Chicago, IL / Kentucky Bluegrass Turf

Total GDD: 4045 (Nov 15)

Day 246 / 246 (100%)

Total GDD: 4045 (Nov 15)

Method: 50°F

7-Day Daily Avg: 3.4

7-Day Projection: 4069 by Nov 22

Season: Mar 15, 25 - Nov 15, 2025

Last Freeze:
10%: 03-28
50%: 04-10
90%: 04-18

First Freeze:
10%: 10-11
50%: 11-01
90%: 11-13

Growing Degree Days (GDD) track heat accumulation to predict when plants reach growth stages, pests emerge, and diseases become active.

Thresholds mark specific GDD values when events typically occur, with crossing dates showing when your season reaches each milestone.

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PGR Program Start 200 °D

Apr 24, 2025 | Apr 27, 2024 | Apr 19, 2023

Growth Stage

Spring green-up complete. Begin Primo Maxx at 200 GDD intervals. Seedhead suppression timing.

Spring Peak 500 °D

May 22, 2025 | May 18, 2024 | May 21, 2023

Growth Stage

Maximum spring growth. Tighten intervals to 10-14 days. Scout for billbug adults on sidewalks.

Summer Stress 1500 °D

Jul 5, 2025 | Jun 29, 2024 | Jul 7, 2023

Growth Stage

Growth slows in heat. Extend intervals or pause PGR. Prioritize irrigation over regulation.

Fall Recovery 3000 °D

Aug 30, 2025 | Aug 27, 2024 | Sep 5, 2023

Growth Stage

Second growth flush. Resume tight intervals. Prime overseeding and renovation window.

PGR Program End 3500 °D

Sep 24, 2025 | Sep 18, 2024 | Oct 3, 2023

Growth Stage

Discontinue applications. Allow hardening before winter dormancy.