horsley witten group, inc. public workshop vegetation management and maintenance january 19, 2011...

Horsley Witten Group, Inc.Horsley Witten Group, Inc.

Public WorkshopVegetation Management and

MaintenanceJanuary 19, 2011

Rhode Island Stormwater Design and Installation Standards Manual


Introduction

• Plant Design

• Plant Selection

• Plant Care


• Establish a preferred design approach

• Understand site constraints and conditions

• Select appropriate plant species

• Prepare planting design plan

• Keep it simpleSource: http://plants.usda.gov

Design Basics


Planting Plan


Scheduled Maintenance


Pruning and Plant Thinning• Why Prune?

– Maintain plant health and vigor

– Removal of dead or broken wood

– Encouragement of flowering and fruiting

– Control of overgrowth of plant material

Image courtesy of Rutgers New Jersey Agricultural Experiment Station


Pruning and Plant Thinning• Trees and large

shrubs

– Wait at least 1 year– Remove dead,

damaged, or diseased branches only

– Prune in late winter/early spring

– Never prune behind the branch’s bark ridge


Pruning and Plant Thinning• Shrubs

– Prune once the shrub approach mature height

– Immediately after flowering, unless specified otherwise

– Pruned back damaged/diseased limbs

– Do not leave stubs


Pruning and Plant Thinning• Perennials and

grasses

– Leave dry standing stalks during dormant months

– Cut back dead foliage late winter/early spring

– Remove cut foliage from bioretention area


Mowing

• Not necessary or recommended for raingardens/bio.

• Allow plants to flourish

• When side slopes seeded with native grass– Mow once or

twice per year


Mowing• Use a mulching

blade or point the mower away from the bioretention area

– Fresh grass clipping are high in nitrogen

– Grass clippings can compromise pollutant removal effectiveness


Mowing


Weeding• Why Weed?

– Control invasive plants

– Promote native non-invasive plant growth

• When to weed?– April thru

October– Monthly


Weeding• Do not use chemical

herbicides

• Remove by hand

• A list of invasive species can be found at:http://www.rinhs.org/resources/ri-invasive-species-resources/invasive-list/


Weeding• Be on the lookout for these invasive species:

Oriental Bittersweet

Japanese Knotweed

Photo by Betty Ann Kelly


Weeding• Be on the lookout for these invasive species

Multiflora Rose

Scotch Thistle


Photo courtesy of Rutgers New Jersey Agricultural Experiment Station

Watering• During the first

few weeks after planting– To establish

and maintain healthy grass

• During the 1st year – Plant and grass

growth

• After the 1st year – Drought

periods only

Soaker hose


Disease and Pest Control• Monitor plants for

damage

• Pesticides should be avoided

• Adopt an Integrated pest management approach– Biological– Physical– Mechanical– Cultural – Chemical controls


Plant Replacement • After the first season, look for the following plant

health indicators:

Photo by Linda Brazaitis

– Was the weather drastically different than the conditions the basin was designed to retain?

– Was flow too fast through the basin, damaging health?

– Is flow being incorrectly discharged from the rain garden?


Plant Replacement• Replace dead or

diseased plant material

• Place plant in the same location

• Re-seed the side slopes

• Best time to replant:– Early to mid Fall– Early to mid Spring

Photo courtesy of Rutgers New Jersey Agricultural Experiment Station


The first Rain Garden in Virginia, located in a turning circle in front of St. Stephens School,

Alexandria.


St. Stephens Rain Garden- 5 years later.


2000

2003

It doesn’t takelong


Fertilizing• Fertilization should

not be necessary

– Compromises pollutant reduction effectiveness

– Leads to weak plant growth

– Promotes disease and pests

– Inhibits soil life


Questions?

horsley witten group, inc. public workshop vegetation management and maintenance january 19, 2011...

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