Vegetable and Weed Degree-day Models

Croptime introduces degree-day (DD) models for vegetable varieties and weeds. Vegetable DD models can help schedule planting dates and predict harvest dates more accurately than calendar days. Weed DD models can predict development of first germinable seed, and help reduce the risk of weed seed rain. Currently we have online models for:

  • Broccoli: four transplanted cultivars
  • Cucumber: one transplanted and six direct-seeded cultivars
  • Snap beans: three direct-seeded cultivars
  • Sweet corn: six direct-seeded and three transplanted cultivars
  • Sweet pepper: four transplanted cultivars
  • Tomato: four transplanted cultivars
  • Weeds: hairy nightshade, lambsquarter and redroot pigweed

New models will be posted online when available. Spinach, carrot, parsnip, lettuce, cauliflower, cabbage, kale, and summer squash models are expected soon.

Croptime Calculator Go to the calculator to use the DD models  


Vegetable Degree-day Models: An Introduction for Farmers and Gardeners: This Extension Publication explains how degree-day models work, describes how Croptime models are developed, and provides model parameters for Croptime models.

How-to Video: This nine minute video walks you through the basic steps to use the DD models

Quick Guide: Tri-fold brochure with step-by-step guide to using Croptime

Educational Slides: 53 Croptime teaching slides. Request PowerPoint format from Nick Andrews

Croptime Growth Stage Guide: 38-page guide that describes vegetable growth stages and provides instructions and a data sheet for collecting crop development data for new vegetable degree-day models.


If you have questions or comments, or are interested in collaborating to develop new DD models, please contact Nick Andrews.