What Planting Zone Am I In? How to Find and Use Your USDA Zone

Your USDA planting zone is set by one number: the average annual minimum winter temperature where you live. To find it, enter your ZIP code on the USDA Plant Hardiness Zone Map and read what comes back, a number from 1 to 13 with an a or b attached. It takes a minute, and that number is what a plant tag means when it says hardy to Zone 5.

The harder part is knowing what to do with it. A hardiness zone tells you what will live through your winter. It does not tell you when to plant, and that gap catches out a lot of gardeners early on. Below is how to find your planting zone, what the number and the letter mean, and how to turn it into a sowing schedule.

How to find your planting zone in one minute

1. Open the USDA Plant Hardiness Zone Map at planthardiness.ars.usda.gov.
2. Enter your ZIP code.
3. Read the zone it returns: a number from 1 to 13, plus an a or b half.

Do not trust an old number. The USDA rebuilt the map in 2023 on newer thirty-year weather data, and about half the country moved up by a half zone: a yard that was 6a is often 6b now. If you are reading a zone off an old seed packet, look it up again.

What the number and the letter actually mean

Each zone is a 10 F band of average annual minimum winter temperature. Zone 5 covers -20 to -10 F, Zone 6 covers -10 to 0 F, and the bands step up 10 F at a time to Zone 13. The letter splits the band in half, 5 F each: a is the colder half, b the milder one. So Zone 7a runs 0 to 5 F, Zone 7b runs 5 to 10 F.

Two things people misread. It is an average of the coldest night in a normal year, not the coldest ever recorded, so a hard winter can still drop below it. And the scale is cumulative: a perennial hardy to Zone 5 also comes through a Zone 6 or 7 winter.

What your zone does and does not tell you

Your zone answers one question, and it answers it well: will a perennial survive the winter here. If you want lavender alive next April, check the zone first. Here is what it does not tell you:

• Your frost dates, spring or fall.
• How hot your summer runs, which decides whether peppers ripen or lettuce bolts.
• How much rain you get, or when it falls.
• Your soil, which does more for a crop than any map.
• Your day length, which drives onions.

That is why two gardens in the same zone can have last frosts weeks apart. Coastal Zone 8 in the Pacific Northwest and Zone 8 in central Texas share a winter low and almost nothing else. A north slope, a frost pocket, or a lot near a big lake each keeps its own schedule.

Put plainly: the zone tells you what survives the winter, the frost date tells you when to plant. For annual vegetables that distinction matters most, because an annual dies at the end of the season anyway. A tomato does not care that your winters bottom out at -10 F. It cares that a late frost in May will kill it. The number that governs your calendar is the frost date, not the zone.

How to use your zone to plan a planting schedule

The working rule is simple. Look up the average last spring frost for your area, mark it on a calendar, and count backward from it.

• 6 to 8 weeks before your last frost: start seeds indoors for tomatoes and peppers. Peppers are slower off the mark than most people plan for.
• 4 to 6 weeks before your last frost: start seeds indoors for brassicas such as broccoli, cabbage, and cauliflower.
• As soon as the ground can be worked: direct sow the cold-hardy crops. Carrots, beets, peas, radishes, and lettuce go into cool soil and would rather be sown early than late. A mixed vegetable seed variety pack covers most of that first sowing.
• After the last frost: harden off and plant out the tender crops, and direct sow beans, corn, cucumbers, and squash once the soil warms.

Enter your ZIP code in our planting calendar for your local frost dates and a month-by-month sowing schedule built around them. Every packet we ship also carries a QR code that opens a free growing guide for that variety.

Find your zone's planting calendar

Once you have your number, go straight to its calendar. Each one lays out what to sow, transplant, and harvest month by month.

• Zones 1 and 2 planting guide
• Zone 3 planting calendar
• Zone 4 planting calendar
• Zone 5 planting calendar
• Zone 6 planting calendar
• Zone 7 planting calendar
• Zone 8 planting calendar
• Zone 9 planting calendar
• Zone 10 planting calendar
• Zone 11 planting calendar
• Zone 12 planting calendar
• Zone 13 planting calendar

If your winters feel colder or milder than the calendar you land on describes, read the one on either side and see which fits better. Zone lines run through neighborhoods, not around them. And whichever zone you land in, look your frost dates up by ZIP code before you sow. That is the date the season turns on.

Frequently asked questions

What planting zone am I in?

Enter your ZIP code on the USDA Plant Hardiness Zone Map at planthardiness.ars.usda.gov and it returns your zone: a number from 1 to 13 with an a or b half attached. That number reflects the average annual minimum winter temperature at your address, and it is the same figure seed packets and plant tags mean when they say hardy to a zone.

What is the difference between 7a and 7b?

Both sit inside the Zone 7 band, which averages a winter low of 0 to 10 F. 7a is the colder half of that band at 0 to 5 F, and 7b is the milder half at 5 to 10 F. In practice, a 7b garden can carry slightly tenderer perennials through winter and often sees its last spring frost clear a week or so earlier.

Did the USDA zones change?

Yes. The USDA published an updated Plant Hardiness Zone Map in 2023, built on newer thirty-year weather records, and roughly half of the country shifted up by a half zone. Your garden did not change overnight, but the recorded averages did, so look your ZIP code up again instead of trusting a number you memorized years ago.

Does my zone tell me my frost date?

No. The zone is built from winter lows, not from when frost arrives and lifts. Two gardens in the same zone can have last frosts weeks apart depending on elevation, slope, and how close they sit to a city or a large lake. Look up your local frost dates separately, then build your sowing schedule around those.

Can I grow a plant that is rated for a warmer zone?

For one season, usually yes. Annual vegetables and flowers finish before winter arrives, so the hardiness rating barely matters. A perennial rated for a warmer zone will grow happily all summer but is unlikely to survive your winter outdoors unless you pot it up and move it in, or mulch it heavily in a sheltered spot.