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Seasons and Greenhouses

Chill Hour Completion Calculator

The calculation of chill completion depends on chill hours accumulated and chill requirement. This page shows the relationship and a worked starting case.

Enter values for chill completion

Keep Chill Hour Completion units with their measurements.

hr

Enter the observed value for chill hours accumulated.

hr

Use the value that represents chill requirement.

From chill hours accumulated to chill completion

chill completion = chill hours accumulated ÷ chill requirement × 100

Chill Hour Completion compares Chill hours accumulated and Chill requirement and reports the relationship as a percentage.

For the prefilled measurements—chill hours accumulated at 720 hr and chill requirement at 900 hr—the calculated answer is 80.00%.

Interpreting this chill completion value

The calculator reports chill completion first. A fair comparison requires the same unit convention in each case.

Chill requirement remaining supplements chill completion in Chill Hour Completion.

Measurements for Chill Hour Completion

Chill completion is calculated from Chill hours accumulated and Chill requirement. Check the Chill Hour Completion units before editing. Compare this result with Daily Light Integral Calculator when daily light integral is also needed.

Chill hours accumulated
Chill Hour Completion currently demonstrates 720 hr; substitute the observation being evaluated.
Chill requirement
Default in Chill Hour Completion: 900 hr.

Collecting data for Chill Hour Completion

Place sensors near the crop zone and away from direct heater discharge or unrepresentative sun. Several points may be needed in a large structure.

Chill Hour Completion beyond the formula

Chill models are not interchangeable across regions. Use the Greenhouse Heater Capacity tool when required heater input needs its own calculation.

A zero Chill requirement leaves chill completion undefined in Chill Hour Completion. Keep heat loss in a separate Greenhouse Heat Loss Calculator case.

Documenting chill completion

Store the Chill Hour Completion date, Chill hours accumulated and Chill requirement, and Chill completion.

Separate measured chill hours accumulated from an assumed value so a later user can reconstruct the case.

Add the garden outcome as a new entry, using the same units and definition as chill completion. Light extension needed is available from Photoperiod Extension Calculator.

Chill hours accumulated: sensitivity example

Create a second case by setting Chill hours accumulated to 792 hr. The initial setting is 720 hr, and the corresponding chill completion values are 80.00% and 88.00%.

This keeps the effect of chill hours accumulated distinct from changes in the other Chill Hour Completion inputs.

Do not replace the source measurement merely because one scenario gives a preferred answer.

Before relying on chill completion

Can Chill Hour Completion guarantee field or greenhouse conditions?

No. The chill completion value reflects the entered dates or readings. Confirm it with a current forecast or sensors positioned near the crop.

Can Chill requirement be zero in Chill Hour Completion?

In Chill Hour Completion, zero chill requirement makes chill completion undefined.