Although they are native to the South, oakleaf hydrangeas can be grown as far north as the Ohio River Valley and into southeastern Pennsylvania (zone 5). Along the coastal areas they will survive winters into New England.
The Right Place
Although they are understory plants in their native areas, oakleaf hydrangeas are quite flexible about light conditions. They will tolerate a fair amount of sun as well as the light shade they are accustomed too in their native woodland settings. Those in sun often produce larger blossoms. They also need continuously moist, soil rich in organic matter for best bloom. They are fairly tolerant of sand or clay and alkaline soil, but prefer soil that is on the acid side (pH 5.0 to 6.5) and is well-drained.
Planting Nursery Stock
Although you can plant container-grown hydrangeas anytime during the growing season, spring is the best time because they have lots of time to establish themselves before frost. Choose ones that are 1 1/2 to 2 1/2 feet tall and that have two or three woody canes, if possible. Hydrangeas have shallow, fibrous roots and are easy to transplant.
Remove the shrub from its container and loosen any matted roots, gently spreading them. Keep the soil around them moist until planting time. Dig a saucer-shaped hole wide enough to accommodate the spread roots and just as deep as the container the shrub came in. Set the shrub in the empty hole, taking care that the top of the rootball is at, not below, ground level. Fill the hole with plain soil, firming it around the rootball with your hand to eliminate any air pockets around the roots. Water generously to provide good root to soil contact. Keep in mind the potential width of the shrub and allow sufficient open space around it. Do not fertilize at this time.
Amendments In Planting or Transplanting
There are a number of products at the garden center that will help your newly planted or transplanted plants deal better with the stress inherent in the planting process. All healthy plants have beneficial fungi, called mycorrhizal fungi, living on their roots. You can buy these valuable additions to your plant’s ecosystem. See the file describing Using Micorrhizae When Planting.
In addition, there are a number of products such as seaweed, compost tea, and beneficial soil microbes that when added to the planting process will help your newly established plants get going faster. See the file New Technology In Plant Growth Activators
For more information see the file on Planting Shrubs. For planting tools see Hand Tools For Digging and Planting in Yardener’s Tool Shed.