Gatsbys are usually quite large specimens but that might change due to your location. Hydrangeas will not complain if given morning sun only.

If they do not complain during your summers then yes, try full sun as that will result in a great Fall foliage show. I recommend growing in a pot then during its first full sun year. If the leaves do not show signs of sun scorch inn Summer 2019, plant it afterwards. Keep the pot protected in the winter though.

Thank you Luis.
I am hoping this oakleaf will get to 8x8’, but perhaps that may take 5 yrs?
I bought the 3G proven winners pot and have had it in 5+ hours of sun this summer as a trial. Seems to be fine. I’m hoping to get it into the ground soon (once I decide on the perfect spot) because I won’t be at this cottage over the winter very often if I kept the pot in a shed. I’m really looking forward to the fall foliage change too!

Yes, it may take "a while". It is a "new" hydrangea so take the size estimates with a grain of salt. Decide on the perfect spot and plant/mulch it soon since your winters are harsh in Zone 5.

Give it plenty of mulch, 2-4" (5-10cm) and, provided the soil has not frozen yet, water deeply the night before temps go down a lot below freezing.

Oakleaf hydrangeas will quickly develop root rot if their roots spend a lot of time in water so make sure the soil drains the water well or moves excess water away. I had an Alice Oakleaf in a bad spot and lost it in my first year with the plant and in the house. I had no idea that if it rained a lot, water would collect in the selected location. Then we got an El Nin~o and it rained 1-3" at least once a week from March thru June-July. Somewhere in May maybe, I lot that specimen. Probably lasted 2-3 months.

The foliage show that oakleaf hydrangeas produce is excellent but they need a few hours of sun at least to produce nice purples, oranges and red... and of course, cooperative weather from Mother Nature. We are having an El Nin~o again now and these last few months have been awfully cloudy; not sure how my oakleafs' show will be this time around. Make a note in a wall calendar as to when it starts so you will know in future years; do the same for leaf out time.... That last one is tricky here. Depending on how much protection the location of my oakleafs provides for them and depending on how mild winter is, they may not loose foliage during Fall or Winter.

https://carolynsshadegardensdotcom.files.wordpress.com/2012/05/dscn1640.jpg

https://plantaddicts.com/product_images/uploaded_images/oakleaf-hydrangea-foliage-changing-colors-compressor.jpg

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