|I have a "Pieris Japonica" planted in partial shade. Leaves turn yellow and it generally looks sick. No vigor. Slow growth. Poor flowering. Can you give me some suggestions? Thank you.|
Pieris japonica prefers filtered sunlight or partial shade and acidic, well-draining but moisture retentive soil. If the foliage is yellowish, the soil conditions aren't quite right for it. Try feeding with an acid-based fertilizer (such as for rhodies or camellias), in amounts recommended on the label. You might also top-dress the soil beneath the plant with a little peat moss to help acidify the soil.
If the above suggestions don't improve the appearance of your Pieris, dig it up and inspect both the soil and the root system. You may find that the soil is too dry, too wet, or too heavy for good root growth. Check for healthy roots by snapping a few small roots in half. Healthy roots will be creamy white inside; dead roots will be either brown or rusty colored. Dead roots indicate overly wet or overly dry soils. Once you've determined the cause of the problem, you can correct it - even if it means transplanting your Pieris to a better location. Hope this information helps you help your plant regain its health!