Oswego, NY planting zone & frost dates

Oswego is in USDA hardiness zone 6a. The last spring frost usually comes around April 22 and the first fall frost around October 29, for a growing season of about 187 days.

USDA hardiness zone6aavg. extreme winter low -10°F to -5°F

Average last spring frostApril 2290% chance of no frost after May 7

Average first fall frostOctober 2910% chance of frost by October 9

Growing season187 daysfrost-free days in an average year

Planting calendar for Oswego

Dates are counted from the average last spring frost (April 22) using the typical timing recommended by U.S. extension services. Warm-season crops go out only after the danger of frost has passed and the soil has warmed.

Crop	When
Tomatoes	Start seeds indoors: Feb 25 – Mar 11 Transplant outdoors: Apr 29 – May 6
Peppers	Start seeds indoors: Feb 11 – Feb 25 Transplant outdoors: May 6 – May 13
Eggplant	Start seeds indoors: Feb 11 – Feb 25 Transplant outdoors: May 6 – May 13
Broccoli	Start seeds indoors: Feb 11 – Feb 25 Transplant outdoors: Mar 25 – Apr 8
Cabbage	Start seeds indoors: Feb 11 – Feb 25 Transplant outdoors: Mar 25 – Apr 8
Onions (sets)	Plant outdoors: Mar 25 – Apr 8
Peas	Sow outdoors: Mar 11 – Mar 25
Spinach	Sow outdoors: Mar 11 – Mar 25
Lettuce	Sow outdoors: Mar 25 – Apr 8
Carrots	Sow outdoors: Mar 25 – Apr 8
Potatoes	Plant outdoors: Mar 25 – Apr 8
Beans	Sow outdoors: Apr 29 – May 6
Sweet corn	Sow outdoors: Apr 29 – May 6
Cucumbers	Sow outdoors: Apr 29 – May 6
Squash & zucchini	Sow outdoors: Apr 29 – May 6
Basil	Start seeds indoors: Mar 11 – Mar 25 Transplant outdoors: Apr 29 – May 6

Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Sep 3 (8 weeks before the average first fall frost on Oct 29).

Useful for zone 6a gardens

Seed starting kit with dome — to start seeds indoors before the last frost
LED grow light for seedlings — stops leggy seedlings
Frost cloth / plant covers — for late spring and early fall frosts
Soil thermometer — warm-season crops need soil above 60°F
Cold frame / mini greenhouse — adds weeks to a short season

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Frost risk in detail

	90% chance	50% chance	10% chance
Last 32°F frost in spring is after	Apr 9	Apr 22	May 7
First 32°F frost in fall is before	Nov 11	Oct 29	Oct 9

How to read it: in spring there is a 10% chance of a frost after May 7, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 9. A hard freeze (28°F) usually ends around April 10.

Hardiness zone by ZIP code in Oswego

13126 zone 6a

Nearby cities

Fulton zone 6a, last frost Apr 27
Clay zone 5b, last frost May 4
Cicero zone 5b, last frost Apr 29
Fairmount zone 6a, last frost Apr 29
Auburn zone 6a, last frost May 2
Syracuse zone 6a, last frost Apr 29
Geneva zone 6b, last frost Apr 30
Watertown zone 5a, last frost May 2

All cities in New York → · Other zone 6a cities →

Questions

What growing zone is Oswego, NY?

Oswego is in USDA Plant Hardiness Zone 6a (average extreme winter low -10°F to -5°F), according to the USDA 2023 map.

When is the last frost in Oswego?

The average last spring frost (32°F) in Oswego is April 22. There is still a 10% chance of frost until May 7.

When can I plant tomatoes in Oswego?

Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Apr 29 – May 6. Start seeds indoors 6–8 weeks before the last frost.

Frost dates: NOAA U.S. Climate Normals 1991–2020, station Oswego, NY (USC00306314), 2.2 km (1.4 mi) from the city center, elevation 99 m, based on 28 years of records. Hardiness zone: USDA Plant Hardiness Zone Map 2023 for the ZIP code nearest to the city center. Microclimates (valleys, hills, cities, coasts) can be warmer or colder: check the local forecast before planting. How we calculate the data.