Why Won't Flowers Grow Under a Quaking Aspen?

Water

• Small flowering plants, whether annuals or perennials, have a tough time competing for water with the surface roots of a quaking aspen. The new plants need daily watering to thoroughly soak their roots and will require watering throughout the dry months. Figure on twice as much water as you would give a plant that isn't competing with a tree. Mulch around plants with 1 or 2 inches of compost, bark chips or dry grass clippings to slow evaporation.

Nutrients

• The quaking aspen's roots get first shot at any fertilizer you provide, so double the amount you give the new plants. Don't use a synthetic fertilizer, because doubling it can burn roots. Choose an organic fertilizer that releases its nutrients slowly, providing a steady nutrient source. Mulching with rich compost also adds nutrients.

Shade

• Most flowering plants need sun. If the canopy of the aspen is thick and little sun reaches the area beneath it, most flowering plants won't thrive. Perennials that grow in shade are a good choice for under trees, but choose those with attractive foliage, because bloom times for perennials are usually brief -- three to six weeks long. Annuals that do well in shade and bloom all summer include impatiens and tuberous begonias.

Planting

• Dig a generous hole for the plant and amend the soil with rich compost and a handful of organic fertilizer. If you encounter a large tree root, dig elsewhere. You can cut through small tree roots without worry, as they will produce new ones at the cut point. Water the new plant thoroughly to eliminate air pockets, even if it's raining or the soil is already moist.

Appropriate Plants

• Groundcover plants do well under trees, and some provide flowers. Lamium, vinca, ajuga, sweet woodruff and lily of the valley are drought-tolerant once established and bloom in late spring. Hostas grow into large, mound-shaped plants and produce lavender or white blooms in summer. Other flowering plants that thrive under trees include lungwort, lady's mantle, Japanese anemone, bleeding heart, coral bells and columbine.