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Overwintering Plants in the Nursery.
Just curious on how other growers overwinter their plants. We live in a very challenging climate. Almost 5000 feet elevation annual precip is around 12-15 inches. Our winters can be snowy or lately not so much. Not uncommon to see temperatures of -20 without snow cover. We have already had -12 this month.
So what do we do to protect our perennials, shrubs and trees to make sure they get through to the next growing season?
Last winter we left almost all of our gallon pots out and figured they would be just fine under a snow bank on the North side of a 6 ft fence. We lost almost all of them (98%). It was a very costly mistake that I wouldn't like to repeat.
So what do we do to protect our perennials, shrubs and trees to make sure they get through to the next growing season?
Last winter we left almost all of our gallon pots out and figured they would be just fine under a snow bank on the North side of a 6 ft fence. We lost almost all of them (98%). It was a very costly mistake that I wouldn't like to repeat.
Replies to This Discussion
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Permalink Reply by Steve on -
If your winters are that severe I would suggest several things. First Use a strong Hoop House! We use Jaderloon Hoop houses and we have had 3 ft of wet snow on them with no supports down the middle of the hoop house (unheated) and no problems! Second because it gets so cold I would suggest putting the large diameter EDPM tubing in the floor gravel and heating your houses with hot water from an outdoor woodstove such as the ones manufactured by Heatmor. You only need to keep the temperature at 36 degrees F. We like to use removable dutch doors on our hoop houses. They are 2 seperate removalbe doors stacked on top of each other. At each end of the hoop house. Any time the temperature is 40 or above the top doors are removed. If the temperature reaches 50 the bottom doors are removed. I'll post pictures tommorrow.
Hope this helps
s.
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Permalink Reply by Jessica Lenker on -
Here in central PA, we are not that cold, but we do get harsh winters. We have not been above freezing in quite a while and night temps are single digits and teens. We house all our perennials in double poly hoop houses with minimal heat, set for 28-32 degrees F. The flooring is just black landscapers fabric. It seems to accumulate some heat on the days we actually get some sun and that helps with the first few hours after the sun goes down. I've also noticed this year we've had enough snow to build up two feet deep between each house adding a bit of extra insulation. We may have to incorporate a man made between house insulator next year.
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Permalink Reply by Eric Larusson on -
In Truckee we have had -25°F so far this winter with little snow. We have had pretty good success with woody plants #1 and up in shade - we simply put up pallets on the south side of small blocks. Then spray with Ropel and Plantskydd - lots of snow is better insulation and worse vole damage. For the perennials we've gone to keeping them in our Poly-tex retail house - it's like a cold frame that moderates temperatures ...slightly, slowing the rates of freezing and thawing. We get LOADS of snow and have to blow away from the sides of the house - we remove the purlins inside so the snow can slide off as well. In the mid-west I've seen growers spread 8" or so of loose straw over the #1 perennials in late fall. Ice lenses in pots kills many each winter.
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Permalink Reply by Lamoureux Greenhouses on
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this is what we do in the northeast we also get -20 temps.we put them in a double poly house with white poly on top with no heat. we sometime loose a few but 90% make it. good luck its not easy being green.
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Permalink Reply by Shannon Theall on
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How often do you water the pots? What do you do with the trees and shrubs? Some of the trees are to large for the greenhouses. Do you do pot in pot in the ground?
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shanon all perennials shrubs we even stack things in crates and lay some of the trees down the taller trees we mulch in outside. we water about 4 times during dec to march. just water thim good when you put thim away.the only trees we winter over are jap maples. good luck dick l.
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Permalink Reply by robin elstermeier on
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we take both our plants that we over winter pack them as tight as possible and cover them with
3 to 4 inches of loose leaves then water them down in an open winter we water them another
time in december and january about 5 to 10% loss in maximum
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Permalink Reply by Jeff Merritt on
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Here in the midwest - Illinois we do occasionly have some very cold temperatures. It has got down to -15
this winter but that is usually the extreme. We over winter our perennials in hoop houses. We pack them in tightly in rows and make sure they are watered well before putting them away in the winter. You do not want them too wet or too dry going into the winter. We then cover them with poly foam insulation which is about 1/4" thick, this can help add about 30 degrees when it gets real cold out. We usually have good results with this method as long the plants do not get too wet when things start warming up and snow along the edges of the houses starts melting. A good layer of pea gravel under the plants will help moisture from collecting under the pots. You also need to put mouse poison in the houses to keep rodent damage to a minimum. Container shrubs and evergreens also overwinter well in hoop houses as long as they do not dry out too much over the winter. Container trees do well when mulched in with bark
covering the containers completely and making sure bark is pushed down between the voids when lining up the trees when you mulch them in. With container trees due to the larger containers, we never seem to have an issue of them getting too wet or too dry over the course of the winter. I have experimented with smaller shrubs and perennials left out side and they never seem to fare well unless mulched in well and covered with some kind of poly cover. If you have more touchy plants such as Rhododendron, Holly,
etc. you almost need a house that has supplemental heat that does not allow them to freeze completely. Hope this information might help.
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Permalink Reply by K Eller on
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It's gonna be work, but if you trench in the pots and then cover with winter blanket, a layer of straw and then winter blanket. It's worked for us.
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Permalink Reply by Mary Lou Hoskins on
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Here in Maine we are real cheapskates. Instead of a hoop house we store our perennials under our "benches" (pallets on cinderblocks) and cover the whole works with a material known as "winter blanket" (a heavy white felt) and a layer of plastic to keep the water out. We usually use old greenhouse plastic. We put lots of mouse bate underneath too to keep the mouse damage to a minimum. This works very well although there are always some varieties of perennials that hate being in a pot for the Winter and just don't survive well. Trial and error has taught me to store those few things in my root cellar. The shrubs and trees we just lay down on the ground and cover the same way, also remembering to bait for mice. It isn't the freezing that kills things, it's the freeze-thaw cycling that does it.
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Permalink Reply by Maggie Sauvain on
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I am in zone 4 in New Hampshire. We cover the nursery , after cutting everything back to pot tops, with one layer of blue tarping and secure it around the edges with boards and cinder blocks. We also put out rodent bait under the tarps. That's for the perennials. For my shrubs we have a few hoop houses with clear plastic and some air circulation at the ends. My potted conifers (2-6ft) are on ground cloth and fairly close together and are a bit sheltered by some tall trees. Otherwise, no cover needed. I've had real good luck with this system so far. I don't tarp till we've had a few mid to low teen nights. I don't leave the tarps on any longer that i have to in spring either. A key to making all this work is your soil. We use a mix with a lot of bark and sand which drains well. It is freezing and then thawing then freezing that is the worst scenario. I figure we get most everything through the winter this way. you sound like a bit more severe conditions , but we do get some long stretches of below zero sometimes with no ill effects. Good luck.
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Permalink Reply by Carl on
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Here in southern Michigan we overwinter everything in coldframes if at all possible. At times we will double cover plants inside the houses for added protection during really cold snaps. It will get down to -10 for a few nights every winter and the winds seems to always blow. We always use opaque (white) 4mill plastic and can get two winters out of it. White plastic moderates temperature swings. The rule of thumb I have been told is "each layer of plastic equals one growing zone" ie. 5 = 6 with one layer of plastic. Depending on the winter we will water once. We wait to cover just before Thanksgiving. Covers come off late March early April depending on the spring.
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