pieris japonica - can it recover from burns by cedar needles?

This past fall, I planted some small pieris japonica shrubs to provide nectar for mason bees (Osmia lignaria) in my garden during the early spring but they're doing very badly. Apparently I planted them too close to a cedar tree. Cedar needles fell on the back half of both pieris, making that portion of the plants turn completely brown and dry. I transplanted them a few days ago to a cedar-free location, added chicken manure to the soil around them, then mulched with rotting leaves. Does anyone know how hardy the pieris are? Will they survive that neglect/abuse? Will they be able to flower and provide nectar for the bees?

 

Highly unlikely to be the cedar needles causing the problem, Pieris normally do well under conifers. I'd suspect a fungal disease or insect damage of some sort. Can you post a photo of a damaged leaf?

 

Probably they got dried out under the conifer.

Like other heath family shrubs these prefer a moist porous soil with a comparatively low mineral content. I would lift them in their new location, remove the chicken manure amended soil and replant in the same soil that is all around the planting holes. If that soil appears to be unsuitable then you should probably bring in some suitable-looking soil and lay that onto the existing ground to form a berm or raised bed, plant in that. Be sure to mulch well afterward with a coarse material such as wood chips. Keep it well away from the stems.

Always plant with the same soil throughout the entire potential rooting area. Do not plant in pockets or zones of modified soil surrounded by different soil. The only exception is small-rooted plants like flowering annuals and vegetables which respond to high levels of organic matter and do not require a large area of soil.