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Herbs, Flowers & Specialty CropsHerb Garden Calendar by Zone
A herb calendar by zone is useful only if you know what a zone actually measures. This guide separates the winter-survival question, which zones answer, from the planting-date question, which frost dates answer.
Key points
- Zones show winter cold; frost dates guide planting.
- Sort herbs into hardy, half-hardy and tender before assigning dates.
- Treat average frost dates as planning points and keep protection ready.
- Use tested sources only when drying, freezing or otherwise preserving herbs.
What does your hardiness zone tell you about herbs?
USDA Plant Hardiness Zones describe the average annual extreme winter minimum temperature for an area. They help you decide which perennial herbs, such as thyme, sage or chives, will probably survive winter outdoors. They do not give frost dates, planting dates or growing season length.
Look up your zone on the USDA map, then compare it with the zone range listed for each perennial herb in your extension fact sheets. A herb rated for your zone will usually overwinter, though microclimates, wet soil and wind can change the outcome.
Which dates should you use instead of zones for planting?
Use your average last spring frost and average first fall frost. Extension offices, state climatologists and the National Weather Service publish frost date information, and Utah State and University of Illinois extension articles both caution that frost can arrive after the so-called average date, so treat it as a planning point rather than a guarantee.
For example, if your last spring frost usually falls around the end of April, you might sow hardy herbs outdoors a bit earlier and wait until after that date, or until nights are reliably mild, to set out tender ones.
Which herbs are hardy, half-hardy or tender?
Sorting your list by cold tolerance is the key step in a herb calendar. Hardy perennials come back each spring. Half-hardy herbs tolerate light frost. Tender herbs are damaged by cold nights and need warm soil.
Group the herbs you want into these three bins using a reliable extension plant list, then give each bin its own planting trigger.
Remember that a perennial herb can be hardy in your zone and still struggle in heavy, wet clay. Raised beds, gravel mulch or a sunny slope can make the difference for Mediterranean herbs that dislike wet roots.
- Hardy: can often be planted or sown early in spring and left outside through winter in suitable zones.
- Half-hardy: plant around the last frost, with row cover ready for late cold snaps.
- Tender: wait until after frost danger and warm soil; bring in or replant each year in cold zones.
How do you handle seeds versus transplants?
Some herbs grow readily from direct sowing in warm soil, while others are slow to germinate and are easier from transplants or divisions. Check the seed packet or extension fact sheet for each herb. Where the sheet gives a number of weeks to start seeds indoors before last frost, count backward from your own last frost date.
Harden off indoor-grown transplants over about a week by giving them gradually longer outdoor time, which prevents shock from wind and sun.
How should you harvest and preserve herbs through the season?
Light harvesting can begin once plants have enough growth to recover. Frequent cutting of tender-leaf herbs often encourages bushier growth, while woody perennials prefer lighter trims. Stop heavy harvest of perennial herbs some weeks before your first hard frost so new growth does not get nipped.
For drying, freezing or other preservation, use only tested procedures from the National Center for Home Food Preservation or your state extension service, and do not improvise methods.
Wash harvested herbs and handle them cleanly, and discard any that show mold. If you plan to sell herbs, ask your state department of agriculture about food safety and licensing rules for fresh or dried herbs.
What winter protection helps in colder zones?
Mulch after the ground has begun to cool can moderate freeze and thaw cycles. Good drainage matters as much as cold hardiness, since wet soil in winter kills many herbs that would tolerate the cold itself. In colder zones, consider growing tender herbs in pots that can come indoors.
Wind protection, snow cover and a site near a wall can shift conditions by a zone or so. Make notes each year of what survived.
How do you build your own herb calendar?
Start with a page listing your last spring frost, first fall frost and zone. Add each herb, its hardiness class and its trigger: soil workable, after last frost, after warm nights. Fill in your own dates after the first season, based on what actually happened. A calendar built from your own records is more accurate than any generic chart, because your yard has its own microclimate.
A last practical tip is to keep the calendar short. Four columns are enough: herb, hardiness class, planting trigger and harvest notes. When something fails, write the reason beside it. By the third season the page reflects your garden rather than a generic zone chart.
Sources and further reading
Last reviewed: November 2026. Educational information, ranges only. Confirm timing with your county extension office.