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When to Plant Nasturtiums

In most of the country, sow nasturtium seed outdoors after the danger of frost has passed and the soil has warmed, from late spring into early summer. You can also start seed indoors in peat pots 4 to 6 weeks before your last frost. Where winters are mild, nasturtium is a cool-season flower: sow it in fall or winter so it blooms in late winter and spring.

Your dates for nasturtiums

Set your ZIP code at the top of the page and we will work out when to plant nasturtiums where you live, from the frost records of the nearest NOAA weather station. Your ZIP code is remembered on this device only.

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Nasturtiums planting dates by zone

JFMAMJJASOND Zone 4b Zone 5b Zone 6b Zone 7b Zone 8b Zone 9a
Start indoorsSow outdoorsFirst harvestDates use each zone's typical frost dates. Enter your ZIP code for your own.
Dates from each zone's typical (median) frost dates.
ZoneStart indoorsSow outdoors
Zone 2aApr 7 to 21May 19 to Jun 2
Zone 3aApr 14 to 28May 26 to Jun 9
Zone 3bApr 5 to 19May 17 to 31
Zone 4aApr 1 to 15May 13 to 27
Zone 4bMar 27 to Apr 10May 8 to 22
Zone 5aMar 22 to Apr 5May 3 to 17
Zone 5bMar 20 to Apr 3May 1 to 15
Zone 6aMar 18 to Apr 1Apr 29 to May 13
Zone 6bMar 12 to 26Apr 23 to May 7
Zone 7aMar 5 to 19Apr 16 to 30
Zone 7bFeb 22 to Mar 8Apr 5 to 19
Zone 8aFeb 15 to Mar 1Mar 29 to Apr 12
Zone 8bFeb 3 to 17Mar 17 to 31
Zone 9aJan 19 to Feb 2Mar 2 to 16
Zone 9bDec 20 to Jan 3Jan 31 to Feb 14

In frost country: after the last frost

Nasturtium is frost-tender. Wisconsin, Illinois, Maryland and Cornell all give the same basic instruction: sow outdoors once the danger of frost has passed. The University of Maryland adds that you should wait until the soil has had a chance to warm. Your average last frost date is shown with the dates for your zone above.

Wisconsin’s window runs from late spring to early summer. Germination takes about 7 to 10 days, depending on soil temperature. UF/IFAS’s zone-by-zone planting months run later still:

  • Zone 7: June and July
  • Zone 8: May and June

These months fall well after the last frost in each zone, so a sowing a few weeks past the dates for your zone above is not too late.

Starting indoors

Nasturtiums don’t transplant well, so direct sowing is the standard advice. If you want flowers sooner in a short-season area, Wisconsin suggests sowing indoors in peat pots 4 to 6 weeks before your last frost. Plant the whole pot after frost so the roots are not disturbed. Soaking seed for a few hours or overnight before sowing speeds germination either way.

How late can you sow?

Nasturtiums bloom until frost kills them, so the real deadline is how much bloom time you want before your first fall frost. Extension sources don’t give a seed-to-flower figure for summer sowings in the North. The University of Arizona chart lists 120 days, but that is for a cool-season fall-winter sowing in the desert. UF/IFAS notes that seed pods form about four months after sowing. So sow early enough to leave a full summer of growth, roughly by early summer in most northern gardens.

Midsummer heat is the other limit. The University of Maryland notes that nasturtiums grow best in early summer and fall weather, and heat-stressed plants produce harsher-tasting leaves. Seedlings sown into peak summer heat need steady watering and do better with some afternoon shade.

In mild-winter regions: fall and winter

Where frost is rare, nasturtium flips to a cool-season plant. It grows through the mild months, blooms in late winter and spring, and fades as summer heat arrives.

  • Arizona low desert (Phoenix area): the University of Arizona chart shows seed sown from October through January, with bloom from February into May.
  • Florida, zone 9: UF/IFAS lists March-April and October-November.
  • Florida, zones 10-11: UF/IFAS lists November through March. Its Gardening Solutions site is more relaxed and says nasturtiums can be planted from spring through fall across Florida and year-round in South Florida.

A freeze knocks plants back to the ground, so in the colder parts of zone 9 a fall sowing can be set back by a hard winter night. Wisconsin notes that in warm, mild climates nasturtiums can bloom and reseed year-round, so after one planting you may not need to sow again.

Where frost is rare

Where frost is rare nasturtium is a cool-season flower: sow in fall or winter for late-winter and spring bloom and expect plants to fade in summer heat. A freeze knocks plants back to the ground. In the Arizona low desert seed goes in October through January and plants bloom February through May.

ZonePlanting months in Extension guides
Zone 9Mar-Apr, Oct-Nov (UF/IFAS FPS-591); Oct-Jan in the Arizona low desert (AZ1100)
Zone 10Nov-Mar (UF/IFAS FPS-591); year-round in South Florida (UF/IFAS Gardening Solutions)
Zone 11Nov-Mar (UF/IFAS FPS-591 lists zones 10-11 together)

Based on UF/IFAS FPS-591 'Jewel Mix' nasturtium fact sheet (planting months by zone); UF/IFAS Gardening Solutions nasturtium page (spring-fall statewide, year-round South Florida); University of Arizona AZ1100 Flower Planting Guide for the Low Desert. Warm-winter areas are matched to zones approximately, so use the months for your region.

How to grow nasturtiumsYour full planting calendar

Questions

Can I plant nasturtiums before the last frost?

Not outdoors. Nasturtiums are frost-tender and die at the first freeze, so wait until frost danger has passed and the soil has warmed. Starting seed indoors in peat pots 4 to 6 weeks ahead is the way to gain time.

Is June too late to plant nasturtiums?

Usually not. Wisconsin's window runs from late spring into early summer, and UF/IFAS lists June and July as planting months in zone 7. Plants bloom until frost.

When do you plant nasturtiums in Florida?

UF/IFAS lists March-April and October-November in zone 9 and November through March in zones 10-11. Its Gardening Solutions site also says seed can go in from spring through fall statewide and year-round in South Florida.

Sources