Page 126 - Luton SuDS DESIGN & EVALUATION
P. 126

Detailed Design  9.10.3.3 Wetland & pond planting           Autumn and winter planting of wetland

           The biology of ponds and wetlands is similar,
           but not identical. One definition suggests
                                                                  plants often fails to establish well and they
           that ponds have around 75% open water and
                                                                  tend to be uprooted by water or wind. Plant
                                                                  in spring or early summer wherever possible.
           wetlands around 25%.

                                                                  Where wetland plants are being used where
           The planting requirements are very similar.
                                                                  people are often present e.g. housing, visually
           Wetland habitats are very sensitive to
           invasive plants and therefore unless the SuDS
                                                                  enhance acceptability by the community.
           are part of an enclosed urban situation native         attractive native plants can be selected to
                                                                  Flag iris (Iris pseudacorus) and Purple
           wetland plants should be used in planting
                                                                  Loosestrife (Lythrum salicaria) are examples
           proposals and should be obtained from an               of plants that add attractiveness to waterside
           accredited source with confirmation that the
                                                                  planting.
           aquatic nursery is free from alien and invasive
           species.                                               Wetland and pond planting design criteria:

           Wetland plants can be divided into 3                      ■  Selection of aquatic plants should
           categories:                                               normally be native, and a mix of emergent
              ■  emergent plants that tend to grow                   and spreading plants.

               vertically around the edge and into the
                                                                     ■  In urban design some ornamental planting
               water depending on its depth
                                                                     may be justified but not where there is a
  121         ■  spreading plants that tend to grow                  risk of direct links to the natural
               horizontally around the edge and into the             environment.
               water depending on the depth

              ■  water plants that grow in the water
               column either anchored by roots or free
               floating.

           These plants are usually planted at 5 or 8

           plants per square metre or as a linear edge to
           wetlands. Wetland plants grow vigorously in
           spring and through the summer with growth
           slowing as autumn approaches.





                                                        Design Note:
              Reedmace (also called Bulrush or Typha latifolia) can seed rapidly on exposed mud edges.
            This colonizing plant should be considered a potentially dominating weed until a diverse plant
                                                 community is established.



           Luton Borough Council SuDS D & E Guide                                                              © 2018 McCloy Consulting & Robert Bray Associates
   121   122   123   124   125   126   127   128   129   130   131