Fall Landscape Prep in Northern Colorado: A Week-by-Week Guide

The September–October Window Is Irreplaceable

No other time of year has the confluence of conditions that makes fall the best maintenance and investment period for Northern Colorado landscapes. Cool air, warm soil, diminishing weed pressure, and adequate moisture combine to make September and October the months that matter most.

Labor Day Week — Aeration and Overseeding

If you're going to aerate and overseed, this is the target window. Soil temperatures are still warm enough for germination (55°F+), air temperatures are cooling, and you have 6–8 weeks before first frost.

Week of Labor Day:

• Core aerate entire lawn (double pass for compacted soil)
• Overseed at appropriate rate for your grass type
• Apply starter fertilizer
• Begin germination watering schedule (2–3x daily, light cycles, for 14 days)

Mid-September — Tree and Shrub Care

• Deep root water all trees and shrubs if September is dry (it often is)
• Apply anti-desiccant spray to broadleaf evergreens (boxwood, holly)
• Complete any structural pruning on trees before leaves drop
• Plant spring-blooming bulbs (tulips, daffodils, alliums) — they need cold stratification over winter

Late September — Irrigation Timing Decision

First average frost in the Northern Colorado Front Range is typically October 5–15, varying by year and elevation. Plan irrigation winterization for early October in most years. Book now — contractors fill up quickly.

First Two Weeks of October — Winterization Window

✓ Irrigation winterization (before first hard freeze)

✓ Winterizer fertilizer — apply to established turf in early October

✓ Leaf management — first heavy leaf fall begins, especially under cottonwoods

Pro Tip: You don't have to remove every leaf immediately. A light leaf cover doesn't hurt turf. The problem is thick, matted leaves left under snow for weeks. Aim for removal by late October before the first significant snowfall.

Late October — Wind-Down Tasks

• Final mow at 2.5–3 inches
• Drain and store hoses
• Cut back ornamental grasses (or leave for winter interest — both are acceptable)
• Apply fresh mulch to beds if not done in spring — insulates root zones for winter

Updated on: 29/04/2026