Tips and advice
A boulevard garden can greatly enhance your neighbourhood with colourful, fragrant plants. Boulevard gardens add interest and texture to an otherwise uninspiring part of your property.The boulevard on either side of your sidewalk is owned by the City of Guelph and an Encroachment By-law is in place to ensure the space is used for its intended purpose. The City may need to repair or upgrade utilities that are under your boulevard or sidewalk at any time. Any resulting damage will not be repaired by the City. Gardeners are responsible to know and follow the ordinances that pertain to boulevard plantings.
The City of Guelph’s Encroachment By-law states that plants cannot be higher than 0.8 m or 2.5 ft. This is meant to maximize visibility for pedestrians, cyclists and motorist. Try to keep taller plants toward the center of your boulevard. Don’t allow your plants to droop onto sidewalks, curbs, or alleys. Stake taller plants if they tend to droop (tip: open a metal clothes hanger and push the two ends into the ground around the plant to stake it up.) Watch out for sightlines, especially if you are on a corner lot. Make sure your plants to not block sightlines for vehicles or access for pedestrians.
Structures, containers, rocks and pavers
Keep in mind that other people may need to use your boulevard before adding any obstructions. Rocks and pavers must be below the grade of the sidewalk and curb so that they don’t interfere with road or sidewalk maintenance.
There may already be a tree on your boulevard. It’s essential that you consider tree health when planning your boulevard garden. Boulevard trees already face harsh growing conditions. When planting around trees:
- Do not dig or damage the roots of the tree. Measure the diameter of your tree trunk at 1.4 m (4.5 ft) above the ground. Multiply this number by 0.5 m (1.5 ft). The result is the distance in which major tree roots extend in all directions from the trunk.
- The majority of tree roots grow within the top 15 cm (6 in.) of soil. You may have to leave a border of grass around the tree, or remove the top layer of grass.
- Do not place more than 10 cm (4 in.) of soil or compost directly above tree roots. Excessive mulch retains surface water which promotes shallow rooting of trees. Deep rooted trees will survive drought stress more readily and are less susceptible to wind damage.
- Water your tree deeply. In dry periods your boulevard tree needs 5 cm of water per week. Avoid frequent, shallow watering which may lead to weak, shallow tree roots.
- Do not nail or tie signs, trellises or other fixtures to any tree.
Driveways and sidewalks
Always keep in mind that cars will park next to your boulevard and that passengers will use your boulevard. Try to leave an edge of turf or walkable groundcover on the street side.
Soil erosion caused by mounded boulevard gardens can be an erosion problem. Use shredded hardwood mulch around plants, keeping the final mulched surface 2.5 cm below the curb or sidewalk. Allow a shallow 2.5 to 3.5 cm depression in the centre of the garden to help catch rainwater and prevent soil/mulch erosion. Each garden is unique, but try to remedy the site if mounding and erosion is an issue.
An ideal time to prepare your boulevard garden is in the spring or fall. Don’t dig up the grass. Soil
disturbance tends to encourage weed growth. The sheet mulching method is recommended.
Boulevards are exposed to hot sun, wind, snow, salt, car exhaust and foot traffic. Soil conditions may be dry and compacted. Many plants will thrive in these conditions. Avoid rare, expensive, exotic or plants that need special care.
Sheet mulching method
- Dig out existing weeds, as they may grow through the newspaper.
- Dig a shallow trough a few inches around the edge of the planting area to provide a buffer zone.
- Mow the grass very short, leave clippings.
- Spread a layer of compost.
- Wet newspapers in a wheelbarrow filled with water, and then lay them on top of the grass about four to ten sheets thick. Make sure the papers overlap each other so that no light gets through.
- Spread a few inches of mulch (wood chips, leaves, straw or compost) on top of the newspaper.
- You can leave the area for the winter for the grass to break down underneath the newspaper layer, or you can plant right away.
- When planting, push away some mulch, cut a hole in the newspaper layers and plant.
Plants for a boulevard garden
Salt tolerant perennials
Artemisea (Silvermound) – Artemisia schmiditiana
Blue Fescue Grass – Festuca glauca
Blue Lyme Grass – Elymus arenarius
Dianthus – Pulmonarius x allwoodii
Plaintain Lily (Hosta) – Hosta spp.
Sea Lavender – Limomium latifolium
Sea Thrift – Armeria maritima
Drought tolerant perennials
Butterflyweed – Asclepias tuberosa
Carpet Bugle – Ajuga reptans ‘Palisander’
Snow-in-Summer – Cerastium tomentosum
Common sage – Salvia officinalis
Creeping Chamomile – Chamaemelum nobile
Feverfew ‘Golden Ball’ – Tanacetum parthenium
Lambs ear – Stachys byzantine
Lavander – Lavandula spp.
Ornamental Grasses – species vary
Pearly Everlasting – Anaphalis
Pussy toes – Antennaria dioica
Sedum – Sedum spp.
Silver Brocade – Artemisia stelleriana
Spurge – Euphorbia spp.
Threadleaf Coreopsis – Coreopsis verticillata
Thyme – Thymus spp.
Yarrow ‘Moonshine’ – Achillea
Low spreading evergreens
Blue Rug Juniper – Juniperus
Dwarf Canadian Hemlock – Tsuga
Canadensis ‘Cole’s Prostrata’
Golden Japanese Yew – Taxus
Japanese Garden Juniper – Juniperus procumbens ‘Nana’
Rug Juniper – Juniperus horizontalis
‘Prince of Wales’
Siberian Carpet Cypress – Microbiota decussate
Star Juniper – Juniperus squamata
Perennials for shade
Bergenia – Bergenia cordifolia
Bethlehem Sage – Pulmonaria saccharata
Blue Lungwort – Pulmonaria angustifolia
Common Bugle – Ajuga reptans
Deadnettle – Lamium maculatum
English Ivy – Hedera Helix
Euonymus – Euonymus fortunei ‘Coloratus’
Goat’s Beard – Aruncus dioicus
Japanese Spurge – Pachysandra terminalis
Periwinkle – Vinca minor
Sweet Woodruff – Galium odoratum
Wintergreen – Gaultheria procumbens
Christmas Fern – Polystichum acrostichoides
Hayscented Fern – Dennstaeditia punctilobula
Lady Fern – Athyrium filix femina
Maidenhair Fern – Adiantum pedatum
Ground cover that is too invasive for a garden work well in a confined boulevard setting. Avoid aggressive exotics that pose problems for many natural ecosystems, where their seeds are distributed into the wild. Try to avoid goutweed (snow-on-the-mountain), ribbon grass, bindweed, lemon balm and creeping bellflower.