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Thursday - December 13, 2007

From: Evansville, IN
Region: Midwest
Topic: Shrubs, Trees
Title: Rhododendrons Hydrangeas in Indiana
Answered by: Candace Fountoulakis

QUESTION:

I live in very southern Indiana. Our home faces west and at the front of our home I have planted three rhododendrons. The furthest south is growing well the two to the north not so well. All three have bloomed only once,(the second year) with only a few blooms each. They have been there about 5 years. Large trees filter the late afternoon sun. Also, I have planted three hydrangeas on the north side of the house within 2 feet of the foundation, also in afternoon shade. A huge chestnut tree filters much of the sun and a big old grainery that sits on the north side of the house blocks most of the sun. I have not provided acid due to the acidity of oak leaves and I assume chestnut leaves. Can you help me with these two beautiful plants. I am not opposed to moving them if need be but need recommended species for the areas that they are located in now.

ANSWER:

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)

 

From the Image Gallery


Smooth hydrangea
Hydrangea arborescens

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