Planting for flood tolerance
Ensuring future green spaces can survive extreme climate conditions
Much of the conversation around future climate tends to focus on rising temperatures, drought, and water scarcity. These are important challenges, particularly for planting in urban environments where heat build-up and limited irrigation can place plants under stress. However, less attention is often given to the other side of this shift. Warmer air holds more moisture, and this leads directly to more intense and frequent rainfall events. As a result, flooding and prolonged periods of saturated soil are becoming more common across the UK.
Across the UK, rainfall is becoming more intense and less predictable. The start of 2026 highlighted this shift, with January recording well above-average rainfall across much of the country. In several regions, totals significantly exceeded long-term averages, leading to widespread waterlogging and localised flooding. These conditions are becoming part of a broader pattern linked to a changing climate.
This presents a different but equally important challenge for planting design. Landscapes must now cope with extremes at both ends of the spectrum, from drought to waterlogging, sometimes within the same year. Traditional planting palettes, which may perform well under stable conditions, can struggle when soils remain saturated for extended periods. Root systems can fail, plants may decline, and the overall structure of a scheme can be lost.
Looking ahead, climate projections suggest that winter rainfall in the UK is likely to increase further, with more frequent heavy rainfall events and a higher risk of flooding. This makes selecting plants that can tolerate wet conditions just as important an asset as plants that withstand drought.
Flood-tolerant planting is therefore becoming an essential part of resilient landscape design. By understanding how plants respond to saturated soils and selecting species adapted to these conditions, it is possible to create schemes that remain stable, functional, and visually consistent even during periods of prolonged rainfall.
The risks of flooding to planting schemes
Flooding places multiple stresses on plants. Waterlogged soils limit oxygen availability, weaken root systems, and increase the risk of root rot. Nutrients can be leached away, reducing soil fertility, while sediment movement can bury young plants or expose roots.
Repeated flooding can also destabilise planting schemes, particularly where species are not suited to wet conditions. Plants that struggle to establish in these environments often fail over time, leading to gaps in planting, increased maintenance costs, and reduced visual impact.
Selecting flood-tolerant species helps reduce these risks. These plants are better able to maintain growth, recover after flooding events, and contribute to long-term landscape stability.
What makes a plant flood tolerant?
Flood-tolerant plants are adapted to survive in soils that are waterlogged or periodically submerged. In these conditions, oxygen levels in the soil drop significantly, making it difficult for most plants to respire through their roots. Without oxygen, root systems can quickly fail, leading to plant decline or death.
Plants that tolerate flooding have developed ways to overcome this lack of oxygen. Some species form specialised tissues called aerenchyma, which allow oxygen to move from the leaves down to the roots. Others develop shallow root systems that remain closer to the soil surface, where oxygen is more available. Some species can even produce new roots above the waterline when submerged.
In addition to root adaptations, many flood-tolerant plants can slow their metabolic processes during periods of stress. This allows them to survive short-term flooding without permanent damage, resuming normal growth once conditions improve.
Strategies plants use to survive flooding
Flood-tolerant plants rely on several key strategies:
• Development of aerenchyma tissue to transport oxygen internally
• Ability to produce adventitious roots above water level
• Shallow or spreading root systems that avoid deeply saturated soils
• Slowed growth and energy use during periods of stress
• Flexible stems that tolerate water movement and sediment build-up
These adaptations allow plants not only to survive flooding, but to continue performing within challenging environments such as swales, rain gardens, and flood-prone landscapes.
Flood-tolerant plants for UK landscapes
The following plants are widely used in UK landscaping and offer strong performance in wet or flood-prone conditions.
Trees
Alnus glutinosa
A native tree well adapted to wet soils and river margins. Develops nitrogen-fixing root nodules, improving soil conditions over time. Tolerates prolonged waterlogging and stabilises banks in flood-prone areas.
Salix alba
A fast-growing willow suited to wet ground and floodplains. Flexible stems tolerate water movement, while extensive root systems help bind soil and reduce erosion.
Alnus glutinosa
Quercus URBAFLORA ‘Grace’
Salix alba
A fast-growing willow suited to wet ground and floodplains. Flexible stems tolerate water movement, while extensive root systems help bind soil and reduce erosion.
Taxodium distichum
A deciduous conifer adapted to standing water. Develops specialised root structures that assist with gas exchange. Suitable for sustainable drainage systems and water-edge planting.
Quercus URBAFLORA® ‘Grace’
A climate-resilient oak, selected for future urban landscapes. Being an English and Iranian oak hybrid, it combines drought and heat tolerance with the ability to withstand periods of flooding once established, making it ideal for environments facing extreme weather conditions. Its large, ornate downy leaves and hairy shoots enhance airborne particulate capture, improving air quality while supporting biodiversity. Part of Greenwood’s Climadapt range.
Shrubs
Cornus alba ‘Sibirica’
Performs well in damp and periodically flooded soils. Provides strong winter stem colour, adding seasonal interest alongside functional value.
Salix purpurea ‘Nana’
Compact willow shrub suited to wetter ground. Fine foliage and dense growth make it effective for stabilising soil in rain gardens and drainage areas.
Viburnum opulus
A native shrub tolerant of moist and heavy soils. Produces spring flowers and autumn berries, supporting biodiversity while coping well with seasonal flooding.
Cornus alba ‘Sibirica’
Salix purpurea ‘Nana’
Viburnum opulus
Perennials
Iris pseudacorus
A robust marginal plant suited to wet soils and standing water. Strong root systems help stabilise ground, while bright yellow flowers provide seasonal interest.
Carex elata ‘Aurea’
A moisture-loving sedge with bright foliage. Performs well in consistently damp conditions and is often used in swales and water-edge planting.
Filipendula ulmaria
A native perennial that thrives in damp meadows and floodplains. Produces soft white flowers and supports pollinators in wetter landscapes.
Iris pseudacorus
As rainfall patterns become more extreme, flood tolerance must become a key consideration in planting design. Selecting species that can cope with waterlogged soils helps create landscapes that remain stable, functional, and visually consistent despite challenging conditions.
Flood-tolerant plants help manage water, stabilise soil, and support biodiversity in environments that are increasingly shaped by excess rainfall. By integrating these species into planting schemes, designers can create landscapes that are better prepared for future conditions while continuing to deliver long-term value.
To find out more about flood tolerant plants for your projects, speak to the G Team today.