For landscaping under oak trees, choose plants that enjoy shade and are drought tolerant. Most grasses will not be suitable for this task. Creating an understory bed of perennials or small shrubs is your best bet. Avoid planting too close to your oak tree’s trunk unless you are using very small or shallow rooted plants. Even with smaller plants, be sure that you dig gently to ensure you aren't hitting your tree’s roots. Let’s beautify gently! Be sure not damage any roots when planting.