Most garden poppies are cool-season flowers sown right where they will bloom, because they don't transplant well (MU Extension, Johnny's, Wildflower Center). In mild-winter areas, sow in fall for spring flowers (NC State); in cold areas, sow corn (Shirley) poppies as soon as the soil can be worked in spring (Johnny's). Iceland poppies can be started indoors 6 to 8 weeks before transplanting (Johnny's), and California poppies go in after the last frost or in fall (Johnny's, NC State). Oriental poppies are perennials planted as roots or potted plants; they go dormant in summer. Poppies are poisonous to pets (Pet Poison Helpline).
"Poppy" covers several plants. NC State counts about 100 Papaver species, and MU Extension says the poppy family holds about 600. This guide covers four common garden types: corn poppy (Papaver rhoeas, also called Flanders or field poppy; Shirley poppies are its selected forms, per MU Extension), Iceland poppy (P. nudicaule), Oriental poppy (P. orientale) and California poppy (Eschscholzia californica), which is in the same family but a different genus. MU Extension says most poppies prefer cool summers, and NC State says Iceland and Oriental poppies do best in cool climates. We don't cover the opium or breadseed poppy (P. somniferum), because its legal status varies; MU Extension notes that growing it is illegal in Missouri.
When to plant poppies
| Timing | What the sources say |
|---|---|
| Fall (most of the South and mild-winter areas) | NC State says fall plantings of Iceland and Shirley poppies flower in spring. The Wildflower Center sows California poppy seed in fall where you want it, and NC State says to sow California poppies in fall |
| As soon as soil can be worked in spring | Johnny's direct-seeds corn (Shirley, Flanders) poppy then; germination takes 14 to 21 days at 60 to 75°F. Iceland poppy can also be direct-sown in early spring (Johnny's) |
| 6 to 8 weeks before transplanting (Iceland poppy indoors) | Johnny's sows Iceland poppy in cells and says it germinates in 7 to 12 days at 65 to 75°F. Transplant young, and grow it where temperatures stay mostly below 70°F |
| After last frost (California poppy) | Johnny's direct-sows California poppy after the last frost, or sows it in cells 2 to 3 weeks before; NC State says it can be started indoors about 3 weeks before the last frost |
| Late summer to fall (Oriental poppy) | Oriental poppy foliage dies down after it flowers in early summer and comes back in fall (NC State). MU Extension says plants from seed bloom in their second or third year |
Our planting calendar shows your last spring frost and first fall frost. For annual poppies, the key is cool weather while plants grow: Johnny's says corn poppy needs to go in early, and California poppy needs cool nights. In our reading, if your summers get hot fast, a fall sowing gives poppies the long, cool run they want (GardenPal reasoning based on NC State and the Wildflower Center). Because the seedlings resent being moved, MU Extension suggests peat pots kept in a cool spot if you do start them early.
How to plant poppies
| Corn / Shirley | Iceland | California | Oriental | |
|---|---|---|---|---|
| Life cycle | Annual (Johnny's) | Short-lived perennial grown as an annual or biennial (MU Extension) | Cool-season annual; short-lived perennial in zones 8 to 10 (NC State) | Perennial, zones 3a to 7b (NC State) |
| Sun | Full sun; afternoon shade where it's hot (NC State) | Sun or part shade (Johnny's) | Full sun (NC State) | Full sun (NC State) |
| Soil | Fertile, moist, well drained (NC State) | Well drained (Johnny's) | Poor, dry, sandy or low-fertility soil (NC State, Johnny's) | Well drained; don't overwater the deep taproot (NC State) |
| Seed depth | 1/4 in, seed needs darkness (Johnny's) | On the surface (Johnny's) | Under 1/4 in (Johnny's); rake in lightly (Wildflower Center) | Usually bought as plants or root cuttings (NC State) |
| Spacing | 6 to 8 in (Johnny's) | 6 to 12 in (Johnny's) | Thin to 6 in (Johnny's) | NC State lists 2 to 3 ft tall plants |
| Height | 9 in to 1.5 ft (NC State); 12 to 24 in (Johnny's); RHS lists up to 75 to 90 cm | 15 to 20 in (Johnny's) | 1 to 2 ft (NC State) | 2 to 3 ft (NC State) |
Sources differ on seed depth, so follow your seed packet: Johnny's covers corn poppy seed 1/4 inch because it germinates in darkness, but surface-sows Iceland poppy. Poppy seed is tiny; mixing it with a little sand makes thin, even sowing easier (GardenPal suggestion, not from the sources).
Thinning, watering and deadheading
- Thin seedlings to the spacing above rather than moving them (Johnny's).
