Gardening basics
Hardiness zones, explained
What your zone actually measures, how to read the zones on a plant tag, the difference between annuals and perennials, and how to grow plants that aren't "rated" for where you live.
Warda PatelDreamDrop Gardens, Plano TX8 min readUpdated October 2026
The short version
Hardiness zones in 30 seconds
- Your zone is based on the coldest temperature your area usually reaches in winter.
- A plant tag that says "Zones 5–9" means it should survive winter and come back in zones 5 through 9.
- Zones say nothing about summer heat, rain or soil, so they're a starting point, not a guarantee.
- You can grow plants outside your zone: as annuals, in pots, or with winter protection.
01What is a hardiness zone?
The USDA Plant Hardiness Zone Map divides the US into 13 zones based on one number: the average annual extreme minimum winter temperature. In plain words, that's how cold your coldest night of the year usually gets.
Each zone covers 10°F and is split into two halves, "a" (colder) and "b" (warmer). Zone 8a's coldest nights average 10–15°F, while 8b averages 15–20°F.
Quick facts
- Based on
- Your coldest winter night
- Zones
- 1 (coldest) to 13 (warmest)
- Each zone
- 10°F, split into a and b
- Map updated
- November 2023
- "Zones 5–9"
- Comes back in zones 5 through 9
- Doesn't cover
- Summer heat, rain or soil
- Outside your zone
- Annuals, pots or winter protection
- Not sure of yours?
- Use Find your zone at the top
02The zone chart
Zones 3–11 cover almost all of the continental US. The temperature is the average coldest night of the year.
- Zone 3-40° to -30°F
- Zone 4-30° to -20°F
- Zone 5-20° to -10°F
- Zone 6-10° to 0°F
- Zone 70° to 10°F
- Zone 810° to 20°F
- Zone 920° to 30°F
- Zone 1030° to 40°F
- Zone 1140° to 50°F
Zones 1–2 (Alaska) and 12–13 (Hawaii and Puerto Rico) are on the map too.
03How to read the zones on a plant tag
When a tag says "Zones 5–9", the first number is the plant's cold limit: it should survive winters down to zone 5 and come back next spring. Colder than that, the roots or crown can freeze and die.
The second number is a nursery rule of thumb for the warm limit. In warmer zones the plant may suffer from long hot summers, or miss the winter chill it needs to bloom. Tulips, peonies and lilacs are classic examples.
- Zone 5 or colder: likely to die back in a hard winter without protection.
- Zones 6–10: comes back reliably each year.
- Zone 11: no winter chill to rest, so it blooms poorly.
04What zones don't tell you
A zone is a single winter number, so two places in the same zone can garden very differently. It doesn't account for:
- Summer heat
- Zone 8 covers both foggy coastal Oregon and humid Georgia. The American Horticultural Society's heat zone map tracks hot days instead.
- Rain and humidity
- Plants from dry climates can rot in wet winters, even in the "right" zone.
- Soil
- Alkaline clay, sand or acidic soil matters as much as cold for plants like gardenias and blueberries.
- Your yard
- A south-facing wall can be a zone warmer than an open low spot where cold air settles. These are called microclimates.
05Annuals, perennials and everything in between
Whether a plant "comes back" depends on both what kind of plant it is and whether it's hardy where you live.
| Type | What it means | Examples | How to grow it |
|---|---|---|---|
| Annual | Grows, flowers, sets seed and dies in one season. | Moonflower, flowering tobacco, cosmos | Replant every year, or let it self-seed. |
| Perennial | Lives three years or more. Many die back to the ground in winter and regrow in spring. | Peonies, heuchera, clematis, roses | Plant once; it comes back if it's hardy in your zone. |
| Tender perennial | A perennial in warm zones that can't survive a hard freeze. | Black elephant ears, canna, dahlias, aeonium | Leave in the ground in warm zones; elsewhere, grow as an annual or dig up and store. |
| Biennial | Leaves in year one, flowers in year two, then dies. | Foxglove, hollyhock, sweet William | Plant two years in a row once, then let it self-seed. |
06Can you plant something outside your zone?
Yes. Gardeners do it all the time. It just takes a plan for the season the plant can't handle.
If the plant needs a warmer zone than yours
- Grow it as an annual. Enjoy it for one season and replace it next year.
- Grow it in a pot. Move it into a garage, porch or bright room before hard freezes. Note that roots in pots get colder than roots in the ground, so a potted plant left outside is usually about one zone less hardy.
- Dig and store it. Bulbs, tubers and rhizomes like dahlias, canna and elephant ears can be lifted in fall and replanted in spring.
- Protect it. A thick layer of mulch, frost cloth on cold nights and a sheltered spot by a wall can buy you about half a zone.
If the plant needs a colder zone than yours
- Pre-chill bulbs. In zones 8–10, chill tulips and hyacinths in the fridge for 6–8 weeks (away from fruit) before planting.
- Choose low-chill varieties of fruit trees and peonies bred for the South.
- Give it afternoon shade and steady water so it gets through the hottest months.
07Can I grow it? Real examples
A few plants from our garden guides, and what to do if your zone falls outside their range.
| Plant | Rated | Your zone | What to do |
|---|---|---|---|
| Pillow Talk gardenia | 7–10 | Zone 6 | Grow it in a pot and bring it into a cool, bright room before the first hard freeze. |
| Black elephant ears | 8–11 | Zone 6 | Enjoy it as a summer plant. After the first frost blackens the leaves, dig the tubers and store them dry until spring. |
| Black Knight canna | 7–10 | Zone 5 | Same as elephant ears: dig the rhizomes in fall and replant after your last frost. |
| Black double tulips | 3–8 | Zone 9 | Winters are too mild for them to flower again. Chill the bulbs in the fridge for 6–8 weeks, plant in December, and treat them as annuals. |
| Summer Wine Black ninebark | 3–7 | Zone 8b | It may survive, but long hot summers stress it. Give it afternoon shade and steady water, and expect fewer flowers. |
| Black rose aeonium | 9–11 | Zone 7 | Keep it in a pot outdoors from spring to fall, and bring it in whenever nights drop below about 30°F. |
Your turn
Find your zone
Enter your ZIP code and we'll show your zone on every plant page, with a note when a plant needs extra care where you live.
Questions people ask us
What hardiness zone am I in?
Enter your ZIP code at the USDA Plant Hardiness Zone Map site, or use Find your zone at the top of our site. Your zone is based on the coldest temperature your area usually reaches each winter.
What does the 'a' or 'b' after a zone mean?
Each zone is 10°F wide and split into two 5°F halves. 'a' is the colder half and 'b' is the warmer half, so 8a is colder than 8b.
Did my zone change?
Possibly. The USDA released an updated map in November 2023 using weather data from 1991 to 2020. About half the country shifted half a zone warmer, so a plant tag or older chart may list a different zone than you see today.
Can I plant something outside my hardiness zone?
Yes, as long as you plan for it. Plants rated for warmer zones can grow as annuals, in pots you bring inside, or in sheltered spots. Plants rated for colder zones may struggle with your heat or not get enough winter chill to bloom.
What's the difference between an annual and a perennial?
An annual lives for one growing season. A perennial lives for years, but only comes back if it's hardy in your zone. A tender perennial lives for years in warm climates and is grown as an annual in cold ones.
Do zones tell me when to plant?
Not directly. Zones only describe winter cold. For timing, use your average last and first frost dates, or the planting calendar in our garden guides.