Planting under maple trees is a challenge for several reasons. Most maple trees have shallow, aggressive roots. If you dig into the soil more than a few inches, you'll sever the roots, causing feeder roots to form and strangle any plant you place in the ground. If you provide water or fertilizer to only the plants, the tree's roots will invade that area in search of the moisture and nutrients. The secret to successfully planting under maple trees lies in selecting adaptable, small plants and treating the area as a whole, rather than catering to individual plants.