When to Plant Thyme in Colorado

Growing Thyme in Colorado: Complete Guide

Thyme (Thymus vulgaris) is a warm-season crop that needs a head start indoors before Colorado's last frost. Most Colorado gardeners begin seeds indoors around Monday, February 23, 2026 and move transplants outside around Monday, May 4, 2026, after the risk of frost has passed.

Because Colorado stretches across 7 USDA hardiness zones (4a, 4b, 5a, 5b, 6a, 6b, 7a), planting windows can shift by as much as six to eight weeks from one end of the state to the other. Gardeners in the warmer southern zones can start earlier, while those in cooler northern zones should wait until the zone table above shows their last frost has passed.

With 90 days to maturity, Thyme needs the indoor head start that Colorado's growing season requires. Starting indoors ensures you have strong transplants ready the moment outdoor conditions are right.

Thyme requires full sun (6+ hours) and low (drought tolerant) moisture. Most of Colorado receives adequate sunlight during the growing season, though gardeners in humid eastern regions should watch for fungal issues and ensure good air circulation.

For the most precise planting dates tailored to your exact location, enter your ZIP code on our planting calendar or use the zone table above to find the schedule for your area of Colorado.