Freeze warning and row covers

I wasn’t really expecting the temps to drop until the weekend, but it’s now predicted to drop to 29 degrees tonight.  When we had snow a couple weeks ago, I covered my first planted potato bed with shredded leaves and draped an old insulated bedspread over that with good luck.  While I plan on covering the plants in my other two beds with the leaves since the plants in one are about 4” tall and just emerging in the other, the first bed poses a challenge as those plants are at least 12” tall now.  I did run across  a package of row covering I picked up a few years at a thrift store that measures 61” x 55’. I know I would have to layer it as 61” isn’t wide enough for my 4’ beds when you factor in the height of the potato plants.  My question is will the row cover offer any freeze protection?  I do have some PVC hoops left from my old greenhouse that fit the beds perfectly.  Would I be better to use the hoops and secure plastic sheeting over the top?  I know that potatoes will bounce back after the foliage has been nipped by cold but darn it, I don’t want to sacrifice that lush foliage!

I’m not a beginning gardener, but this is my first year of really pushing the seasons and I thought this would be the best place for this

just before sunset yesterday I found that beans, peas, squash, cucumber and radishes have just sprouted in the garden. carrots and second plantings have not come up yet. weather man said we might have frost or early morning freeze in next couple days. I don't have any good material to cover them with so I guess whatever does not survive ill just replant and set my first harvest back by about 10 days. don't want to count my chickens before they hatch so ill just keep planting stuff and do the best I can to give them the opportunity to produce a good crop. all my chestnut tree spring growth has already been froze off a couple weeks ag so I'm guessing they will be stunted this year, just hope the 4 year old and two year old trees survive. I'm thinking of contacting the chestnut expert at university of Tennessee Chattanooga for advice.

Michelle Heath wrote:  My question is will the row cover offer any freeze protection?

I've done low tunnel row covers before, and in my experience it offers just a little protection, like 2 or 3 degrees. I found that if temps started dropping into the 20's they would get nipped under the row cover.

Edit to add: I have also found that at at night before going to bed, putting things like gallon jugs full of hot water in the low tunnel seemed to radiate enough heat and would help prevent frosting/freezing and increase my chances for survival.

Bruce, I have lots of nursery containers that I've been using to cover individual plants. My grandma was a firm believer in using milk jugs with the bottoms cut off  to protect her tomato and pepper plants.

I finished up two more beds over the weekend and planned on planting beans until I heard the extended forecast.  

James Freyr wrote:

Michelle Heath wrote:  My question is will the row cover offer any freeze protection?

I've done low tunnel row covers before, and in my experience it offers just a little protection, like 2 or 3 degrees. I found that if temps started dropping into the 20's they would get nipped under the row cover.

Edit to add: I have also found that at at night before going to bed, putting things like gallon jugs full of hot water in the low tunnel seemed to radiate enough heat and would help prevent frosting/freezing and increase my chances for survival.

Thank you. I may combine the row cover with something else to increase the protection.  I have some empty milk jugs and 2-liter soda bottles that I could fill with hot water as well.  

ive been thinking about this all day and weatherman just said we will have freeze at night this weekend.your post has convinced me to try and prevent frost damage. ive got some grass clippings where I bush hogged a week or so ago and tomorrow will rake some up and cover up some of the cucumber, squash and beans that have sprouted. ive got something like probably at least 400' of plants that have just sprouted so far this spring and if I can save some of them it would be nice.

Times like this I can understand why putting things in neat orderly rows might be nice. I appreciate more of a wild look though, so I kind of randomly place a lot of things, but it's proving to be a pain to cover!

Bruce, I wish you luck!  I spent 2-3 hours yesterday covering beds and various plantings throughout the yard.  I'm happy to say that I only had one potato plant nipped and that was because the support I used for the plastic sheeting leaned forward during the night and the foliage came into contact with the plastic.

Tyler, I am appreciating the confines of the raised beds when it comes to frost protection but I also have plants placed in all parts of our yard and yes, it is a pain to cover.

I also had tomato and pepper plants come in for the night which isn't ideal but better than losing them.  Working on fixing the framework of the cheap 8-flat greenhouse and figuring out a better cover for my cold frame today.  Still probably won't chance tender plants in them but both are great for hardening off plants.

