Time of year
November through February is generally considered a good time to transplant Oregon Grape because the generally cool, moist weather decreases plant stress while the plant is developing a sturdy root system.
If you must move the plants now, considered rigging temporary protection against excessive wind and heat.
Supplemental irrigation is required during the first 2 years to increase the chances of survival for woody plants. This is true even for these drought-tolerant plants.
Thank you for your quick response. This will work. The area we want to transplant to sounds perfect. There are large pondo's overhead and smaller trees around. We can get irrigation to them also.