"Working with James was great from the beginning. He put my mind at ease with his product knowledge and his creative designs."
Softscape & Gardens · Mississauga, GTA
Garden & Landscape Design in Mississauga.
Astonia Landscaping brings owner-led landscape design and natural-stone masonry to Mississauga. James Dennison, a third-generation stonemason, has built grounds for discerning homeowners across the Greater Toronto Area since 1975 — and the western edge of the GTA, with its established estate streets and its newer luxury builds, is squarely the kind of work we take on.
- Since 1975
- 3 Generations
- $5M Insured
- WSIB Covered
- Unilock Authorized
In Mississauga
Landscaping that belongs in Mississauga.
Mississauga is two cities at once, and the difference shapes the work. South of the QEW, enclaves like Lorne Park, Mineola and the stretch along Mississauga Road hold some of Peel's oldest estate lots — deep, generously treed parcels where mature oaks and a settled grade are part of what the property is worth. North and west, the luxury builds are newer and larger, often on cleared ground that has yet to grow into itself. We approach the two differently: one asks for restraint and protection of what is already there, the other for design that gives a young property weight and a sense of permanence from the start.
Homeowners in these neighbourhoods tend to be making a once-in-a-generation investment, and they care about how the work is carried out as much as the result. Owning our own small and heavy equipment means we move on our own schedule rather than waiting on subcontractors, which matters on the narrow, established frontages off Mississauga Road where a job can sit exposed to the street. We haul every load of debris away in our own trucks — no bins parked on the boulevard for weeks — and our crews are WSIB-covered and backed by $5M in liability insurance, which is the baseline these homeowners expect.
The mature estate lots reward careful reading of the site. Old trees with protected root zones, long-settled grades, and the drainage that comes with a deep, sloping property all have to be respected before the first stone is set, and natural stone laid for these grounds should look as though it has always belonged. As a Unilock Authorized Contractor, we also work in engineered hardscape where a newer build calls for it. Either way, the priority is the same — a landscape that suits the house and the street and holds up for decades.
What we build
Garden & Landscape Design, start to finish.
Garden Design
Planting Plans
Mature Trees & Shrubs
Lawns & Sod
Grading & Drainage
Seasonal Colour
The craft
Built from the ground down.
A garden is the part of a landscape that keeps changing after we leave. The stonework holds its line for fifty years; the planting is alive, and the difference between a good one and a forgettable one is whether it was designed to grow into its setting. We start with the site as it actually is — how the sun tracks across it through the day, where water collects after a storm, what the soil is made of once you dig past the first spade. From that we draw a planting plan: the structure of mature trees and evergreens first, then the layers of shrubs, grasses and perennials that fill in beneath them, chosen for this neighbourhood's climate and this property's light. It is a composition meant to read well in its first season and far better in its tenth.
Healthy planting begins below grade, which is why grading and drainage come before anything goes in the ground. We shape the land so water moves away from the house and the beds rather than pooling against them, correcting the slow problems — soggy lawns, drowned roots, the low corner that never dries — that no amount of replanting will fix on its own. Then we build the soil. We strip out the spent, compacted fill that builders leave behind and bring in screened topsoil and compost matched to what we're planting, so roots have somewhere to go. Beds are edged cleanly and finished with mulch that holds moisture, suppresses weeds and breaks down into the soil over time. None of this shows in a photograph, and all of it is the reason a garden still looks intentional years later.
We plant at a scale that suits the homes we work on. Mature trees and specimen shrubs are sourced, moved and set with our own equipment, so a new garden arrives with weight and presence rather than waiting a decade to earn it — and because we own that equipment and run our own crews, large stock is placed without the delays and damage that come from subcontracting the heavy work. Lawns are established properly, with the grading, soil and seed or sod chosen for how the space will be used and how much sun it gets. When everything is in, we haul every pallet, root ball and offcut away in our own trucks. There are no bins left sitting on the driveway and no debris waiting on someone else's schedule.
