Vinca minor, a low-growing evergreen ground cover, grows well in full or partial shade and under deciduous trees. Oak trees generally do not have shallow roots like other deciduous trees, such as maples, so planting vinca minor under the shade of an oak tree is an ideal location. Vinca minor is also called "periwinkle" but should not be confused with the annual plant by the same name. Vinca minor is usually planted in the spring after the last frost and will spread 1 to 3 feet depending on variety, so space multiple plants accordingly.
Turn over the soil with a garden fork or hoe under the oak tree where you plan to plant your vinca minor. Turn it over at least as deep and wide as the vinca's current container, but if you can, turn it over twice as wide and twice as deep. Watch out for roots and adjust the digging as you feel them or move to a different spot under the tree if there are just too many.
Mix into the soil about 25 percent more organic matter, such as compost or leaf mold.
Dig a hole in the amended soil as deep and wide as the vinca minor's current container.
Take the plant out of its container when the soil is slightly moist, plant the vinca minor and backfill the cultivated soil. Tamp down the soil to remove any air pockets.
Water your newly planted vinca minor with about 2 inches of water. Then continue watering to keep the soil moist for the first season.
Spread 2 to 3 inches of mulch, such as wood chips or bark, over the planting site to help retain water add valuable nutrients to the soil. Once the vinca minor fills in the space, you will not need to mulch.