When to plant tulips and daffodils and dig up dahlias where you live

Spring bulbs go in the ground in fall, and dahlia tubers come out of it. Both jobs hang on the same two dates: the first fall frost and the first hard freeze at the weather station nearest you, plus your USDA zone.

Fall dates by USDA hardiness zone

Median dates across the ZIP codes in each half zone. Your own ZIP code above is the better answer, because frost dates vary a lot within a zone.

Zone	First frost	Hard freeze	Tulips	Daffodils	Peonies	Dahlias
3b	Sep 24	Oct 2	Plant by Sep 24	Plant by Sep 24	Early fall, eyes 1–2 in deep	Dig Sep 24–Oct 2
4a	Sep 28	Oct 7	Plant by Sep 28	Plant by Sep 28	Early fall, eyes 1–2 in deep	Dig Sep 28–Oct 7
4b	Oct 1	Oct 11	Plant by Oct 1	Plant by Oct 1	Early fall, eyes 1–2 in deep	Dig Oct 1–Oct 11
5a	Oct 4	Oct 16	Plant by Oct 4	Plant by Oct 4	Early fall, eyes 1–2 in deep	Dig Oct 4–Oct 16
5b	Oct 10	Oct 22	Plant by Oct 10	Plant by Oct 10	Early fall, eyes 1–2 in deep	Dig Oct 10–Oct 22
6a	Oct 16	Oct 28	Plant by Oct 16	Plant by Oct 16	Early fall, eyes 1–2 in deep	Dig Oct 16–Oct 28
6b	Oct 22	Nov 1	Plant by Oct 22	Plant by Oct 22	Early fall, eyes 1–2 in deep	Dig Oct 22–Nov 1
7a	Oct 25	Nov 4	Plant by Oct 25	Plant by Oct 25	Early fall, eyes 1–2 in deep	Dig Oct 25–Nov 4
7b	Nov 1	Nov 11	Plant by Nov 1	Plant by Nov 1	Early fall, eyes 1–2 in deep	Dig Nov 1–Nov 11
8a	Nov 6	Nov 18	Pre-chill, then plant	Plant Oct–Nov	Fall, eyes ≤ 1 in deep	Dig or mulch heavily
8b	Nov 13	Nov 27	Pre-chill, then plant	Plant Oct–Nov	Fall, eyes ≤ 1 in deep	Dig or mulch heavily
9a	Nov 25	Dec 12	Pre-chill, then plant	Plant Oct–Nov	Fall, eyes ≤ 1 in deep	Leave in ground
9b	Dec 14	Dec 29	Pre-chill, then plant	Plant Oct–Nov	Fall, eyes ≤ 1 in deep	Leave in ground

There are no rows for zone 10 and up: frost is rare that far south, and the closest station that records it can sit a long way from your garden.

Hardiness zones come from the PRISM Climate Group (Oregon State University) ZIP code data behind the 2023 USDA Plant Hardiness Zone Map. We derived this table from that data; it is not the official USDA map.

Missed fall planting?

Plant tulips and other spring bulbs as soon as you can. Iowa State Extension says they can go in as late as December if the soil is not frozen; cover the bed with a few inches of straw, pine needles or leaves to give the roots more time before the ground freezes.

If the ground has already frozen, pot the bulbs and chill them for 12 to 16 weeks at 40 to 45 °F in a refrigerator, cellar or unheated basement, then bring them into a bright room at 60 to 65 °F to flower indoors.

Do not hold them until spring. Bulbs kept out of the ground over winter are likely to be dead by early spring.

How deep and how far apart to plant

Illinois Extension's rule of thumb is to plant bulbs two to three times as deep as they are tall, measured from the bottom of the bulb.

Plant	Depth	Spacing
Tulips, large types	6–8 in	4–6 in
Tulips, small types (Kaufmanniana, Greigii)	3–5 in	3–4 in
Daffodils	about 8 in	—
Small bulbs	3–4 in	—
Peonies (bare root)	eyes 1–2 in below soil; no deeper than 1 in in the South	—
Dahlias (spring)	4–6 in, tuber laid flat, eye up	—

A dash means none of the sources we read gives a figure.

Tulips and daffodils

Penn State Extension advises planting spring bulbs in fall, before the first frost. Iowa State notes that September is usually too early, because warm soil pushes leaves up in the fall, and that tulips can go in as late as December if the ground stays unfrozen. Illinois Extension adds that most bulbs can be planted until the ground freezes.

In warm zones the rule changes. The University of Georgia says spring bulbs there need 12 to 16 weeks at 40 to 50 °F before planting, so from zone 8 the calendar tells you to chill tulips in the refrigerator first. Clemson advises planting daffodils in October or November without waiting for the soil to cool, and names jonquil, tazetta, poeticus and species daffodils as the ones that grow reliably in the South.

Dahlias

The University of Georgia notes that dahlias are not reliably hardy outside zone 9 unless heavily mulched. Wisconsin Extension advises digging them before a hard freeze, and says the tops may die back from a light frost first. The calendar gives that window: from the first 32 °F night to the first 28 °F night.

Oregon State Extension adds that after a frost has killed the stems, the tubers can stay in the ground for a few days if no freeze is forecast, and should be dug the same day if one is.

Peonies

Peonies are planted in fall too, but not by the frost date. Iowa State Extension plants bare-root peonies in late summer or early fall, September in Iowa, with the eyes 1 to 2 inches below the soil, and says potted peonies can go in at any time during the growing season.

Clemson Extension also calls fall planting best, sets the eyes no deeper than 1 inch in the South, and warns that in zones 8 and 9 some varieties get too little winter cold to bloom. The calendar switches to that advice from zone 8.

Where the numbers come from

Frost dates are NOAA's U.S. Climate Normals for 1991 to 2020 at the weather station nearest your ZIP code. Zones are matched to ZIP codes from PRISM Climate Group data behind the 2023 USDA Plant Hardiness Zone Map; this is a derived table, not the official USDA map. Every figure is for the station, so a low spot or a sheltered wall can shift your garden by a week or more.

Sowing zinnias and sunflowers or planting dahlias in spring? Use the spring flower planting calendar.

Where the dates and rules come from

Frost dates are NOAA's 1991–2020 climate normals for the weather station nearest your ZIP code: the date by which, in half of the years, the first 32 °F night and the first 28 °F night had arrived. The rules for each flower come from the extension services listed below.