I'm planning of using perennials in some of my containers this spring/summer. I will only use plants which are hardy in my zone. Does anyone overwinter their perennials in containers? I haven't tried this before except for hostas which always come back. Any advice or web information would be appreciated.
Thanks,
Molly
Question re: overwintering perennials in containers
Molly,
I've heard here - and elsewhere - that you can plant perennials in containers and overwinter them, but that you should give your plants a zone or two extra clearance. I have been growing a delphinium for years in a pot on the patio (not very well, as I've learned here) and have enjoyed that immensely. This spring I'm planning to plant a few container combinations of perennials; one with dahlias and other tender perennials (to take inside in the winter), and one with sturdier very hardy perennials. (I can't decide if I should grow shade lovers under a tree or sun-lovers and follow the sun around!)
xxxxxxx, Carrie
Check this thread out. I think this is the one where all the plants are over wintered in a basement.
http://davesgarden.com/forums/t/563917/
LOL! I've been following that thread! Those plants are for the most part non-hardy perennials, or one of those other terms that sounds unlikely. In other words, they would die off each winter if she left them outside.
xxxxxxxx, Carrie
Been doing it for 5 years right across the River from you.
I started when I joined a Balcony gardening group.
The trick is not to let the Containers keep thawing and freezing.
I'm doing Zone hardy plants for this zone and pushing Zone 7.
I'll post later on my technique or see if I can find a link to where I answered this question before.
Ric
By over-wintering containers in an attached, unheated garage, I'm able to keep plants hardy to 2 full zones higher than where I live. Plants left above ground w/o protection should be hardy to at least 1 zone lower than yours.
Freeze/thaw cycles have almost no effect on o/a plant hardiness unless soil temps go above about 45* F. for several days & the plant is stimulated to growth. Containerized plants tolerate frequent freeze/thaws with no ill effect. Problems arise when temperatures drop below those which plants are genetically prepared to tolerate. These low temps kill root tissues first & often the demise of the entire plant follows. Even in plants growing in the ground, the primary effect of freeze/thaw cycles is heaving and subsequent dessication of root tissues, though exposure to low temps can also take a toll.
Al
How cold does it get in your unheated garage? I have to admit that it must provide some protection. I was surprised one morning when I took off for work that a bottle of water that I had left in the car wasn't frozen and it was below freezing outdoors. Then again, one morning I did have a bottle of frozen water in the car. In my zone, I don't think it would be safe to overwinter a container in an unheated garage.
In our area here it is not uncommon for the temps to go from below freezing days and teen/single digit nights to a week of more w/ temps in the 60's and above freezing at night.
Setting off the growth spurtswhich get zapped w/ the next Clipper.
If you can keep them dormant thru this by not allowing the soil to thaw you alleviate the problem.
In late Fall I stack the pots in a N/E corner.
More tender pots to the wall and on the ground, hardier pots to the outside and top.
Then wait until a below freezing cycle occures.
I then cover the pots w/ packing blankets.
Usually 2 layers thick.
If we are getting a sub-zero blast and there isn't a snow cover I may throw more on.
As no Sun hits this area it never heats up above freezing but never gets below 25 or so in there.
Basically they are in a warm freezer :-).
In Late Feb/ Early March I begin peeling the blankets off.
Any pots showing growth I bring out from under the blankets.
These are almost always the hardiest plants.
By April the blankets are off and the plants are allowed to emerge normally.
I do 40-50 pots from Zone 6-7a this way every year and rarely lose a pot.
Ric
Ric
Beaker - air temps sometimes get as low as 25* at eye level. However, soil in containers that are on floor never freeze because of moderating effect of earth's heat radiating through floor. The hardier plants are set on temporary tables made with plywood & sawhorses.
Remember too, frozen soil does not = a frozen plant. Temperatures that drop low enough to freeze soil water solid are not what actually kills tissue. Even when temperatures drop low enough to freeze inter-cellular (water that is between cells in tissues) water solid, it doesn't kill plants hardy to your zone. However, when temperatures do drop low enough to freeze intra-cellular water (the water bound within cell walls), this freezing destroys cells and kills tissue, causing the death of affected plant organs.
Al
NOW is when I need to know this! It was fun to dream about in March, but now I have a l-a-r-g-e shipment of flowering perennial plants on my patio. A lot of them are different sizes than I expected, not to mention the bed I was planning for them isn't finished yet. Some of them seem like they'd do well together in a container... should I do it? Or should I just pot them up and line them up where they were supposed to go? A little hint for the maker of new beds, i.e. DH. They're mostly front of the border/ground cover types, and the wall/edge around the bed isn't really there....
xxxxx, Carrie
I'm glad this was bumped up again. So are you all saying I can overwinter, say an alstroemeria which is zone 5 in my unheated zone 4 garage? That all I need to do is wrap it in some packing blankets? BTW, where do you buy packing blankets?
beaker_ch, you MAY be able to winter it in an unheated garage.
Too many factors go into it to say you certainly can.
Is the garage insulated? Get a lot of sun? Free of drafts?
If the answer's no then it many well be just as cold inside the garage or colder than outside.
The Zone rating is an average temp also.
Have a bad winter and all bets are off even if your garage answers were yes.
We/ve had a mild winter, temp-wise the last two years.
We didn't even hit single digits.
You should though gain a zone in the garage.
Packing blankets are available at any moving and storage company.
Carrie,
If you're doing the containers for the short term (over the Summer) combos are fine.
You will need some pretty big pots though to give plenty of root room..
If you're going to leave them over the winter I'd go w/ one plant type /pot.
Then you can just arrange them on the patio as if they are in the beds.
You can always fill in w/ annuals.
Ric