Functional beauty for seasonally wet landscapes

Designing for boggy soils isn’t just a matter of drainage—it’s a matter of embracing the conditions and specifying plants that thrive in them. Whether it’s a low-lying basin, a swale, a detention zone, or an area with a high water table, there’s no shortage of places across NZ where water can linger longer than most plants will tolerate. But rather than fighting nature, we can lean into it with flowering plants that not only survive but perform beautifully in wet or seasonally saturated sites.

These are landscape plants, not pond plants. They’re for spaces that receive periodic wet and dry, such as rain gardens and bioswales that lack both drainage and irrigation. Flowering may be reduced during sustained wet if the plant needs to prioritise resources, but often they’ll flower strongly right through wet periods.

Grey Box™ Westringia ‘WES04’ PVR in full bloom during its flowering season. https://ozbreed.co.nz/plant-ranges/shrubs-and-ground-covers/grey-box-westringia/

Grey Box™ Westringia ‘WES04’ PVR outside of its flowering season in extreme wet. https://ozbreed.co.nz/plant-ranges/shrubs-and-ground-covers/grey-box-westringia/

The Problem with Poor Drainage

Waterlogged soils reduce the oxygen available to roots, creating anaerobic conditions that can quickly rot the crown or roots of most conventional shrubs and perennials. Many landscape failures are due to well-intentioned plants being put into sites where they simply can’t breathe.

For specifiers, this means that ‘bog-tolerant’ isn’t just a nice-to-have—it’s a critical design filter.

Why Flowering Plants Matter in Wet Zones

When it comes to water-prone areas, much of the focus tends to land on sedges, rushes, and wetland grasses—and rightly so, as they stabilise soil and handle inundation well. But there’s also a place for flowering shrubs, groundcovers, and even bold perennials to bring seasonal interest, pollinator value, and aesthetic cohesion.

• Visual interest in stormwater planting zones
• Pollinator habitat in marginal areas of parks and reserves
• Softening and transition at the edge of hard infrastructure
• Increased public acceptance of ‘messy’ or naturalistic plantings
  

With the right selections, even waterlogged spots can flower on cue. Some varieties may be reduced in flower during times of stress, such as after heavy rain events – the main thing is that they hold on through the seasonal wet until they can thrive once again.

Characteristics to Look For

Plants that flower in boggy soils tend to share some of the following characteristics:

• Adapted to seasonal inundation rather than constant standing water
• Tolerant of anaerobic soil conditions and root zone stress
• Often native to riparian, swamp, or wetland edge habitats
• Typically prefer full sun to part shade, where evaporation assists with drying

Importantly, not all wet-tolerant plants flower reliably—or attractively—so deliberate selection is key when aiming for ornamental performance. Remember to think beyond species level: you’ll find that varieties within the same species perform completely differently in the wet, so look out for reliable cultivars.

Macarthur™ Callistemon viminalis ‘LC01’ PVR bottlebrush flowers. https://ozbreed.co.nz/plant-ranges/shrubs-and-ground-covers/macarthur-callistemon/

How to Plant in Boggy Conditions

Even with the right plant, success depends on thoughtful installation:

• Raise crowns slightly above grade on shallow mounds or planting pockets
• Avoid planting into standing water—wait until soils are moist but not saturated
• Use coarse, open mulch like shredded bark to prevent compaction
• Incorporate organic matter only sparingly—over-enrichment can worsen root rot
• Space plants to allow air movement, which helps foliage dry between wet periods

Recommended Flowering Plants for Boggy Sites

• Slim™ Callistemon viminalis CV01′ PVR. https://ozbreed.co.nz/plant-ranges/shrubs-and-ground-covers/slim-callistemon/
• Better John™ Callistemon viminalis ‘LJ1’ PVR. https://ozbreed.co.nz/plant-ranges/shrubs-and-ground-covers/better-john-callistemon/
• Green John™ Callistemon viminalis ‘LJ23’ PVR. https://ozbreed.co.nz/plant-ranges/shrubs-and-ground-covers/green-john-callistemon/
• Macarthur™ Callistemon viminalis ‘LC01’ PVR. https://ozbreed.co.nz/plant-ranges/shrubs-and-ground-covers/macarthur-callistemon/
• Mundi™ Westringia fruticosa ‘WES05’ PVR. https://ozbreed.co.nz/plant-ranges/shrubs-and-ground-covers/mundi-westringia/
• Grey Box™ Westringia ‘WES04’ PVR. https://ozbreed.co.nz/plant-ranges/shrubs-and-ground-covers/grey-box-westringia/
• Evergreen Baby™ Lomandra longifolia subsp. exilis ‘LM600’ PVR. https://ozbreed.co.nz/plant-ranges/strappy-leaf-plants/evergreen-baby-lomandra/
• Shara™ Lomandra longifolia subsp. exilis ‘ABU7’ PVR. https://ozbreed.co.nz/plant-ranges/strappy-leaf-plants/shara-lomandra/
• Just Right™ Liriope muscari. https://ozbreed.co.nz/plant-ranges/strappy-leaf-plants/just-right-liriope/
• Amethyst™ Liriope muscari. https://ozbreed.co.nz/plant-ranges/strappy-leaf-plants/amethyst-liriope-muscari/

Conclusion

This curated list includes flowering varieties suited to New Zealand landscapes, all selected for their ability to tolerate wet soil while contributing to soil stability and biodiversity. Depending on a number of factors, flowering may be reduced in sustained wet conditions, or they may continue flowering right through wet periods.