If your lawn looks thin after summer heat and foot traffic, overseeding is the fastest, most cost-effective way to bring it back. In Calgary’s cool-season climate, pairing overseeding with dethatching and core aeration gives new seed the best shot at life—and the right Kentucky bluegrass (KBG) / fine fescue blend keeps it resilient through chinooks, drought spells, and cold snaps.
Below is our Calgary-specific playbook. Please see When to Aerate Your Lawn in Calgary? Time for a Green Yard! for More info or Free Estimate to book now!
Why Overseed At All?
Overseeding adds fresh, vigorous grass plants into a tired lawn, improving density, colour, and weed resistance. The ideal window for cool-season turf (like KBG and fescues) is late summer to early fall—soil is warm, air is cooler, and weed pressure is lower, which helps germination and root establishment before winter.
Timing for Calgary (late August–mid/late September)
Northern, continental cities recommend a mid-August to mid/late-September seeding window for cool-season grasses . That aligns perfectly with Calgary’s conditions: warm soil + cool nights = faster germination and fewer weeds. Aim to seed at least 4 weeks before the first hard frost so seedlings can establish .
The City of Calgary notes KBG is slow to establish, making the timing even more critical .
Preparation: dethatch → aerate → seed
- Dethatching
Thick thatch blocks seed-to-soil contact and water. Removing thatch opens the surface so seed can touch soil and roots can breathe. Thatch tends to build faster in KBG and fine fescue lawns . - Core aeration
Aeration relieves compaction and creates seed “pockets” where moisture and oxygen reach roots. City of Calgary guidance recommends hollow-tine aeration on moist soil, leaving plugs to decompose . For cool-season grasses, aerate during cool weather (spring or late summer/early fall) . - Seed application
Spread seed evenly in two directions for uniform coverage; rake lightly so 10–15% of seed remains visible. Roll or press for firm seed-to-soil contact .
The right seed for Calgary: KBG + fine fescue blend
- The City of Calgary recommends a fescue-heavy mix (≥60% fescue) with ≤20% Kentucky bluegrass for residential lawns .
- KBG adds density and self-repair via rhizomes but establishes slowly and may go dormant in drought. Fine fescues (like creeping red) handle shade and drought better .
- Mixing species improves performance—KBG provides recuperative ability while fescue boosts drought tolerance .
- Local sod farms also use KBG/fescue blends tailored to Southern Alberta .
How much seed? (Calgary-friendly overseeding rates)
University extension guidelines suggest:
- KBG: ~1.5 lbs/1,000 sq ft
- Fine fescues: ~2.5 lbs/1,000 sq ft
- Tall fescue (if applicable): ~4 lbs/1,000 sq ft .
Watering & first mow
- Water lightly and frequently to keep the top 1–2 cm of soil damp until germination, then shift to deeper, less frequent watering .
- First mow when new grass hits ~7.5 cm (3 in.) with a sharp blade .
FAQ
Is spring overseeding okay?
Yes—spring can work, but expect more weeds and slower establishment .
How often should I overseed?
Every 2–3 years is typical; annually if traffic or drought damage is high .
Will a KBG/fescue mix handle drought?
Fine fescues generally survive drought equal to or better than KBG, while KBG usually recovers thanks to rhizomes .
Sources
City of Calgary – Seeding (lawn overseeding & seed guidance)
https://www.calgary.ca/property-owners/lawn-seeding.html https://www.calgary.ca
City of Calgary – Lawn Care (including aeration & dethatching)
https://www.calgary.ca/water/programs/lawn-care.html https://www.calgary.ca
City of Calgary – Homeowner Water Guide: Lawn Care (PDF)
https://www.calgary.ca/content/dam/www/uep/water/documents/water-documents/homeowner-water-guides/lawn-care-guide.pdf https://www.calgary.ca
University of Minnesota Extension – Seeding and Sodding Home Lawns
https://extension.umn.edu/lawn-care/seeding-and-sodding-home-lawns University of Minnesota Extension
University of Minnesota Extension – Planting and Maintaining a Fine Fescue Lawn
https://extension.umn.edu/lawns-and-landscapes/planting-and-maintaining-fine-fescue-lawn University of Minnesota Extension
University of Minnesota Extension – Dormant Seeding Your Lawn
https://extension.umn.edu/lawn-care/dormant-seeding University of Minnesota Extension
Better Homes & Gardens – How Often to Overseed Lawn
https://www.bhg.com/how-often-to-overseed-lawn-11789839 bhg.com
