundown at 45°F instead of 35°F. It's a lot easier to cover things when it is still light and you can see what you are doing. Additionally the more comfortable you are, the more likely you are to do it right. If you are out there in the dark freezing yourself it becomes a lot easier to say "that's good enough."

This message was edited Nov 13, 2013 9:24 AM

Yeah Doug, I was thinking about that but you said it perfectly.

Doug, you've given me some new ideas for covering potted plants. Thanks. And for the very first time, I started preparing for a freeze in the afternoon. Yea, me!

I think it's always a good idea to water plants before a freeze. I think it's supposed to keep the ground (or pots) temp a degree or two higher. Or not. Know I heard something like that sometime somewhere.

I think the idea behind watering plants before a freeze is that it gives the pot a lot more thermal mass and thus it cools slower. It also may be a misunderstanding coming from what they do in vineyards to keep grape blossoms from freezing and thus save the grape crop. The irrigation sprayers are run to keep the flowers wet and keep them from freezing. All that fine mist also keeps the air a little bit warmer.

I could be totally wrong BUT, I CAN'T see a problem with any of the temps your talking about, nature actually knows better than us and most plants can tolerate a couple of days frost / freeze BUT not underground freeze, that kind of ground freeze would then freeze the roots,

The best way to help prevent the foliage of a plant being burnt by frost, wind or even very hot sun is to throw a covering of horticultural white fleece over the plants and hold in place by a few stones, once the frost / freeze or icey winds have past, remove the fleece and keep handy for re-applying if the same conditions are reported to return.
I would be very worried about putting pots over plants that are still growing, the pots deprive the plants of light and this can cause the plants to die back, best place fleece, clear plastic little tents made with garden canes or even those plastic containers you buy Tomato's / strawberries in at the stores, these are cheap and easy to handle covers for temp covers / protection, better than the severe steps your previously thinking about and totally confusing your plants, they are young and strong enough to recover a few colds nights.
Best of luck and kindest regards.
WeeNel.

Doug wrote: If you are out there in the dark freezing yourself it becomes a lot easier to say "that's good enough."
---

I literally laughed out loud when I read that.That statement is oh so true.Yesterday, I started early prepping plants for the predicted overnight freeze and was running here and there in a very determined, yet somewhat frantic manner. Today I stepped outside to retrieve a very wilted, and forgotten, potted Vinca and brought it inside. On the way back in, I realized I didn't cover one of my favorite New Guinea Impatiens. I stopped momentarily and quickly scanned the yard for a bucket or what not to cover it up with. Then the chilly 20mph wind slapped me in the face and I ran inside telling myself, "It'll be ok one more night."

Other than the shriveling Vinca, everything else looks ok so far. I did notice that some of the leaves were torn and stems bent on my Colocasia Fontanessi and Diamond Head, but that's ok. I expected that to happen. It was due more to the gusty winds rather than the cold temps

Doug, thank you for explaining the whole wind chill thing. You told it in a way I could actually understand it. In fact, everything you said made a lot of sense. I appreciate your input.

WeeNel, I don't have any horticultural white fleece or I would have used them. Where I live, we normally don't get temps this cold...especially in November. Last fall and winter our highs stayed between 50 and 79 degrees and we had 2 or 3 lows in the 30s during the month of March. I probably should invest in some fleece just in case we get sudden unexpected freezing temps again.

Glad you and most of your plants survived!

Just for clarification, any of the things that are mentioned above are to get plants through a few hours of freezing temperatures. Most of those hours are in the dark anyway and the plants aren't getting any sun anyway.

I made the assumption that everyone understood that the various covers are removed once the sun comes up and the temperature rises above freezing.

What happens in much of the US east of the Rocky mountains is that the jet stream dips south, and pulls arctic air south with it. It only affects the southern part of the country for a couple of days. If you can keep your plants from getting killed during those couple of days, you'll have another month of gardening left.

Two years ago we had a very warm spring and then a cold snap. The result was that many perrienials started to grow too early, frost then hit them and damaged blossoms. Fruit crops were non existent in some areas.

I had rhubarb growing and while a freeze wasn't going to kill the plant it would have set it back. I covered it with a mix of hay bales and foam insulation held down with concrete blocks. It worked.


This message was edited Nov 15, 2013 8:35 AM

You are right about that Doug. We used to cover with pots and cardboard boxes for small individual plants in early spring - just for the night. Larger plants such as azaleas about to bloom required quilts, towels, sheets or even plastic sheeting (this had its own issues though).

Hi Doug, glad you clarified the pot covers were removed after daylight, I mentioned it purely because the thread is so interesting and felt maybe new gardeners would be following it and not understood the pots or dark coverings were very temp.
You can buy the fleece at garden store by the packet (different sizes) or by the metre, the metre is cheaper but either way, it costs pennies, can be washed in delicate wash cycle in laundry machine. I've on occasions ran stitching Machine or by hand and made into bags to suit the size of plants to be covered and gather this bag around the base of plant and tie it off with soft garden twine, it's easy to remove, stick the twine inside the empty bag and it's ready for next frost warning and no looking for all the stones or weights to hold the fleece in place IF you are only covering a few pots, a border requires a length of fleece and needs weighed down to keep in place if windy.
This works for me but I guess it all depends on wind, how many pots you have and the time you can spend out there in the freezing cold LOL.
Good luck and best Regards.
WeeNel.

Here in South Carolina, the rare times we get freeze or frost warnings, it is usually for no more than 6-8 hours, and like Doug said, it is almost always during the night. Once the frost/freeze warning is over, I usually wait another hour or two before I uncover my plants so the temp can rise a few degrees. Of course, if the warning expires at 2am, I don't uncover them until I wake up and have coffee LOL

SavvyDaze, love your style, especially prioritising the morning routine of the coffee intake before you decide what order to do any other chores LOL. My kind of lifestyle.
WeeNel.