Landscaping around the base of trees can add beauty, suppress weeds, and retain moisture, creating a stunning and cohesive look for your garden. However, it’s crucial to approach this task with care to ensure the health and longevity of your trees. Improper landscaping techniques can severely damage a tree’s root system, leading to stress, disease, or even death.

The key to successful landscaping around trees lies in understanding their critical root zone (CRZ) and choosing the right plants and materials that coexist harmoniously.

Understanding the Critical Root Zone (CRZ)

A tree’s root system is often much wider and shallower than many people realize. The majority of a tree’s fine, water-absorbing roots are found in the top 6-12 inches of soil and can extend far beyond the tree’s drip line (the edge of its canopy). This area is the Critical Root Zone (CRZ), and it’s vital to protect it.

  • Avoid Deep Digging: Even small digs can sever crucial roots. Shallow-rooted plants and minimal soil disturbance are paramount.
  • Prevent Soil Compaction: Heavy foot traffic, machinery, or adding too much new soil can compact the existing soil, reducing oxygen and water availability to the roots.
  • Maintain Oxygen Flow: Tree roots need oxygen to survive. Piling excessive mulch or adding deep layers of soil can suffocate them.

Do’s and Don’ts for Landscaping Around Trees

DO’S:

  1. Assess Your Tree’s Health and Roots: Before you start, observe your tree. Is it healthy? Are there many exposed surface roots? For large, mature trees, roots can be extensive and sensitive. If in doubt, consult a certified arborist.

  2. Choose Shade-Loving and Shallow-Rooted Plants: The area under a tree is typically shady and can be dry due to competition from the tree’s roots. Select plants that thrive in these conditions and won’t compete heavily for moisture and nutrients.

    • Recommended Plants:
      • Hostas: Come in a huge variety of sizes, shapes, and colors, excellent for shade.
      • Ferns: Many varieties (e.g., Ostrich, Lady, Autumn, Holly Ferns) thrive in woodland conditions.
      • Coral Bells (Heuchera): Offer beautiful foliage in various colors and small flowers.
      • Astilbe: Provide feathery plumes of flowers in shady spots.
      • Periwinkle (Vinca minor): A tough groundcover that can suppress weeds.
      • Creeping Phlox/Thyme: Low-growing groundcovers that tolerate some shade.
      • Epimedium (Barrenwort): Delicate foliage and charming flowers.
      • Spring Bulbs: Crocus, Daffodils, Snowdrops can be planted under deciduous trees as they bloom before the tree leafs out.
    • Plants to AVOID: Those requiring full sun, deep roots, or frequent watering, as they will struggle and compete with the tree.

  3. Use Organic Mulch (Properly!):

    • Apply a 2-4 inch layer of organic mulch (wood chips, shredded bark, pine needles, compost) around the tree’s base.
    • Benefits of Mulch:
      • Retains Moisture: Reduces water evaporation from the soil.
      • Regulates Soil Temperature: Keeps roots cooler in summer and warmer in winter.
      • Suppresses Weeds: Blocks sunlight, preventing weed germination.
      • Adds Nutrients: Decomposing organic mulch enriches the soil over time.
      • Protects Trunk: Creates a buffer zone from mowers and string trimmers.
    • Proper Application: Spread mulch evenly, but ALWAYS keep it 2-6 inches away from the tree trunk to prevent rot, fungal growth, and pest infestations.

  4. Consider Container Plants: If you want seasonal color or have very sensitive tree roots, placing potted plants around the tree is an excellent solution. This avoids disturbing the soil and allows you to swap plants easily.

  5. Incorporate Hardscaping (Carefully):

    • Stepping stones, benches, or decorative rocks can add visual interest.
    • Place them on top of the soil or with minimal excavation.
    • Avoid placing heavy, large stones directly on roots or too close to the trunk, as they can compact soil and retain heat.
    • Gravel can be used, but ensure it allows water and air penetration and doesn’t get too hot for surface roots.

  6. Water Thoughtfully: While the tree will take much of the available water, new plantings will need supplemental watering to get established. Water deeply and less frequently to encourage roots to grow downwards.

DON’TS:

  1. NO “Mulch Volcanoes”: Never pile mulch high against the tree trunk. This is a common and harmful mistake that traps moisture, encourages pests, and can lead to bark rot.

  2. Avoid Adding Excessive Soil/Raised Beds: Adding more than a few inches of soil on top of existing roots can suffocate them by reducing oxygen exchange. Building raised beds around trees is generally discouraged unless they are very shallow (no more than 6 inches deep) and filled with a very light, well-draining soil mix, and even then, caution is advised.

  3. Don’t Cut or Sever Large Roots: If you encounter large roots while digging, do not cut them unless absolutely necessary and only after consulting an arborist. Root damage can severely impact tree stability and health.

  4. No Landscape Fabric/Weed Barriers: These materials can hinder air and water penetration, ultimately harming the tree’s roots and the beneficial soil organisms. Mulch is a far better and more natural alternative for weed suppression.

  5. Don’t Plant Too Close to the Trunk: Give the tree’s trunk a “breathing room” of at least 2-3 feet (or more for large trees) where only mulch is present.

  6. Avoid Chemical Herbicides: Using herbicides near a tree can harm its root system, as the chemicals can be absorbed through the soil.

By following these guidelines, you can create a beautiful, thriving landscape around your trees that enhances your garden’s aesthetic appeal while supporting the long-term health of your woody giants.