Window Schedule Calculator for Gardens

Example data table

Formula used

This calculator builds planting windows using simple date offsets from your frost dates. For each crop, you provide spring and fall offsets in days.

• Spring Plant Start = Last Frost Date + Spring Start Offset
• Spring Plant End = Last Frost Date + Spring End Offset
• Fall Plant Start = First Frost Date + Fall Start Offset
• Fall Plant End = First Frost Date + Fall End Offset
• Harvest Start Range = Plant Start + DTM
• Harvest End Range = Plant End + DTM + Harvest Span
• Latest Safe Fall Planting ≈ (First Frost Date − Buffer) − DTM

Buffer days reduces frost risk by shifting the safe window inward. Status becomes Caution when the fall window extends beyond the latest safe planting date.

How to use this calculator

1. Enter your last and first frost dates for your garden.
2. Choose buffer days based on exposure and elevation.
3. Add one row per crop and set days to maturity.
4. Set spring offsets from the last frost date.
5. Set fall offsets from the first frost date.
6. Press calculate to see planting and harvest ranges.
7. Download CSV or PDF to share your schedule.

Planning windows with frost records

Start with local last and first frost dates from your yard log, extension charts, or station normals. The calculator converts those anchors into a planting window for each crop, so you can see when to sow, transplant, and expect first harvest with fewer surprises.

Interpreting offsets for sowing and transplanting

Offsets are measured in days from the frost date you select. Negative values represent days before frost, useful for cool-season greens and brassicas. Positive values represent days after frost, common for warm crops such as tomato and cucumber. Tighten the window for limited bed space, or widen it for staggered succession. When using transplants, set the start offset to match your hardening period and soil temperature goal.

Using maturity days to protect fall crops

Days to maturity links planting dates to harvest expectations. The calculator also adds a harvest span to represent staggered picking, for example 10–14 days for lettuce or 14–21 days for cucumbers. For fall planning, it compares your fall window against a latest safe planting date: (first frost minus buffer) minus maturity days. If your window extends past that point, the status becomes Caution to prompt variety, protection, or timing changes.

Applying buffer days for microclimates

Buffer days reduce risk in exposed sites, windy ridges, and low spots that frost early. Increasing the buffer moves the safe spring start later and the safe fall deadline earlier. A 7‑day buffer is a practical baseline for mixed gardens; raise it to 10–14 days for high elevation, and reduce it to 3–5 days for sheltered plots with thermal mass.

Turning schedules into bed and succession plans

Once dates are generated, group crops by planting windows to batch tasks and share row cover resources. Pair quick crops with long-season crops to keep beds occupied, such as lettuce before tomatoes, or radish before peppers. Export the schedule as CSV for spreadsheets, or PDF for field notes, then update offsets after each season.

FAQs

1) What if I do not know my frost dates?

Use regional averages from local agriculture offices, weather normals, or a nearby station. Then refine the dates over time using notes from your own garden and microclimate observations.

2) How should I choose buffer days?

Start with 7 days. Increase the buffer for exposed sites or higher elevation. Reduce it for protected areas with walls, paving, or tree cover that slow heat loss overnight.

3) Do offsets represent seeding or transplanting?

They represent the field action you want to schedule. For direct sowing, use sowing offsets. For transplants, use planting-out offsets and handle seed-starting separately based on indoor lead time.

4) What does a Caution status mean in fall?

Caution indicates the fall planting window may extend beyond the latest safe date to reach maturity before buffered frost. Consider faster varieties, season extension, or shifting the window earlier.

5) How is the harvest range calculated?

The earliest harvest equals planting start plus days to maturity. The latest harvest equals planting end plus days to maturity plus harvest span, which accounts for staggered pickings and variable growth rates.

6) Why export to CSV and PDF?

CSV supports sorting, filtering, and bed planning in spreadsheets. PDF is useful for printing, field notes, and sharing a stable version with helpers or clients during busy planting weeks.