March 2023 (revised/updated)
Suggested Vegetable Planting Dates: Grand and San Juan Counties
Reagan Wytsalucy, USU Extension Assistant Professor, Agriculture – San Juan County Cory Farnsworth, USU Extension Assistant Professor, Agriculture – Grand County Dan Drost, USU Extension Emeritus Vegetable Specialist
Introduction to Vegetables
“When should I plant?” and “What should I plant?” are two of the more common questions received from Utah gardeners. To answer the “When” question, you need to know something about the climate where you live. Vegetable plants vary in their response to temperature and are grouped by how they cope with cold or hot conditions. There are four (4) vegetable groups (Maynard, 2006), which include the hardy, half-hardy, tender, or very tender crops. These groups are also referred to as the cool-season (hardy or half-hardy) and warm-season (tender or very tender) vegetables (see Tables 2 and 3).
Warm-Season Vegetables
Cool-Season Vegetables
Warm season vegetables like warmer temperatures (range 55 °F to 90 °F), grow poorly or are damaged by temperatures between 32 °F to 50 °F, and do not survive frost events. Seeds germinate at warm soil temperatures (+60 °F), plants are large, and the plant parts eaten are immature and mature fruits. The tender crops grow well at lower warm temperatures and are planted sooner than the very tender vegetables.
Cool-season vegetables like moderate temperatures (range 40 °F to 80 °F), and many can survive frost events. Seeds germinate at cooler soil temperatures, plants are typically smaller, many are biennials, and the plant parts eaten are roots, stems, leaves, and immature flower parts. The hardy vegetables can withstand colder conditions and are often planted sooner than the half-hardy vegetables.
Local Weather Affects Planting Decisions
To decide “When to plant,” you need to consider the vegetable being grown and the unique weather conditions where you live. Since weather conditions vary greatly (day-to-day, year-to-year), climate scientists gather long-term weather observations to identify average conditions for a location. Gardeners and growers can use this information to help make planting decisions (“When to plant”) and determine if there is enough time to grow the crop of choice (“What to plant”). 1