We have suggested the notion that most plants don’t like being saturated or sitting in moisture which is true although there are a handful who do. These plants were intended for water and need to be submerged in it. Often known as oxygenating plants, these plants keep unhealthy algae and weeds in abeyance. Certain plants are equally effective in improving the aesthetics of eyesores and providing habitat for aquatic/insect life.
There are cultivated plants you would expect from irises to water lillies although there wild, native (UK) varieties that deserve a mention. Marsh marigolds (Caltha palustris) are clump forming, providing yellow cup shaped flowers from spring to summer. The plant provides a food source to beneficial insects encouraging bio diversity. The plant likes sun but can be found in woodland areas so tolerates partial shade.
Creeping jenny (Lysimachia nummularia “Aurea”) – although this is a ground cover plant it grows on land and in water. Low growing dense foliage providing shelter and coveting undesirable edging. It flowers from June to September providing pollen to bees. It copes very well in moist soil and marsh-like conditions. The plant will filter the water as it floats. It can be invasive but is straighforward to keep under control. The unwanted growth simply pulled out.
Marsh woundwort (Stachys palustris) – a perennial that flowers usually in June to August providing an essential food source. This marginal plant has attractive pink purple flowers that encourage birds and aquatic life too. Its roots sit just under the surface of the water as opposed to being submerged but resilient from damage if disturbed. It usually does well on low, damp ground.
Water hyacinths (Eichhornia crassipes “Lillianes”) are not native to the UK. The plant can be found in C. America/Southern climes and effectively used to purify the water. The resilience to adverse conditions of Ph, temperature and nutrients are why the plant is used. This and attractive flowers and foliage. However, what it is also known for is being particluarly invasive in more ways than one. Above the surface is a impressive show of flowers and foliage. Underwater, the roots are said to damage pumps, liners, filters and potentially wipe out other neighbouring species including wildlife – insect or aquatic. A pause of caution then.
Water lillies (Nymphaea) – although the roots sit underwater, the plant usually requires some growing medium in a submerged basket as opposed to rooting wherever it can. The leaves are built to resist damage and the waxy surface to ensure they’re not over doused in water. A tip is to adhere to the depth requirements as varieties differ and can strongly determine the plants success. These plants will need to be divided at some point. Lillies do have a tendency to become congested in time. An indication can often be if the flower protrudes from the surface.
Irises are a perennial that can survive and thrive in boggy/marsh-like conditions. Others can be semi-aquatic. The Blue flag (Iris versicolour) is an aquatic variety, the Yellow (Iris pseudacorus) can be found near water although will cope with drier conditions. Iris sibirica, a purple variety provides long lasting blooms but usually are found on harder terrain. The plant still needs moisture but not so much wetlands. Flowering times of irises are spring to early summer with beardless ones usually slightly later. All Irises will benefit from division. It will improve the plants performance and health. In flower, do deadhead the plant since this will prolong the blooming period giving it a show for longer.
The Umbrella plant seems to fuse its purpose to both the garden and house. It is used as a pond plant and some care is needed as the plant is developing its roots system, but when established can withstand moist and wet conditions. It can be immersed in water and grown in soil. Cyperus alternifolius, a grass like perennial providing interesting foliage which will die back in winter. It’s not frost hardy, so in a pot needs protection from the elements. It likes a sheltered position, but does need some natural light too. An ideal soil would be wet and humus rich. It can equally be grown indoors as long as these conditions of medium, moisture, space and temperature are adhered to.