Flood-wise landscaping

Reduce potential flooding with the landscaping design of your outdoor space.

On this page

• Who should take action
• What it is
• Benefits
• What you'll need
• What's involved
• Cost
• When to do it
• Be flood ready

Who should take action

• Homeowners
• Landlords and property managers
• All homes with coastal, rainfall, and riverine flood risk
• Most important for homes with:
  • yards, driveways, decks and patios at ground level
  • poor exterior drainage, such as property grading that leads water toward the home

What it is

Flood-wise landscaping includes changing elements of your outdoor space to protect from potential flooding. This will increase your home's flood resilience.

Water follows the path of least resistance. Flood-wise landscaping helps guide water away from your home.

Common flood-wise landscaping options for homes include:

Plants, trees and rain gardens

• Trees, shrubs, bushes, and flowers act like natural sponges that absorb rainfall, ice and snowmelt (runoff) that could otherwise pool around your property or enter your home
• Rain gardens are specially designed gardens with a layout and plant composition designed to collect and store large amounts of runoff
  • Rocks stabilize the soil and help slow down the flow of water
• Bioswales are vegetated drainage ditches that are similar to rain gardens, but larger
  • They can be installed in ditches on or between properties to capture runoff and improve drainage
• Green roofs and vertical gardens are other ways to manage rainfall
  • These may be used in high-rise buildings and homes without yards

Permeable pavements

Permeable pavement is a type of pavement with high porosity, or gaps. This allows water to soak into the underlying soil instead of sliding off the surface and collecting in low-lying areas, as with completely paved pavements.

Benefits

This is a high impact action that can greatly reduce the impact of a flood on your home and save you money over the long term.

• During heavy rainfall and localized flooding, well-planned landscaping can provide peace of mind
• Rain gardens can absorb 30% more water than a lawn of the same size
• Rain gardens, bioswales and rocks prevent erosion and reduce the amount of water that might reach your home
• Permeable pavement allows water absorption into the soil below and improves drainage around your home
• Permeable pavement reduces the amount of road salt needed to keep surfaces clear in the winter time

Flood-wise landscaping can:

• enhance the quality of stormwater runoff
• reduce the risk of localized flooding by slowing and redirecting runoff
• increase the attractiveness and environmental benefits of your yard, including providing habitat for pollinators

What you'll need

• Tools or materials for gardening
• A rain barrel (optional)
• Rocks
• A variety of plants
  • Native grasses, reeds and plants are well suited to local growing conditions, resist soil erosion, and can be moisture- and drought-tolerant

What's involved

Contact your local government to see if there are local codes, regulations, permits and inspections required before installation.

Rain gardens

• Choose a low-lying, flat area in your yard where you notice that water pools from rain, ice melt and snowmelt
  • The location should be at least three metres (about 10 ft.) away from your home or other nearby properties and at least 4 metres (about 13 ft.) away from a septic bed
• Safely dig a hole that is at least 85 cm (2.7 ft.) deep
  • Ensure you know where gas pipes or other underground obstacles are located before you start digging
  • Contact your local utility provider to find out how to request a utility locate service
• Fill the hole with a rain garden soil mix that allows for water infiltration, such as a sand or compost mixture
• Select plant species with deep and water-tolerant root systems
• Ensure your garden directs excess water away from your home
  • Direct downspouts and rain barrel overflow pipes towards the garden
  • Dig a channel for the water to overflow from the garden as needed
• Place rocks where water enters and exits the rain garden to:
  • slow the flow
  • reduce soil erosion

Rocks and rock gardens

• Rocks and rock gardens generally require little maintenance
• Create a channel of rocks from your downspout to the rain garden to:
  • direct the flow of water away from your home
  • improve drainage
  • reduce soil erosion
• Use larger rocks to create the walls of the channel, and place smaller stones, such as river rocks inside the channel
• Some waterfront properties use rocks to create retaining walls, which provide a barrier against floodwaters
  • This is useful for those at risk of coastal flooding
  • Consult a professional about installation and to discuss proper drainage systems for retaining walls
  • Be mindful that saturated or eroded soil behind the wall can fail over time

Permeable pavement

• Permeable pavement installation typically involves professional assistance
• Consult with your local government for regulations, building codes or permits required to take this action
• Ideal for patios, walkways or driveways to increase your home's flood resilience
• Permeable pavement does not replace drains and should be properly graded
  • If installed on a reverse slope driveway, run a trench drain across the driveway to avoid flooding the home or garage

Cost

Costs may vary across Canada.

Rain gardens

• Rain gardens can range from $300 to several thousands of dollars
  • Costs depend on the size and style of your rain garden, the existing condition of your yard, and if you hire a professional
• Rebates, grants, loans, or subsidies may be available based on:
  • the number of litres of water your rain garden captures
  • the cost of installation
• Check with your local government to see if these programs are available in your region

Rocks and rock gardens

• Costs can range from $250 to several thousands of dollars
  • Costs depend on the material, size and amount of the rocks selected
  • Landscaping rock is typically sold by weight or cubic yard

Permeable pavement

• Permeable pavement can range from $10 to $15 per square foot
• Check with your local government to see if rebates, grants, loans, or subsidies are available in your region

When to do it

Rain garden

• Install in spring, summer or fall – anytime the ground is not frozen
• Minimal maintenance is required after installation
  • Water your garden often during the first two years and during dry periods
  • Weeding and fertilizing aren't required for flood reduction reasons
• Check for soil erosion to ensure your plants are healthy:
  • Signs of soil displacement such as exposed roots, gullies or sediment accumulation
  • Look for soil erosion such as undercutting or areas where the soil has washed out
• Monitor plant growth
  • Look for bare spots or plant decline
  • Replenish plants to maintain plant density and enhance soil retention

Rocks and rock gardens

• Set up anytime the ground is not frozen
• Minimal maintenance is required afterwards
• Monitor for rocks that have shifted out of place
• Low-growing plants, ground covers and mosses may grow between the rocks and do not need to be removed for flood reduction reasons

Permeable pavement

• Sweep often in the spring and fall to make sure the gaps in the pavement, which allow water to infiltrate, are unobstructed
• Inspect your pavement for any cracks, holes or other signs of damage
• Repair small cracks and holes by:
  • Cleaning the affected area of debris
  • Fill with appropriate patching materials recommended by pavement manufacturer
• Consult a professional to repair significant damage

Combine tasks for efficiency

Flood-wise landscaping should be considered when you are grading your property. This pairing will minimize disruptions and maximize flood ready improvements to your home.

Be flood ready

Flood readiness requires regular upkeep just like any other home or property task. Make maintaining and improving your flood-wise landscaping part of your seasonal maintenance checklist.

Seek support from a local professional, friend, family or community member, if you're unable to complete this task on your own.