Not sure about the hardiness... the plant survived that many winters either in the ground or in the pot you see there. It did not thrive but it did not die. What is amazing is that it never lost its leaves over the winter. I liked that

If I decide to repot though should I remove all the bad soil from its roots or as much as I can before setting it in new more appropriate(acidic) soil? Considering its bad shape is that something I should do ?

Is this good ?

https://www.rona.ca/en/product/cil-c-i-l-enriched-soil-3-in-1-bag-of-25-litres-2804521-89465036

i moved 1650 hosta in my z5 MI one winter.. and lost about 300 pots.. BECAUSE I DIDNT KNOW HOW TO DEAL with pots in late winter and spring..

your presumption that it thrived in the ground so overwintering in a pot should be easy squeezey.. is not kosher...

do NOT invest more money in this plant.. just go buy another.. though if your only option is potted.. then maybe you should try something other than a shrub...

if it is not dead.. its extremely stressed.. and fert is never a response to stress ...

i have no idea what peat moss will do .. buy or build an integrated medium or media.. we dont just add peat moss .. and if you used mother earth in the pot.. then winter drainage was the issue... and peat moss isnt going to fix it...[ btw.. most of us do not prefer any miracle grow mediums..]

never forget.. the most important thing in a pot.. is the media.. never the plant...

ken

Ivan, the product you've linked says 'Ideal for lawns and gardens'. It does not say its a suitable container mix. The two types are rarely interchangeable.

You seem to be in Canada so I'm not sure what's available to you under which brand names. You want a product recommended for growing maple, azalea, rhododendrons in containers if not planning on putting this back in the ground.

the plan is to put it back in the ground later when it is fully grown

The very reason why I moved the plant back to a pot/container was because I could not understand what was wrong with it. It was sitting somehow in full sun but still sheltered to a degree by ornamental grassed that would grown higher than the plant (at least for a while)

Re the product type suggested here: I would have to find that myself somehow -the staff at Homedepot or Lowes are useless these days...students who have no idea where things are on the shelf which is basic info to be able to work there, asking them what product to use for these is going to blow them a gasket :-))

Yes I am in Canada and having a hard time using those keywords on the Home Depot site

@ken_adrian Adrian MI cold Z5 I did not say the plant was thriving ("it did not thrive and it did not die") ...I was saying it survived the winter without losing leaves

PS: the plan is to put it back in the ground in a better (partial shade partial sun) place but I am not sure what is the procedure to prepare that spot. If this plant prefers acidic soil and my soil is alkaline (Clayish) then what do I do ? No matter how much acidic soil I put there in the beginning the root ball of the plant will outgrow that and it will end up reaching the alkaline soil again .... how does this work ?

" If this plant prefers acidic soil and my soil is alkaline (Clayish) then what do I do ? "

You pick another shrub to grow! Honestly, this is probably a very poor choice for your location. You are at the lower end of its hardiness zone and well below that for growing in a container. It requires an acidic soil and one that is consistently moist and well draining. At 5 years old plus, it is only a quarter of the size it should be and highly chlorotic, indicating it does not like its current growing environment.

I doubt it will ever grow to full size for you...it should already be 5 feet tall or more now.

If you do decide to carry on with this, look for a proper acidic potting soil at a decent nursery or garden center, not a box store.

Well I should go back to Lowes or Rona and nuke them for selling this if it is not meant for this area.

I don't like to give up on things (in particular on living things) so I will try to resurrect it :-)

" Well I should go back to Lowes or Rona and nuke them for selling this if it is not meant for this area. "

This happens all the time!! Next time, purchase any landscape plants at a proper plant nursery, not a home improvement store. And do your research before you buy!

They (the big nurseries) are not any better ..they should be nuked too.

Humber Nurseries which used to be a giant (they are still big in GTA) sold me a sango-kaku japanese maple This site is a living proof for how it died (posted around here in the previous years while trying to save it)

I think I found my soil

https://shop.sheridannurseries.com/products/fafard-acid-loving-plants-berries-soil-mix-30l

Should I completely or as much as I can remove the existing soil from the root system before repotting?

Is that Canadian hardiness zone 5a or USDA hardiness zone 5a? If the former, then for sure these plants are not well suited for your location and you should be doing significant research before you buy anything more. If the latter, you are also at the lower end of hardiness for both Pieris and Japanese maples.

Plants which are borderline hardy - and that would be those that are in the lowest zone of their hardiness range - are overly vulnerable to sharp shifts in weather patterns. Early frosts, late freezes or below normal temps for any length of time puts them at high risk for winter damage. You need to research your intended plants' requirements of growing conditions and tolerance levels to cold, heat/humidity and drought before you buy them .Do not rely on the nursery to provide all the answers for you.

It is 5a Canadian as shown here

http://planthardiness.gc.ca/?lang=en&m=24&s=p&speciesid=1000000&phz=phz1981-2010&bc=1

I think it's been too unhappy to ever become a graceful plant. It's hard to give up on a living plant, I hear you, but that plant's never going to be what it could have been. Perhaps you have plenty of space, and don't need every plant to look optimal? If so, I'd put it in the best, unimportant space I have, in the ground you have, and I'd water it until the plant looked like it was sending out new roots, making a go of it, then I'd maintain it with an acidic fertilizer. I did once inherit a Pieris growing in Brunswick, Maine, a U.S. Zone 5. That one thrived handsomely in acidic, very sandy soil with no care. I don't love Pieris, so it was on its own. That ridiculously sandy property, designated on geological maps with a pick and ax, grew beautiful acid-lovers.