Most disappointing garden beds are not badly planted. They are badly sized and under-planted. A 30 inch strip along the fence cannot hold a layered border no matter what goes in it, and twelve plants scattered across 200 square feet will look sparse for five years. This guide covers how we lay out and plant beds across Hamilton, Burlington and Oakville, including the arithmetic that tells you how many plants to buy.
Start with the size of the bed, not the plants
| Bed depth (front to back) | What it can hold | Use it for |
|---|---|---|
| Under 3 ft | One row of one plant type | A ribbon along a walkway or foundation. Accept that it is a line, not a border. |
| 3 - 4 ft | Two layers | A low front bed, a bed against a fence with shrubs behind a perennial row. |
| 5 - 8 ft | Three layers, plus a small tree | A real border. This is where beds start to look like the photos. |
| 8 ft+ | Layers plus a path or stepping stones | Large back borders and island beds. Add stones so you can reach the back to weed. |
A bed also needs to be in proportion to what it sits against. A foundation bed along a two-storey wall looks mean at 3 feet and right at 5 or 6. When in doubt, lay a garden hose on the lawn in the shape you are considering, go inside, and look at it from the window you use most. If it looks too big from there, it is about right on the ground.
The plant count formula
This is the number nobody gives you at the garden centre. Plants needed equals the area of the bed in square feet, divided by the spacing in feet squared.
| Spacing | Area per plant | Plants per 100 sqft | Typical plants |
|---|---|---|---|
| 12 in | 1.0 sqft | 100 | Groundcovers, creeping sedum, sweet woodruff |
| 15 in | 1.6 sqft | 64 | Heuchera, hosta (small), catmint |
| 18 in | 2.3 sqft | 44 | Most perennials: salvia, coneflower, daylily |
| 24 in | 4.0 sqft | 25 | Large perennials, small grasses, peony |
| 30 in | 6.3 sqft | 16 | Switchgrass, Russian sage, large hosta |
| 36 in | 9.0 sqft | 11 | Small shrubs: spirea, dwarf hydrangea, boxwood |
| 48 - 60 in | 16 - 25 sqft | 4 - 6 | Hydrangea paniculata, viburnum, serviceberry |
Space to the mature width on the tag, not to the pot. A 4 inch heuchera that wants 15 inches gets 15 inches, and the bed looks thin for one season and full for the next twenty. If you cannot stand a thin first year, fill the gaps with annuals rather than crowding the perennials.
Layers, and what goes where
- Back layer (structure). Shrubs and small trees that hold the bed together in February: serviceberry, viburnum, panicle hydrangea, dwarf spruce, ninebark. Roughly a third of the bed.
- Middle layer (the workhorses). Knee to waist-high perennials and grasses that carry the flowering: coneflower, daylily, salvia, rudbeckia, phlox, switchgrass.
- Front layer (the edge). Low, tidy plants that hide the bare legs of the middle layer and meet the lawn or path: catmint, heuchera, sedum, hardy geranium, lady's mantle.
- The edge itself. A clean line matters as much as the plants. Our garden edging guide compares steel, stone, paver and spade-cut edges and what each costs.
Keeping something in flower, April to October
A bed that peaks for two weeks in June and then sulks is the most common planting failure in Ontario. Pick at least two things from each row below and the bed carries the whole season.
| Window | Carried by |
|---|---|
| April to early May | Daffodil, scilla, hellebore, creeping phlox, serviceberry blossom, Virginia bluebells |
| Mid May to June | Peony, Siberian iris, catmint, baptisia, salvia, weigela, hardy geranium |
| July | Daylily, coneflower, bee balm, yarrow, panicle hydrangea starting |
| August | Rudbeckia, garden phlox, Russian sage, liatris, hydrangea in full colour |
| September to October | Aster, sedum turning russet, Japanese anemone, ornamental grasses in seed |
| November to March | Evergreen structure, grasses left standing, red twig dogwood, seed heads under snow |
That last row is the one people skip. Leave the grasses and the sedum heads standing over winter instead of cutting everything to the ground in October: they hold snow, feed birds and give you something to look at for five months. For named plant picks by condition, see our guides to the best perennials for Ontario gardens and shade plants for Ontario.
Garden bed design ideas
1. The layered fence-line border
The most useful bed in most Ontario backyards. Take the strip along the back fence out to 5 or 6 feet, put shrubs at the back to soften the fence, perennials in the middle and a tidy front edge. It hides the fence, gives you depth to look into, and turns a rectangle of lawn into a room.
