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When to Plant Hollyhocks

Sow hollyhock seed outdoors any time from early spring until about two months before your first heavy fall frost. Plants from these sowings grow a leafy rosette, overwinter, and bloom the following summer. In the Arizona low desert, plant in February-March or October-November for bloom from April to June.

Your dates for hollyhocks

Set your ZIP code at the top of the page and we will work out when to plant hollyhocks 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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Hollyhocks planting dates by zone

JFMAMJJASOND Zone 4b Zone 5b Zone 6b Zone 7b Zone 8b Zone 9a
Sow 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.
ZoneSow outdoors
Zone 2aApr 7 to 21
Zone 3aApr 14 to 28
Zone 3bApr 5 to 19
Zone 4aApr 1 to 15
Zone 4bMar 27 to Apr 10
Zone 5aMar 22 to Apr 5
Zone 5bMar 20 to Apr 3
Zone 6aMar 18 to Apr 1
Zone 6bMar 12 to 26
Zone 7aMar 5 to 19
Zone 7bFeb 22 to Mar 8
Zone 8aFeb 15 to Mar 1
Zone 8bFeb 3 to 17
Zone 9aJan 19 to Feb 2
Zone 9bDec 20 to Jan 3

Spring dates before the last frost assume the soil has thawed and is dry enough to work. After a late or wet spring, wait for that even if the date has passed.

A long, forgiving window

Hollyhocks are hardy, so their timing doesn’t hinge on the last spring frost the way tender annuals do. Cornell says seed can be sown outdoors any time from spring until about two months before the first heavy fall frost. University of Wisconsin-Madison Extension in Chippewa County gives the same two options, spring or late summer, for plants that flower the following year. South Dakota State recommends sowing saved seed in early spring.

What the window can’t change is the biennial rhythm. Whether you sow in spring or late summer, the plants spend their first season as a rosette of leaves and flower the next summer, usually starting in June.

Spring sowing

Sowing in early spring gives seedlings a whole season to build their rosette and roots before winter. The dates for your zone above show the early-spring window.

There’s an occasional bonus. Illinois Extension notes that hollyhocks planted early can be treated as annuals, so some early spring plantings may bloom the same year, though most won’t. The University of Arizona chart lists 120 days from seed to bloom, but that figure comes from the desert’s long growing season.

Sow on the soil surface without covering the seed, since light aids germination, and keep it moist. Seedlings appear in 10 to 14 days.

Summer and late-summer sowing

Summer sowing is the natural timing for hollyhocks. It matches what self-sown plants do when ripe pods drop seed. Sow from midsummer up to the cutoff:

  1. Find your average first fall frost (a hard frost, not a light one).
  2. Count back about 8 weeks. That is Cornell’s latest outdoor sowing date.
  3. Sow before then so seedlings form rosettes before the ground freezes.

Keep late-summer sowings moist until the seedlings are up, because the uncovered seed sits right at the surface.

Setting out potted plants

South Dakota State calls potted transplants the easiest way to add hollyhocks. Set them 12 to 18 inches apart, and keep them well watered until they’re established. Check them before buying: the Wisconsin plant clinic advises looking for the orange spots of hollyhock rust so you don’t bring the disease home.

Letting them reseed

To keep hollyhocks blooming every year without replanting, let some flower stalks ripen. Seed is ready when the pods are completely brown and dry. You can let the pods drop seed where they stand, or collect the seed and scatter it where you want plants next year. Either way, the seedlings follow the same cycle and bloom a year later. With some plants flowering and others in their rosette year, the patch has blooms every summer.

Desert Southwest

The University of Arizona chart for the Phoenix-area low desert has two planting windows: February-March and October-November. Bloom runs from April through June, before the worst summer heat. There, hollyhocks may act as annuals or biennials. In West Texas, Texas Tech finds they behave as biennials or weak perennials.

Where frost is rare

In the Arizona low desert hollyhock is planted in late winter or fall and blooms April through June, behaving as an annual or biennial. Plants can wither in summer heat in the Southeast, and in damp or foggy coastal California rust is the main problem.

ZonePlanting months in Extension guides
Zone 9Feb-Mar, Oct-Nov (Arizona low desert, AZ1100)

Based on University of Arizona AZ1100 Flower Planting Guide for the Low Desert (Phoenix area); UC Master Gardeners of San Luis Obispo County (UC ANR) for coastal California notes. No UF/IFAS, Texas A&M or UH CTAHR hollyhock planting calendar was found. Warm-winter areas are matched to zones approximately, so use the months for your region.

How to grow hollyhocksYour full planting calendar

Questions

What is the latest I can sow hollyhock seeds?

Cornell's cutoff is about two months, or 8 weeks, before the first heavy fall frost. That gives seedlings time to form rosettes sturdy enough to overwinter.

If I plant hollyhocks in spring, will they bloom this year?

Usually not. Most hollyhocks are biennials that bloom the summer after sowing, though Illinois Extension notes early-planted hollyhocks can be treated as annuals.

Can I plant hollyhocks in the fall?

Seed sown in late summer works well in cold-winter areas, as long as it goes in before Cornell's 8-week cutoff. In the Arizona low desert, October-November is a main planting window.

Sources