How high to raise for hydrangea

[Dazed_Lily]

I'm going to plant hydrangeas(they are in small shallow 'holiday' pots right now) under a pin oak tree. I want to make a 'ring' with cement block. The block is 8 inches high. Would two tiers(16") be deep enough to support the hydrangeas and is there anything else I am overlooking ? ;)

[Tom]

Piling up 16" of soil on top of the roots of an oak tree has the potential of doing serious harm to the tree. Tree roots take in oxygen and you could suffocate them.

Oak trees are very thirsty in summer, and will compete with your plants for water, especially in dry periods.

You did not mention which cultivar you are planting so it would be difficult to advise on the amount of sun/shade they may tolerate.

Kerry Smith is our state Master Gardener coordinator at Auburn University. She has written an article on Hydrangea culture that you may glean some helpful information from:

http://www.ag.auburn.edu/hort/landscape/kerrysmith.html

[Dazed_Lily]

Oh boy ! I'm glad I asked if there was anything else ! I don't want to suffocate my pin oak. I love that tree. I actually have 2. They hold their leaves well past when they've turned brown and I love to hear the wind rustle the leaves when nothing else has leaves ! Thanks ! Oh, the hydrangeas are macro's and thank you for the link; I am slightly obsessed with hydrangeas--particularly saving holiday toss outs. (I even saw a droopy one in the floral dept of the grocery store this weekend and was very close to interrogating the clerk as to its fate; unfortunately she had a customer & I was on the way out).