2. The island bed
A free-standing bed in the lawn, tallest in the middle, viewed from all sides. It breaks up an open yard and shortens the mowing. Keep the shape simple: long curves that a mower can follow, no tight wiggles.
3. The foundation bed done properly
Not five meatball shrubs in a row. Pull the bed out to at least 4 feet, keep anything tall away from windows, leave 18 inches between the mature shrub and the wall for air and access, and repeat a small group of plants along the front of the house so the two sides of the door speak to each other.
4. The all-season low-care bed
Massed planting of a few tough species, planted tight so they close over and shade out weeds: catmint, little bluestem, sedum, coneflower and a repeated dwarf shrub. It is the planting that needs least of your time. More on this approach in our low maintenance backyard ideas.
5. The cutting and pollinator bed
Native and near-native plants that feed pollinators and give you flowers to cut: bee balm, coneflower, liatris, aster, anise hyssop, black-eyed Susan. Most are clay tolerant and drought tolerant once established.
6. The shade bed under a maple
Dry shade under a mature Norway maple is the hardest spot in an Ontario yard. Do not till, because you will wreck the roots. Build up 3 to 4 inches of compost and plant small: hosta, epimedium, brunnera, wild ginger, sedge and ferns.
7. The narrow side-yard bed
A 3 ft strip between the house and the property line. Use upright, narrow plants, repeat a single species for calm, and put a path down the middle rather than trying to grow grass that never sees sun.
8. The mixed bed with a raised box in it
Ornamental planting around a cedar raised bed of herbs and cut flowers. It puts the edible garden where you will look at it instead of behind the shed. Our raised garden bed guide covers sizes and soil.
Preparing a bed in clay, which is most of this area
Hamilton, Burlington and much of Halton sit on heavy clay. The two rules that matter:
- Amend the whole bed, not the planting hole. A hole of nice soil in clay behaves like a bucket: water runs in, cannot get out, and roots drown. Work 4 to 6 inches of compost into the top 8 to 12 inches of the whole bed.
- Or lift the bed. Raising the planting surface 20 cm or more above the clay sidesteps the problem entirely, which is why so many beds here are built up behind a low wall or a steel edge.
Our guide to planting in Ontario clay soil goes into the detail, and if water sits in the yard for more than a day after rain, fix that before you plant anything: see why water pools in a backyard.
Finishing and first-year care
- Mulch 2 to 3 inches deep, pulled back from stems and trunks. Not more, and never a volcano against a trunk. See when to mulch garden beds in Ontario.
- Water deeply once or twice a week in the first season rather than a little every day. New perennials need one full growing season to root; shrubs need two.
- Do not fertilize a new bed that has been amended with compost. You are feeding weeds.
- Edit in year two. Something will be in the wrong place. Perennials move easily in spring or early fall.
What a designed bed costs
A planted and mulched garden bed runs about $19 to $46 per square foot installed in 2026, which covers soil preparation, plants, mulch and labour. A 5 x 20 ft border is therefore roughly $1,900 to $4,600 depending on plant sizes and how much soil work it needs. Buying small and waiting saves real money: a 1 gallon perennial catches a 2 gallon one within two seasons. If you want a plan drawn before anything is planted, see our landscape design cost guide.
Frequently asked questions
How do I design a flower garden from scratch?
Set the bed shape and depth first with a hose on the lawn, aim for at least 4 feet deep, then choose about five plant types, work out numbers with the spacing formula, and check that something flowers in every month from April to October.
How many plants do I need for my garden bed?
Divide the bed area in square feet by the square of the spacing in feet. At 18 inch spacing that is about 44 plants per 100 square feet; at 24 inches it is 25.
How deep should a garden bed be?
At least 4 feet front to back for two layers of planting, and 5 to 8 feet if you want a proper three-layer border. Under 3 feet you can only really grow a single row.
What should I plant at the front of a border?
Low, tidy plants that hold a clean line: catmint, heuchera, low sedum, hardy geranium, lady's mantle or a clipped dwarf shrub repeated along the edge.
How much does a new garden bed cost in Ontario?
About $19 to $46 per square foot installed in 2026, including soil preparation, plants, mulch and labour. A 5 by 20 foot border is roughly $1,900 to $4,600.
Should I use landscape fabric under a garden bed?
No. Fabric under a planted bed stops you dividing and adding plants, and weeds root in the mulch on top of it anyway. Use fabric only under stone.
When is the best time to plant a new bed in Ontario?
Spring from late April to early June, or late August to early October. Both avoid planting into midsummer heat, and fall planting lets roots settle before winter.