When to Plant Thyme

Spring planting in frost areas

Thyme is hardy once established. Penn State simply says to plant in spring, and setting young plants out once the danger of frost has passed is the safe choice. For most gardens that means from your average last frost date to about two weeks after it; the dates for your zone above show the window for your ZIP code.

Soil conditions matter as much as the date. Thyme rots in wet soil, so in clay or poorly drained beds, wait until spring rains ease and the soil has dried enough to crumble, or plant in a raised bed or rock garden. Water new plants regularly until they are growing, then cut back.

Spring is also the time to make more plants. NC State says transplanting and dividing are best done in early spring, and Penn State recommends taking 4-inch cuttings of new growth in late spring.

Why not fall in cold regions

In zones 5 and 6, a fall-planted thyme faces its first winter before it has had time to root in, and winter brings the risk of frost heaving. Colorado State recommends mulching thyme after the first of the year to prevent frost heaving and notes that cooking thyme is not reliably winter hardy in Colorado, where it may be grown as an annual. Plant in spring, choose a hardy cultivar such as ‘German Winter’, which Penn State describes as very winter hardy, and give it a full season to root.

Fall and winter planting in warm regions

Where winters are mild, thyme grows best in the cool, dry months and struggles in summer heat, humidity and rain.

Florida: UF/IFAS gardening calendars list thyme for November-December in North and Central Florida and November through January in South Florida. UF/IFAS Gardening Solutions says it can be planted from seed in late fall or early spring.

Desert Southwest: University of Arizona lists two planting windows in Tucson, October-November and February-April. Fall planting lets roots establish before summer heat; spring plantings need extra attention to watering as days get longer and hotter.

Texas and California: extension services there don’t publish a month-by-month thyme calendar, so use the frost-based dates for your zone above.

Seed timing

Seed is the slowest route. NC State notes germination is uneven, and Penn State says seed-grown plants may take several years to reach full harvest size. Penn State suggests sowing in spring, either in a seed tray or scattered directly on the ground, then keeping seedlings moist and thinning to about 12 inches apart. No extension source gives a specific number of weeks for starting thyme indoors.

When to expect a harvest

Take only a few sprigs the first year, whatever you planted. University of Delaware Master Gardeners list about 90 days to harvest for English thyme, 90 to 100 days for lemon thyme and about 180 days for common thyme. From the second year on, harvest from spring through summer, with the heaviest cut just before or as the plant begins to flower.