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From: Evansville, IN
Region: Midwest
Topic: Shrubs, Trees
Title: Rhododendrons Hydrangeas in Indiana
Answered by: Candace Fountoulakis
Rhododendrons and hydrangeas both require light, well-drained soils but don't appreciate drying out. They also need an acidic soil, with a pH of 5.5 being ideal. A soil test of the areas where your shrubs are planted will determine if the plants will ever thrive. Amending soil whose pH is not low enough to suit these types of plants is not a reasonable long-term solution. A loose but deep mulch with no other competition from plants other than the trees would also help these shrubs. The foundation can add to alkalinity problems as well as cause iron chlorosis. The soil test would also indicate this if samples were taken from that area. I don't know what effect the grainery would have other than to cast shade or perhaps indicate compacted soil in the area that would inhibit root growth.
If your soil tests determine that the pH is not in the range that these shrubs prefer, I would suggest some similar blooming native shrubs that would do well and bloom in the conditions you describe. I have attached links to these plants so that you can see how beautiful these native shrubs could be.
Hydrangea arborescens (wild hydrangea) (PHOTO BELOW) Cornus racemosa (gray dogwood)
Cornus sericea (redosier dogwood) Itea virginica (Virginia sweetspire)
Viburnum dentatum (southern arrowwood) Viburnum opulus (European cranberrybush)
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