Page 124 - Bexley SuDS DESIGN & EVALUATION

Detailed Design 9.10.3.2 Herbaceous planting Herbaceous planting, as well as fulfilling the

Raingardens and bioretention features, in
functional and aesthetic criteria of more
particular, use herbaceous plants and
sometimes low shrubs to create an
general soft landscape design, must protect
the SuDS network, by means of the following
ornamental appearance or planting that is
appropriate to a formal landscape context.
criteria:

■
Flowing water can be a constraint to the
The planting must resist flow, encourage
planting of SuDS features. Raingardens and
bioretention are examples of smaller basin
collectively be attractive all year.
structures with less dramatic flows that allow ■ the trapping of silt and pollution as well as
Unlike general amenity planting, the
an ornamental planting approach to be taken.
planting must be either evergreen or have
This is helped if there are inlet aprons or
a presence at ground level year-round.
other erosion controls where water enters the
feature. ■ Plant selection must take into account
that the raingarden will be dry most of the
Plants can be evergreen (e.g. Geranium
time and although it will be inundated in
macrorhizum and Phlomis russeliana) or
most rainfall events will usually return to
plants that shrink back to a visible clump (e.g.
empty within around 24 hours.
Alchemilla mollis and Rudbeckia fulgida

‘deamii’) or with winter-present foliage such ■ Herbaceous plants should be selected
as grasses like Miscanthus and Stipa. This with a fibrous root system to hold the soil
119 planting usually needs a minimum of one together.
strim in February and some weeding during
■ Planting choice should avoid the reliance
the growing season.
on herbicides, pesticides and fertilisers to
protect receiving watercourses.

London Borough of Bexley SuDS D & E Guide © 2018 McCloy Consulting & Robert Bray Associates