Through it all you deal with James and his crew directly, the same people who designed the garden and will be standing in it as it goes in. We think about how the planting carries across the year — early bulbs, the long middle of summer perennials and grasses, the structure and colour that hold through autumn and into winter — so the garden has something to offer in every season rather than peaking once and going quiet. Astonia has been building landscapes across the GTA and Durham Region since 1975, work that is fully insured to five million dollars and carried out by WSIB-covered crews. For homeowners making a once-in-a-generation investment in their property, that combination of craft, restraint and accountability is the whole point.
How it works
From first handshake to final reveal.
01
Initial Consultation
We meet you on-site to walk the space, understand how you want to live in it, and talk through your vision and investment — no obligation.
02
Design & 3D Review
Our designer measures and plans your space, then renders it in 3D so you can see it before we break ground. We refine every detail together.
03
Breaking Ground
Our own crews and equipment start at 7:00 AM, keep the site clean every day, and brief you each morning and evening — no subcontractor gaps, no bins.
04
Project Completion
After a final walkthrough, the only thing left behind is your finished space — built to gather on for generations.
The Astonia difference
Why homeowners in Mississauga choose us.
Owner-led
Daily communication from James, from the first handshake to the final reveal.
Our own equipment
Small and heavy machines, run by our own crews — no subcontractor delays.
No unsightly bins
We haul every bit of debris away in our own trucks, every day.
$5M insured
Liability coverage above the industry average, for your peace of mind.
WSIB covered
A fully covered, professional crew on every project.
Unilock Authorized
Warranty-grade materials and professional installation standards.
Kind Words
Homeowners across the GTA, on the Astonia experience.
Five decades of referrals across the GTA & Durham — and a Unilock Authorized Contractor. Read more on Google & Houzz.
"The natural stone work and landscape job that James and his crew did is beautiful, outstanding work. The quality is outstanding — we would recommend this company to anyone."
"Astonia was a delight from start to finish. The crew showed up early and worked long days to finish on time. We are now enjoying the most amazing front yard. Outstanding results!"
"As a repeat client, we selected Astonia to transform our simple backyard into a relaxing space amongst a natural setting that will bring us many years of pleasure."
Good to know
Garden & Landscape Design in Mississauga, answered.
We plant at full scale. Specimen trees and mature shrubs are sourced, moved and set with our own equipment, so the garden arrives with real presence in its first season instead of waiting years to fill in. Because we own the machinery and run our own crews, large stock is placed without the delays or handling damage that come from subcontracting the heavy lifting.
Both, and the order matters. We grade the land so water drains away from the house and the beds, correct low spots and poor runoff, then rebuild the soil with screened topsoil and compost before anything is planted. A garden built on neglected grading and spent builder's fill will struggle no matter what goes in the ground, so we do that groundwork first.
We design and build across the GTA & Durham region — including Toronto, Etobicoke, Mississauga, Brampton, Oakville, Vaughan, Markham, Newmarket, Aurora, King City, Whitby, Oshawa, Bowmanville and the surrounding areas.
Every project is different — from focused stonework to a full landscape transformation — so we provide a clear, detailed proposal after an on-site consultation rather than a generic price. Most of our work is a meaningful, lasting investment in your property.
Timelines depend on scope, and you receive a realistic one at the design-review stage before we break ground. Because we own our equipment and run our own crews, we work efficiently — starting at 7:00 AM and keeping the site clean every day.
Yes. We carry $5 million in liability insurance — above the industry average — our crews are fully WSIB covered, and we are a Unilock Authorized Contractor.
More services in Mississauga
Garden & Landscape Design nearby
Garden & Landscape Design in Mississauga, done right.
Book a free on-site consultation. We design, build and plant the whole space — then haul it all away when the last stone is set.
$5M insured · WSIB-covered crews · 3rd-generation craftsmanship since 1975