NZ Native Plants for Banks, Cliffs and Steep Hills — A Complete Guide

Why Banks & Steep Hills Matter — and Why Choose Natives

Banks, gullies, and steep hillsides — whether on rural land, garden slopes, roadside embankments or hills — pose particular challenges for planting and landscape stability. The main challenges include:

• Slope & Exposure: steep angles make soil prone to sliding or erosion, especially in heavy rain or runoff.

• Soil Conditions: soil is often shallow, rocky or free‑draining — prone to drying out or washing away.

• Water Dynamics: some slopes may be very dry and exposed; others may channel runoff or seep, leading to variability in moisture.

• Erosion Risk: without stabilising vegetation, soil can be lost downhill, affecting both garden stability and environmental health.

Many exotic garden plants struggle under these conditions: roots may fail to anchor in shallow/rocky soil; dense soils may waterlog; shallow roots don’t grip loose soil; maintenance can be high. By contrast, New Zealand native plants often evolved on hillsides, gullies, and slopes — developing deep or fibrous root systems, drought or variable‑moisture tolerance, flexible growth habits, and an ability to stabilise soil. Planting them on banks or hills not only helps with stability, but also builds resilience, low‑maintenance landscaping, and support for native biodiversity.

Choosing What to Plant: Match Plants to the Bank or Hill Type

Different kinds of slopes and hillsides benefit from different plant types, depending on soil, exposure, and moisture. Below are common slope‑scenarios and recommended natives.

Dry, Exposed Slopes & Hillsides

Challenges: full sun, wind, low or shallow soil fertility, fast drainage, drought risk.

Good native plant choices:

• Corokia cotoneaster — an excellent choice for dry, exposed slopes and hillsides.
  
  

• Austroderia richardii (Toetoe) — handles windswept, dry sites well.
  

• Hebe albicans — a tough shrub that loves exposed sites.
  
  

• Carex testacea — warm, coppery, drought-tolerant sedge perfect for slopes.
  
  

Moist Slopes, Gullies & Stream‑Bank Edges

Challenges: variable moisture — may be damp, experience runoff, or have water seepage; soil may shift or wash with water flow.

Good native plant choices:

• Chionochloa rubra / flavicans — tolerant of shallow soils and windy slopes.
  
  

• Astelia chathamica  — strong, fibrous root system and robust clump form help stabilise soil exposed to water flow or occasional soggy conditions.
  
  

• Coprosma robusta — tough shrubs that tolerate variable moisture and help anchor soil on gullies or moist slopes.
  
  
  

Rocky, Shallow‑Soil Slopes & Hillside Outcrops

Challenges: thin or stony soils, poor water/ nutrient retention, exposure to wind and sun, limited root depth.

Good native plant choices:

• Coprosma kirkii — spreads densely, good root mat, handles exposure.
  
  

• Cordyline australis (Cabbage tree) — surprisingly tolerant of rocky, exposed hillsides.
  
  

• Hebe pinguifolia — very hardy, rock-loving shrubs.
  
  

Mixed‑Planting for Stability & Ecology (Mixed Banks / Steep Gardens)

When soil depth, moisture, or slope varies across a site, a mixed planting approach works best:

• Combine grasses/tussocks at base (for anchoring soil), mid‑height shrubs for bulk and structure, and hardy small trees or shrubs for upper slopes or wind‑exposure.

• Use layered planting — groundcovers, grasses, shrubs — to mimic natural slope vegetation; this maximises soil stability, moisture retention, and ecological value.

Signature Bank & Hill‑Friendly Native Plants

Here are some of the most reliable and widely used native plants for banks, gullies, slopes, and steep hills — known for strong root systems, tolerance to exposure, and soil‑binding capacity:

• Kānuka ( Kunzea ericoides ) — deep‑rooted pioneer shrub/tree for dry slopes and exposed hillsides.
  
  

• Mānuka ( Leptospermum scoparium ) — hardy shrub that establishes quickly and stabilises sloping ground.
  
  

• Tauhinu ( Ozothamnus leptophyllus ) — useful shrub for dry, marginal, or shallow soils on slopes or rocky terrain.
  
  

• Silver tussock ( Poa cita ) — a tussock grass that grips soil and reduces erosion on slopes.
  
  

• Tall sedge / Makura ( Carex secta ) — ideal for wetter banks or slopes with runoff / seepage.
  
