pieris japonica isn't growing roots WHY?

hi everyone,
i bought a pieris japonica 'flaming silver' from lazy ss farm. it arrived in excellent shape, with a good root system. i loosened up the root ball, potted it into a larger container, set it in a part sun spot that i thought was ideal. watered it weekly. during the summer it lost most of its top growth and when i went to plant it now, in the fall, i see that it didn't grow any new roots at all -- in fact the root ball was substantially smaller than when it arrived.
what did i do wrong? i seem to lose rhododendrons like this too. does anyone know what i should do NOW to encourage the plant to live?
thanks so much, fellow gardeners!

You probably got a bit of root loss from transplanting....and I have read that P japonica can take a year or more to establish itself under near perfect growing conditions. Perhaps if you feed it with a bit of "RootStarter", a Phosphorus based aid for root production that may help.

Have you ever done a soil check to see what type of soil you have, the Pieris AND Rhododendrons all like an acidic soil so maybe when you plant this lovely shrub, you could buy some Acidic compost from the garden center and pot the plant up in this in a pot, you would need to do this now by the description of the plant and it's lack of growth tells me it needs urgent attention.
I would try gently wash off all the soil the roots are in and then re-plant it in the special compost, washing the soil will also let you check there is no bugs or anything eating the roots of the plant, there are some bugs that thrive on roots and in time the plant dies.
Hope this helps you out a bit. Good luck. Weenel.

"Loosening the root ball" means different things to different people. The loss of soil from the roots may have been excessive. And once they were loosened the backfill may have been too dry or wet and the soil may have been tamped in too hard, crushing the roots or too lightly, leaving air pockets. Subsequent watering may have been insufficient or excessive. There are some root balls that should be left quite intact and some that need severe trimming or unwinding. And every degree in between. Each rootball requires handling specific to its condition.

I whole heartily agree with all patti has suggested and still cant work out why Audrey loosened up the root-ball without have good reason to do this, however when we are not used to dealing with different plants and the different needs they require it is sometimes just trying to be kind to the plant that causes the problem.
I would still do a soil check as no mater what you do to the plants that are giving you a problem the wrong soil will kill off the plants no mater what you do to there roots, it's like trying to grow a Shrub Rose as a water plant in a pond, the rose will never make it sitting in water as what it really needs is a rich soil with added compost and a deep dug hole to allow the roots to bed into the soil.
The Pieris requires an acidic soil with added peat around the roots no mater what you do to help it grow / settle, without an acidic soil it will not do very good or may give up trying to survive all together and I would suggest this is the case in question, thats assuming no grubs were found in the soil eating the roots.
Good luck. WeeNel.

I have been engaged with a DGr that has the most skills ever in mixing your own soil. I have found that my soil in containers has been lacking and am working at improving that. I will attach the link for your review. Just remember it gets complicated but is worth a try.

http://davesgarden.com/community/forums/t/1226030/

It all began as "Beginner Houseplants".

This message was edited Nov 17, 2011 10:40 AM