Oak trees can be very large, sometimes reaching up to 100 feet tall. Under the canopy of an oak tree, some plants sometimes have a difficult time surviving. But many other plants grow and thrive in that shady area.
It is better to grow perennial plants under an oak tree, so you are only planting them once, rather than every year like you would for annuals. Root disturbance for the tree is kept to a minimum, plus the tree and plant roots will adapt to one another over the growing seasons and learn to co-mingle.
Select plants that are in small containers at planting time. Plants that are potted in 2-1/2 to 4-1/2 inch pots will require less digging. Plants can reach a larger size as they grow and mature; however, keep in mind the mature height of your plants and compare it to the lowest branches of your oak tree. Plants should not grow too close to the branches or it may look awkward. Grow the tallest plants closest to the boot.
Shade- and Drought-Tolerant Plants
Plants under an oak tree must be shade-tolerant and moderately drought-tolerant. The ones closest to the boot will get some sunlight in the spring before the leaves form, but after that, they will receive little, if any, sunlight. Plants growing near the canopy will receive more sunlight, especially on the southern side of the tree. Since the oak tree will compete with the plants for water, they must be able have moderate drought-tolerance.
Examples of Plants to Grow
Some plants to consider under an oak tree are wild lilacs, snapdragons, alums, monkeyflowers and fuchsias. Ground covers that may fare well under your oak tree are wild ginger, periwinkles and lily of the valleys. Bulbous plants that may thrive in the shade under an oak tree are daylilies, coral bells and bell flowers.