Another way to increase the effectiveness of any kind of fabric cover against freezing is to run a sprinkler over the top.  The water will freeze into the fabric and create a solid igloo of ice.  This is especially valuable if the freeze comes with wind, which makes the fabric vulnerable to blowing away.  In a light freeze, say into the 20's, you could shut the water off once a nice layer of ice is formed.  The heat coming up from the ground will keep the plants happy.  In a severe freeze just leave the sprinkler on till morning...you may have an inch or more of ice out there but the plants should be ok.  I have brought young tomatoes through 19 degrees this way.  Beware as it thaws out that once the arch structure breaks the chunks of ice may break the fabric down...I would pull any heavy ice to the side next day as it starts to melt.  Incidentally, running a light sprinkler directly on the uncovered plants all night will often save them, since water in the process of freezing gives off heat.  The biggest danger is the plants being broken down by the ice.  I've put sprinklers up on tall bamboo poles to protect an orchard of fruit trees this way.

well I did it, a couple hours ago it rained like crazy then got real cold, I went and gathered all the grass clippings that I piled up yesterday and got a bunch of burlap coffee sacks from the shed and covered up a bunch of the beans squash cucumbers radish and some of the peas that had sprouted in the past week. some covered with clippings and the squash and cucumbers that just had cotyledons, the first two leaves, covered with burlap.
guess I'll find out in next few days to week if it worked or not

yeah, if these sprouts survive I'll make special trip to ace hardware and get some dr earth homegrown veggie maker to give plants as reward for making it through this very rare may freeze

I wonder if smudge pots would be effective without doing the extra labor of covering. I don't know the science of it.

While the weather forecast for my area may have called for "patchy" frost, perhaps widespread would have been more accurate. Away from any frost pockets my garden is on a hilltop but it did not escape the bite of the cold air. Yesterday evening I gathered what I had on hand to cover the frost sensitive plants that I had planted earlier this season. Flower pots and five gallon buckets did the trick to cover my tomatoes, peppers and eggplants, and small clumps of hay covered the emerging squash and melon seeds I had sown, and herbs still in a cell tray were brought indoors. Sure enough there was frost on the ground, and dew that had settled into small drops on the overturned buckets had become frozen beads. I've never experienced a frost in May in middle or western Tennessee and the unpredictability of Nature brought a smile to my face this morning. I'm happy to say that all plants survived.

An update, observations and lessons learned.

First my first potato bed has come through practically unscathed. Since the plants were already about 12" tall, I opted to place 3 PVC hoops in the 4'x8' bed and spread a large scrap of clear polyethylene over the top.  It wasn't big enough to cover the ends and lacked about a foot of covering one side.  I covered that with two narrow black pieces of polyethylene, overlapping them at the top and holding it all in place with spring clamps.  I placed six gallon jugs of hot water through the bed before closing the plastic for the night.  I also used milk crates, flower pots, etc to cover any foliage on the sides that might come in contact with the plastic.  The hoops bent inward on the first night and I did have one of the volunteer plants on the end get nipped a bit.

My second bed did good for three nights.  The first I covered the approx 4" plants with dry leaves and covered with an old shower curtain.  We had a few good days, so I pulled back the leaves and let the plants enjoy the sunlight.  The second and third night we had rain and snow with a low down to 29F. Instead of covering the plants with soaking wet leaves, I opted to cover the plants with nursery pots and then cover with an old sheet and a plastic shower curtain on top of that.  The plants looked good the next morning.  Yesterday however, I was shocked to see that most of the plants in that bed had been nipped.  Although the weather was forecasted with a low of 31F, it actually dropped to 27F. Amazing that two degrees can make a drastic difference.  

The third potato bed also survived unscathed. The plants in it were just breaking through the surface of the leaf mulch and I added a few more inches of mulch to the bed before the cold weather set in.

So, what did I learn from all this?  First, never ever trust the weather forecast when it comes to freezing temperatures. I will always err on the edge of caution from this point forward.  Second, though I did provide framework for my onion, cabbage and beet bed and covered it with an old sheet, it likely wasn't needed.  I need to store some of my leaf mulch in a covered container/location in the event I will need to use it as a frost covering in the future.  I did manage to dig through the pile and find dry leaves in the middle, but most were soaked.  Some additional experimentation is needed concerning the jugs of hot water.  Is there a temperature increase or does the water radiate just enough heat to protect the surrounding plants?

An additional observation is that asparagus is susceptible to frost damage as well. After a hard freeze I was successful with pouring cold water over the plants shortly after daybreak. Unfortunately the last night, ice formed on the spears and most of the taller ones were damaged.  I'm planning to grow asparagus as a market crop in the future so will need to allow for some sort of freeze protection in the future.  My rhubarb however wasn't damaged though I covered about half of my plants.

Future plans include purchasing some lengths of rebar to secure the PVC hoops and getting the garden area fenced.  I haven't yet mulched my paths and they are currently a muddy mess from all the trampling I've done around the beds in the last week.  Of course the paths aren't mulched because we have cats who will use the paths as a litter box unless the area is fenced off.  The beds all have temporary fencing/barriers to keep the cats out, but deer will soon be my next worry.