Best Plants for Natural Swimming Pools and Swimming Ponds UK

The Living Heart of Your Natural Swimming Pool

Plants aren't just decoration in a natural swimming pool—they're the filtration system. Choosing the right species ensures crystal-clear water and year-round beauty for both formal natural pools and informal swimming ponds. Understanding the true cost breakdown helps you budget appropriately for plants—typically 5-10% of your total investment. Use our plant selector tool to browse UK-suitable species filtered by zone and light requirements.

Understanding Plant Zones

Plants work in tandem with the regeneration zone to keep water crystal clear. Natural swimming pools have distinct zones, each requiring different plants:

Zone 1: Deep Water (60cm+)

Submerged oxygenators that work invisibly beneath the surface.

Zone 2: Shallow Margins (0-40cm)

Emergent plants with roots in water, foliage above.

Zone 3: Bog Zone (Moist Soil)

Moisture-loving plants that filter water before it reaches the pool.

Essential Oxygenating Plants

These underwater champions do the heavy lifting in your natural swimming pool and are essential to the nitrogen cycle that processes waste naturally. For a complete guide to submerged plant species, see our detailed oxygenating plants guide:

Hornwort (Ceratophyllum demersum)

• Benefit: Exceptional nutrient absorption
• Depth: Free-floating or anchored
• Growth: Fast, may need trimming
• UK Native: Yes

Spiked Water-milfoil (Myriophyllum spicatum)

• Benefit: Dense foliage filters particles
• Depth: 30-100cm
• Growth: Moderate
• UK Native: Yes

Water Starwort (Callitriche stagnalis)

• Benefit: Year-round oxygen production
• Depth: 10-50cm
• Growth: Moderate
• UK Native: Yes

Beautiful Marginal Plants

These create the visual magic while filtering water in your natural swimming pool:

Yellow Flag Iris (Iris pseudacorus)

• Benefit: Strong nutrient uptake
• Height: 100-150cm
• Flowers: Bright yellow, May-July
• Zone: 0-25cm water depth

Purple Loosestrife (Lythrum salicaria)

• Benefit: Excellent filtration
• Height: 100-150cm
• Flowers: Purple spikes, June-September
• Zone: Moist to 10cm water

Marsh Marigold (Caltha palustris)

• Benefit: Early season filtering
• Height: 30-50cm
• Flowers: Golden yellow, March-May
• Zone: 0-15cm water depth

Water Forget-me-not (Myosotis scorpioides)

• Benefit: Excellent ground cover
• Height: 15-30cm
• Flowers: Blue, May-September
• Zone: 0-10cm water depth

Floating Plants

Surface plants that shade water and reduce algae:

Frogbit (Hydrocharis morsus-ranae)

• Benefit: Shades water, reducing algae
• Size: 3-5cm leaves
• Flowers: Small white, July-August
• UK Native: Yes

Water Soldier (Stratiotes aloides)

• Benefit: Excellent nutrient removal
• Size: 15-40cm rosettes
• Behaviour: Rises in summer, sinks in winter
• UK Native: Yes (rare)

Bog Garden Plants

The final filtration stage before water returns to your natural swimming pool:

Meadowsweet (Filipendula ulmaria)

• Benefit: Deep root filtration
• Height: 100-150cm
• Flowers: Creamy white, June-September
• Fragrance: Sweet, honey-like

Water Mint (Mentha aquatica)

• Benefit: Vigorous filtration
• Height: 30-60cm
• Flowers: Lilac, July-September
• Bonus: Aromatic foliage

Hemp Agrimony (Eupatorium cannabinum)

• Benefit: Butterfly magnet, good filtration
• Height: 100-150cm
• Flowers: Pink, July-September
• Wildlife: Excellent

Planting Guide for Natural Swimming Pools

When to Plant

For month-by-month timing, see our seasonal plant care calendar. When planning your pool, your designer will create a bespoke planting plan.

• Best: April-June
• Acceptable: March-September
• Avoid: Winter months — though the pool remains swimmable for cold water enthusiasts

Planting Density

• Oxygenators: 5-10 bunches per m²
• Marginals: 3-5 plants per m²
• Floating: 20-30% surface coverage maximum

Establishment Period

Allow 2-3 years for full establishment. Your natural swimming pool will improve each season as plants mature.

Plants to Avoid

Some species cause problems in natural swimming pools and swimming ponds:

Invasive Species

• Parrot's Feather: Extremely invasive
• Floating Pennywort: Illegal to plant
• New Zealand Pygmyweed: Chokes waterways

Problem Plants

• Duckweed: Spreads uncontrollably
• Reedmace (Typha): Too vigorous for most pools
• Water Hyacinth: Not winter-hardy in UK

Lume's Planting Plans

Every Lume natural swimming pool includes a bespoke planting plan featuring:

• Species suited to your location
• Quantities calculated for your pool size
• Seasonal interest throughout the year
• Wildlife-friendly native species
• Maintenance guidance

Use our plant selector tool to explore UK-native species and get quantity recommendations for your pool size.

See Plants in Your Pool

Understanding how natural pools stay clean helps you appreciate why plant selection matters. For ongoing care, see our maintenance guide.

Our AI visualisation shows how plants will look in your specific garden. Upload a photo to see your natural swimming pool brought to life.