Shrubs and trees for a wet area

Where the ground is permanently wet, it is important to select plants that are suited because not all plants can tolerate these conditions. Those that are suitable may well surprise you by their vigor!

Shrubs and trees for a wet area

Particularities

The ground is always wet in areas that are close to a water course, at the bottom of a slope or near a spring. If you dig a hole, it will fill up with water especially between November and March. In summer the surface may dry out but deeper down say at 50cm, it will still be wet. The difference in water levels between the summer and winter is known as the variation. It can be as much as a metre. The soil in these areas is often rich and can be either clay or silt laden. There may also be the extra constraint of needing to retain the soil of the riverbanks or embankments.

The plants not to grow include those that cannot survive not having air around their roots. As the ground is sodden with water, plants with fine roots will suffer and die. Evergreen shrubs like the Oleasters (Eleagnus) and Olearia are particularly sensitive. However, plants whose roots tend to be near the surface rather than deep such as Willows are better adapted. Perennials with large spongy roots like the Water Iris (Iris pseudoacorus) have the peculiarity of being able to breathe internally. They are therefore totally at home in wet ground.

Shrubs and trees for a wet area

What to choose ?

Riverside plants are also called "paludal" and have the ability to flower in the marshes. The Ethiopian Arum Lilly (Zantedeschia aethiopica), Goat’s Beard (Aruncus), Astilbes, Hemerocallis and Giant Yellow Cowslip (Primula florindae) are some of the easier to grow flowers in these conditions. If the spot is shady, then there is less choice and it is best to concentrate on plants with nice foliage like ferns, Carex and variegated grasses. As for trees and shrubs the choice is even less but there are still a few possibilities. Alders, different types of willow and other varieties suited to wet ground (Swamp Cypress, Marsh Oak) will all grow quickly in wet ground.

Points to remember

It is tempting when you plant a tree in wet soil to add a layer of gravel in the bottom of the hole to improve the drainage. This is a bad idea because the water will accumulate and the tree will permanently sit in a pool of water! Better to break up the soil down to a good depth using a pickaxe. However if the species being grown is not suited to wet conditions then it is a waste of time anyway. Remember to solidly stake any young trees and shrubs, as there is more chance of them being flattened during a storm because the soil is soft.

M. Jean-Michel GROULT
 
Pépinières PLANFOR
1950 Route de Cère
40090 UCHACQ - FRANCE
Tel : (020).7660.0178
Fax : 0033 558 064 854