How these dates are worked out
Extension services time bulb planting by soil temperature (below about 60°F) and by the ground freeze (plant four to six weeks before it), not by a calendar date. We don’t have soil or ground-freeze records for every station, so we use the first fall frost as a stand-in. For every NOAA station in a state that records frost regularly, we take the median first fall frost date (32°F reached in half of years), then take the median across stations. The window runs from about two weeks before that date to about three weeks after it.
That rule is our own rule of thumb, not an official one. We chose it because it lines up with published state calendars: mid-September to mid-October in South Dakota (South Dakota State University Extension), late September through October in Nebraska (University of Nebraska–Lincoln), and October in Iowa (Iowa State University). Near the coast, where the ground freezes late or not at all, it can run a week or two later than local calendars; Rutgers, for example, gives mid-September through October for New Jersey. Your own soil and your state or county extension office are the better guide, and mountain and valley stations in one state can be a month apart, so check your ZIP for the dates nearest you.
Signs it’s time to plant
- Soil below 60°F at planting depth (6 to 8 inches for tulips and daffodils). University of Wisconsin–Madison Extension says around 50 to 55°F or lower. Our soil temperature guide explains how to measure it.
- Nights in the 40s. South Dakota State University Extension uses nighttime temperatures staying around 40 to 50°F as the cue to start.
- The first frost has come or is close. In much of the country that happens at about the same time, which is why the table above is built from frost dates.
- Before the ground freezes. Keep planting until a couple of weeks before the soil freezes, per Wisconsin Extension.
Warm climates
Where frost comes late or rarely (California, Florida, Hawaii, Louisiana, Puerto Rico, Texas, U.S. Virgin Islands), a frost-based window stops being useful, and many bulbs don’t get the winter cold they need. Hardy daffodils often still do well in the upper South. Tulips and hyacinths in the warmest areas are usually chilled in a refrigerator for 6 to 12 weeks (never next to fruit, which gives off ethylene) and planted in late fall or early winter. University of Florida extension volunteers describe refrigerating tulips for about 8 weeks, planting from late November to mid-January and treating them as annuals. Your local extension office will know which bulbs perform in your area.
Planting basics
Choose firm, plump bulbs and a spot with at least five to six hours of sun and well-drained soil; bulbs rot in soggy ground. Plant two to three times as deep as the bulb is tall, measured from the base, which is about 6 to 8 inches for tulips and daffodils and 3 to 4 inches for small bulbs like crocus. Set them pointed end up, water them in, and add 2 to 3 inches of mulch once the ground freezes. Where squirrels dig up tulips and crocus, Wisconsin Extension notes that daffodils are left alone because they are poisonous to them.
Questions gardeners ask
When should I plant tulip and daffodil bulbs?
In fall, once the soil at planting depth has cooled below about 60°F and nights are in the 40s, and ideally four to six weeks before the ground freezes so the bulbs can grow roots. University of Nebraska–Lincoln and Rutgers extension both put this at mid or late September through October in their states; Iowa State calls October ideal.
Is it too late to plant bulbs?
Usually not, as long as you can still dig. Iowa State University says tulips and other spring bulbs can go in as late as late November or early December if the ground isn’t frozen. Late bulbs have less time to root, so water them in and mulch after the ground freezes. Bulbs left in the bag over winter will dry out, so planting late is better than not planting.
What happens if I plant bulbs too early?
Bulbs planted into warm soil in late summer can start to grow leaves in fall, and warm soil favors rot. Waiting until the soil is below 60°F avoids both. If bulbs arrive early, store them somewhere cool, dry and airy (Nebraska suggests 60 to 65°F) and away from ripening fruit.
Do I need to chill tulip bulbs before planting?
Only where winters are too warm to chill them naturally. Tulips need weeks of cold to flower properly. Florida extension advises refrigerating bulbs for about 8 weeks and planting from late November to mid-January, and treating tulips as annuals. Most of the country does not need this.
Which state plants bulbs earliest?
Of the states in this table, Alaska has the earliest typical first frost (Sep 22), so planting there runs from about Sep 8. Leaving out the warm-climate states, Arizona has the latest (Nov 13), with planting around Oct 30–Dec 4.
Related
- When to plant garlic, by state
- Planning a fall garden
- Soil temperature for planting
- How frost dates work
- Frost dates by state
Sources: NOAA NCEI 1991–2020 U.S. Climate Normals (frost dates); planting guidance from South Dakota State University Extension (Bulbs to Plant in the Fall), University of Nebraska–Lincoln Extension (G1742, Spring Flowering Bulbs), Iowa State University Extension (Yard and Garden), Rutgers Cooperative Extension (FS1220, Spring Flowering Bulbs), University of Wisconsin–Madison Extension Horticulture and UF/IFAS Extension Okaloosa County Master Gardeners. Long-term averages, not a forecast.