How do I prepare sandy soil around the base of oak trees to plant flowers?
Oaks are sensitive to root disturbance, so it's best to plant in pockets rather than in large beds. Avoid disturbing more than about 1/4 of the root zone under the tree (less is better). And avoid cutting through roots that are larger than 2 inches in diameter. If the soil is quite sandy, it would help to add compost in the planting areas.