- Water lightly. Root rot is a risk in wet soil (NC State), and California poppy likes poor, dry ground (NC State).
- Deadhead to keep California poppies flowering (NC State) and to stop heavy self-seeding (MU Extension).
- Cut flowers: Johnny's cuts corn poppies when buds show color and sears the stem ends; NC State also says to burn the stem end. Johnny's gives a vase life of 2 to 4 days for corn poppy and 5 to 7 days for Iceland poppy.
Poppies in containers
Because poppies dislike root disturbance (MU Extension, Johnny's), in our view a pot works best if you sow straight into it and thin, rather than transplanting into it (GardenPal reasoning). Compact Iceland poppies, at 15 to 20 inches (Johnny's), are the easiest fit. Use a free-draining mix, since wet soil leads to root rot (NC State).
Fall, winter and summer dormancy
- Frost: NC State says poppies are frost tolerant, which is why fall sowing works in milder areas.
- Oriental poppy dormancy: foliage dies back after flowering in early summer and returns in fall (NC State, MU Extension). NC State suggests baby's breath or Boltonia nearby to fill the gap. NC State says it doesn't do well south of zone 7.
- Self-sowing: corn poppy reseeds vigorously and can turn weedy, and its seed can stay viable for decades (NC State). The Wildflower Center says California poppy can be weedy too. Remove seed pods if you don't want volunteers (MU Extension).
Pests and problems
Root rot in wet soil is the main problem (NC State). NC State also lists botrytis and powdery mildew on corn poppy, and RHS adds aphids, downy mildew and verticillium wilt. California poppy flowers close in cloudy weather and at night (NC State), which is normal. Each corn poppy flower lasts only about a day (NC State), but plants keep opening new buds.
Poppies around the vegetable garden
Annual poppies suit a sunny bed edge or a wildflower strip, where self-sown seedlings won't crowd out crops (GardenPal reasoning). Because they are poisonous to pets (Pet Poison Helpline), keep them out of areas where dogs graze. Corn poppy has been a symbol of remembrance since John McCrae's 1915 poem "In Flanders Fields" (MU Extension). For other cool-season flowers sown in place, see when to plant nigella, when to plant cosmos and when to plant calendula.
Frequently asked questions
When should I plant poppy seeds?
In fall where winters are mild (NC State), or as soon as the soil can be worked in spring (Johnny's). California poppy can also be sown after the last frost (Johnny's).
Can you transplant poppies?
They don't transplant well because of their taproot, so sow them where they will grow (MU Extension, Johnny's). If you start Iceland poppies indoors, move them young (Johnny's).
Do poppy seeds need light to germinate?
It depends on the type. Johnny's covers corn poppy seed 1/4 inch because it needs darkness, but surface-sows Iceland poppy seed.
Why did my Oriental poppy disappear in summer?
That is normal. The foliage dies back after flowering and comes back in fall (NC State).
Are poppies poisonous to dogs?
Yes. Pet Poison Helpline lists poppy as toxic to dogs. Call your vet if your dog eats some.
Do poppies come back every year?
Oriental poppies are perennials. Corn and California poppies are annuals in most gardens but reseed freely (NC State, Wildflower Center).
Enter your frost dates to time a fall or early-spring poppy sowing.
Open itSources
- Virginia Cooperative Extension, "Companion Planting in Gardening" (SPES-620P)
- University of Maryland Extension, "Vegetable Succession and Companion Planting"
- Oregon State University Extension, "Companion Planting"
- Penn State Extension, "Herbs Make Good Plant Partners and Companions"
- University of Minnesota Extension, "Planting the vegetable garden"
- USDA Plant Hardiness Zone Map
- NOAA NCEI U.S. Climate Normals (frost/freeze data)
- NC State Extension Gardener Plant Toolbox, "Papaver"
- NC State Extension Gardener Plant Toolbox, "Papaver rhoeas"
- NC State Extension Gardener Plant Toolbox, "Papaver orientale"
- NC State Extension Gardener Plant Toolbox, "Eschscholzia californica"
- Johnny's Selected Seeds, "Corn poppy: key growing information"
- Johnny's Selected Seeds, "Iceland poppy: key growing information"
- Johnny's Selected Seeds, "California poppy: key growing information"
- University of Missouri Extension (David Trinklein), "Poppy: a remembrance of fallen heroes"
- Royal Horticultural Society, "Papaver rhoeas" plant details
- Lady Bird Johnson Wildflower Center, "Eschscholzia californica"
- Pet Poison Helpline, "Poppy"
Pairings are summarized in our own words from extension-service guidance. Research support for many companion effects is limited, so treat them as good habits, not guarantees.