17 degrees? coping with spring frost in a garden

IAM NOT EVEN SURE WHAT TO SAY ABOUT THIS: Weather that in less than a week goes from near 80 to more like 18 (other estimates say 17, even, for tonight, with winds up to 40 miles per hour as the icing on the ice-cream cake). In March. A March that looks more like late April, or maybe May. I dared last week to pot up giant bowls of pansies and violas, all of which are now taking shelter under upturned wheelbarrows and garden carts, like the one above. What else is there to do about a hard freeze that’s threatening a big swath of the northern and eastern section of the nation?

Watering the soil in pots–or beds–well before tucking things in is the first line of defense here, and what I did this afternoon. Cornell says that moist soil can hold four times more heat than dry, and also conducts the warmth toward the surface faster to aid in frost prevention.

Watering the actual plants–such as with a sprinkler or hose-end wand–to wash off the frost just before dawn (the coldest part of the night)–can help when temperatures will be just around freezing, but with 17F forecast, I’m not setting any wakeup alarms here. Useless.

I’d rather turn large containers and boxes (or my carts) upside-down over things than lay material right on top of succulent, tender plants–especially when high winds are forecast that will whip the material around. When I do need to resort to a fabric covering, like the side-by-side whiskey barrels of pansies above, I avoid stiff plastic or paper in favor of cloth (such as the a frost blanket made of Agribon 50).

Either way, I weigh down my protectors–even my wheelbarrow, on a night like tonight is meant to be has a rock on top of it (top photo). Pillow cases can come in handy, since you can slip them over certain things. Whatever covering you use–and it’s better if it doesn’t weigh on the plants themselves, of course–it must go on before the deep cold begins, and must come off before the sun warms things up the following day. In my case, with 20s forecast Tuesday night as well, I’ll be recovering things tomorrow.

The scariest part is loss of tree buds on one-chance-per-year fruit-producing crops like stone and pome fruits, some of which are showing color nearby (and others are already open because of last week’s record warmth). The University of Illinois Extension says a fully open apple blossom, for instance, can withstand temperatures of about 28 degrees F, with substantial injury at 25 degrees and lower.

Pray for clouds tonight, which help keep warmth from the earth down nearer to its surface than a clear sky!

more on frost

March 26, 2012


  1. Suzy says

    I live in SE Wisconsin and this year has been bizarre as far as temperatures go. We have already had numerous day in the high 70′s and low 80′s. Needless to say, many of our perennials are growing rapidly. Tonight it is supposed to get down to 28 degrees. We have A LOT of sedum plants and Hostas on our property. Do I need to cover these to protect them from the freeze? Most of the sedum are fairly large already. But they make up the majority of our landscaping and I don’t want to lose them.

    • says

      Hi, Suzy.The Sedums here are showing but are like knobby clumps — not all standing up with their stems extended yet, but still down near the ground. They have been through two hard freezes like that. With the Hostas, I don’t worry so much if they are merely pointed, tight shoots poking through the soil, but if the shoot have started to unfurl: trouble.

  2. Laurie says

    I too gave into the pansies and tulips blooming at the garden center. They are currently beautifying the garage.

  3. Sheryl says

    I have seven blueberry bushes that are all in bloom. The weather forcast is for snow tonight and tomorrow with lows around 32. I don’t know what to do with a snow forcast! I have been covering my bushes with sheets, and that has worked out well. Will that protect them if it does snow? They are saying 6 inches of snow. What a disaster!!!!

  4. meri says

    My absolute favorite thing to cover plants with are crib sheets – the elastic casing keeps them in place and they are just the right size for most perennials and great for hostas. I buy them up at Goodwill. I’ve done the 5 hour water/cover everything routine twice in the past two weeks here in Asheville,NC. Everything survived the freezes only to be utterly destroyed (on a gorgeous day) by a freak 2 minute hailstorm …

  5. says

    Yes, I’m very worried about both my lilacs and my apple trees. The lilacs I might be able to cover, but the apple trees – ugh. Hopefully it won’t dip past 30 here in Virginia tonight.

  6. Judy Walther says

    This seems to be the winter that won’t quit…here in Atlanta today 4/15 is the average last frost date and most years we’re in high gear by now and in fact I did plant a couple of tomatoes on Sunday…it was 80 degrees!Today I covered a lot of stuff up(Meyer lemon in a pot,blooming miniature blueberry,white ginger, just peeking out,agapanthus in a pot and of course the tomatos and hauled other things in the garage that I hadn’t planted yet. We had tons of rain last night(needless to say I didn’t see the Blood Moon last night) and the prediction is for high 20′s in the Northern suburbs where I am and the wind is blowing like crazy. I use heavy black plastic ,large buckets,12 inch clay pots,plastic tubs…whatever works!

  7. Brigitte says

    I won’t be able to help the pansies, b/c I’m not home, but hopefully they will be OK.

    I usually plant my tomatoes in the ground at the end of April b/c I’m on the CT shoreline, but 2 years ago, I got a frost. I was traveling for business, and called & begged my neighbor to place plastic grocery bags over each 6″ plant. But it didn’t work. I read later to cover, but plastic doesn’t work.

  8. Jan scarlett says

    i planted a whole new bed of annuals then saw the weather and dug them all back up,repotted and put them back in the garage for the next 2 nights. Only a real gardener would understand….

    • margaret says

      Hi, Jan. I just didn’t have the stamina. (I think this recent winter has just taken its toll!) I will have to replace the pansies I suspect.

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