Nobody forgets to fertilize their lawn. What people forget is when they did it. And that is where most lawn problems start: a second spring feeding three weeks after the first, a fall application that never happened because someone assumed it did, or a mowing height that crept down all summer.
What should you track?
The date and the task, every time, plus the details you will need for the next decision:
| Task | What to log | What you use it for |
|---|---|---|
| Fertilizer | Product, N-P-K, pounds spread | When the next feeding is due, how much nitrogen went down |
| Mowing | Cutting height | Spotting whether you cut too short during heat or drought |
| Dethatching | Tines or fixed blades | How hard the lawn was worked and when it can take it again |
| Seeding | Seed type, rate, overseed or new lawn | Which blend actually filled in |
| Lime and pH | Soil test result, pounds of lime | Whether the pH is moving the right way |
| Iron | Product and rate | Keeping iron separate from nitrogen when judging color |
The fertilizer line matters most. Six to eight weeks between applications is standard, and three weeks is the absolute minimum. If your log says May 25, you know the lawn is due in early fall, not in July.
What a lawn care log looks like in the app
Here is the log for the example lawn in Chicago: a mow at 3 inches and 14 lb of lawn food on May 25.
To add an entry you pick the task at the top: mow, fertilizer, lime, pH, seeding, scarify (dethatch), aerate, seaweed, wetting agent, iron sulphate and ground temp. For mowing you set the cutting height on a scale that shows how much blade you leave.
What does the app do with your log?
A notebook only helps if you go back and read it. In the app the log feeds straight into the advice:
- Weeks since the last feeding shows on the Fertilizer Score, like “16w ago”. Under three weeks, the app says don’t apply, no matter how good the weather is.
- Recent activity shows on the dashboard, so the last few jobs are visible at a glance.
- Money spent adds up the cost from every entry where you filled it in.
- pH over time is drawn as a graph, so you can see whether lime or sulfur is working.
That means on a Saturday in September you can open the app and see whether the lawn is due for its fall feeding, instead of digging for a receipt from May.
What can you learn from a season of logs?
After a year, patterns show up that are hard to see from week to week:
- The lawn went brown in the July you mowed at 2 inches, and stayed green the next year at 3.
- Spring overseeding barely came up, while the Labor Day seeding filled in within a month.
- The March fertilizer did nothing visible, and the one in late April did. Soil temperature, not the calendar, was the difference.
That last one is the most common. When soil is warm enough and when to hold off is covered in When to Fertilize Your Lawn.
What a Green Lawn has the lawn log built in and combines it with your local forecast to tell you when the next job is worth doing.