Starting every crop on one weekend
Warm crops, herbs, and cool-season crops need different lead times.
Timing Tool · 2 min
Seed Starting Calculator
Turn one frost date into a crop schedule you can put on a calendar today.
Pick a crop and last frost date to get indoor sowing, hardening-off, and transplant windows.
What this tool decides
Decides practical indoor sowing, harden-off, transplant, and direct-sow dates from one frost date.
- 1Set your inputs
- 2Calculate the number
- 3Read the plan
Seed Starting
Change any field and the result updates immediately.
Calculated resultEnter your measurements
The practical plan will appear here.
Read the Plan
How to use this result
What it means
The result counts backward from an estimated transplant date. Indoor lead times follow the extension ranges linked below; the selected frost offsets still need local adjustment.
Next action
Put the dates on your calendar, then check spacing so the number of starts matches the bed.
Check these before using the number
Skipping hardening off
Indoor seedlings need a gradual transition to sun, wind, and outdoor temperatures.
Timing sources and limits
These extension guides support indoor growing and hardening intervals. The frost offsets are editable examples, not dates prescribed by those sources. Direct sowing tomatoes or peppers may leave too little time to harvest in a short season.
Work backward from transplant timing
Start with the outdoor planting window and count backward. The indoor sowing date follows from the crop rather than convenience.
The frost offsets are editable planning assumptions, not regional planting recommendations. A USDA zone cannot supply a frost date or soil temperature.