  

• NZ Flax ( Phormium tenax ) — versatile plant for moist gullies, stream banks, or slopes with variable soil.
  
  

• Shrubby natives (e.g. tough Corokia, Coprosma species) — useful for shallow soil or mixed slope plantings, adding structure and erosion resistance.
  
  

Practical Planting & Care Tips for Banks & Steep Hills

1. Site Preparation & Soil Stability

   • If planting on a slope, dig “shelves” or contour terraces/steps rather than planting straight up/down — this helps slow water runoff and gives roots a chance to anchor.

   • Loosen soil carefully without over‑disturbing natural structure — too much disturbance may loosen topsoil further.

   • Where soil is poor or shallow, mix in coarse material (gravel, sand) or small stones to improve drainage and help plants anchor.

2. Erosion Control During Establishment

   • Use biodegradable erosion control matting or light netting on steeper slopes to hold soil until plants establish.

   • Mulch carefully — avoid heavy mulch that may slide; use coarse, stable mulch (e.g. small gravel, bark chips) and keep mulch slightly cleared around stems.

   • Space plantings relatively densely (especially ground‑covers and tussocks) to minimise bare soil exposure, but allow room for growth.

3. Watering & Care of New Plantings

   • On dry slopes: water regularly during establishment to help roots establish before summer heat.

   • On wet or gully slopes: ensure good drainage, especially mid-slope, to avoid waterlogging; avoid planting in obvious water channels that may enlarge during heavy rain.

   • Monitor for signs of wash-out or soil movement — if runoff is strong, consider bunds, terraces, or diversion measures to protect plantings.

4. Long-Term Planting Strategy

   • Use mixed plantings — grasses/tussocks at base, shrubs in middle, small trees or hardy shrubs at top — to create a stable, layered slope vegetation.

   • Over time, let native plants self-seed or fill in gaps rather than aggressively pruning or standardising — natural diversity helps soil and ecosystem resilience.

   • Avoid over-fertilising or heavy soil amendments; many slope‑adapted natives do best on lean, free‑draining soils — rich soil can encourage shallow, weak-rooted growth that is less stable.

5. Maintenance & Monitoring

   • Check regularly — especially after heavy rain — for signs of soil slippage, erosion, or bare patches.

   • Replant or reinforce areas where soil has been disturbed or lost.

   • Keep weeds under control during early years — exotic weeds often outcompete natives on disturbed slopes.

6. Long-Term Benefits

   • Well-chosen native plantings greatly reduce erosion risk, stabilise slopes, and provide long-term structural integrity.

   • As plants mature, they become low-maintenance — deep roots and adapted physiology mean less watering, fertilising, or upkeep.

   • Native slope plantings enhance biodiversity: they provide habitat for native birds, insects, and other fauna, restore natural vegetation patterns, and help maintain ecological health.

Planning Your Bank or Hillside Planting (Anywhere in NZ)

1. Survey the Slope or Bank

   • Note slope angle, soil type (rocky, sandy, clay, shallow), drainage behaviour, sun exposure, wind exposure, and moisture patterns.

2. Classify Your Slope Type

   • Is it a dry, sun‑exposed slope, a moist gully or runoff-prone bank, or a rocky shallow‑soil hillside?

   • This helps choose the right plants and planting strategy.

3. Select a Diverse Mix of Plants

   • Use a combination of tussocks/groundcovers, shrubs, and (where appropriate) small trees or larger shrubs — varying root depths and growth habits improves slope stability and ecological resilience.

4. Prepare Soil & Plant Thoughtfully

   • Where needed, improve drainage, add coarse material, or build simple contours/terraces for very steep ground.

   • Use mulch or erosion‑control matting to protect soil until plants are established.

5. Plant at an Appropriate Time

   • Aim for late winter to early spring (or early autumn) — cooler, moister conditions help roots establish before summer drought or winter storms.

6. Care During Establishment, then Step Back

   • Water and monitor plants in the first 1–2 seasons.

   • Once established, native bank plantings typically need little maintenance — they adapt to local conditions, stabilise soil, and often self‑seed.

7. Allow Nature to Do the Work

   • Over time, a mix of stabilising grasses, shrubs, and woody plants will develop — creating a self‑sustaining, erosion‑resistant slope that supports native biodiversity and requires minimal upkeep.