How to Grow Poppies

Sun

Full sun, at least six hours a day, produces the strongest stems and the heaviest flower display. The plant tolerates light afternoon shade in zones 8 and warmer, but anywhere with less than four hours of direct sun produces weak floppy growth and very few blooms.

Drainage

Poppies need sharp drainage. Seedlings rot quickly in cold wet soil, and damping off is the leading cause of failed sowings. Dig a one-foot test hole and fill it with water. If water sits more than a few hours, build a raised bed or work coarse sand into the planting area before sowing.

Soil

Lean to average soil produces the best plants. Heavily amended or fertilized soil pushes growth into leaves at the expense of flowers, and the stems flop under the weight of the blooms. Skip the compost amendments and rich potting soils.

Space and self-seeding

Scatter seed thinly so the seedlings come up at roughly 4 to 6 inches apart, then thin to a final 6 to 8 inches once true leaves appear. The plant self-seeds freely in a spot it likes, and many growers leave a few seedpods to dry on the plant each year for a self-sustaining patch.

Watering

Water gently and consistently during germination so the soil surface stays moist but never waterlogged. Once seedlings are established with true leaves, taper to deep weekly watering when rainfall is light.

Mature plants are fairly drought-tolerant and finish the season with little extra water in most years. Avoid overhead watering on open flowers, since rain and sprinklers shatter the papery petals.

Feeding

Skip the fertilizer. Poppies grown in even moderately rich soil produce lots of leafy growth and flop under the weight of the blooms. If the plants look genuinely starved by late spring, one very light application of a low-nitrogen bloom-booster fertilizer is enough.

Thinning seedlings

Thin seedlings to 6 to 8 inches apart once they have a few true leaves. Snip rather than pull to avoid disturbing the surrounding taproots. Thick stands of unthinned seedlings produce weak floppy plants with small flowers.

Deadheading or letting seedpods form

Deadheading extends the bloom period for a couple of weeks by stopping the plant from putting energy into seed production. For a self-seeding patch or a seedpod harvest, leave the spent flowers in place and let the pods form.

Once formed, the pods take 4 to 6 weeks to dry on the plant. They are ready when they rattle when shaken. Cut them then for arrangements or for seed collection.

End of season cleanup

The plants decline naturally as summer heat sets in. Pull or cut spent plants once they yellow, leaving any pods you want to drop seed in place. Many growers leave the dried stalks standing through midsummer to allow seeds to scatter for next year.

Bloom timing

Each bud opens for just a day or two before dropping its petals, but a healthy patch produces successive blooms over 2 to 3 weeks. Spring-sown plants flower in May or June depending on the zone. Fall-sown plants in zones 7 and warmer flower a few weeks earlier the following spring.

Color and form

The flowers come in white, pink, lavender, mauve, purple, and red, with single, semi-double, double, peony-form, and fringed selections available from seed. The papery petals look fragile but hold up well in calm weather.

Cutting for arrangements

Cut buds just as they crack open in the early morning and bring them indoors immediately. Sear the cut stem ends in boiling water for about 10 seconds, which keeps the sap in the stem and prevents wilting. The cut blooms last 3 to 4 days in a vase.

Dried seedpods

Once mature, the pods are decorative on their own and popular in dried arrangements. Cut stems when the pods rattle and hang upside down in a dry room for a few days to finish drying. The pods hold their shape for years.

Seeds fail to germinate

Usually sowing depth, not seed quality. The seed needs light to germinate and a thin layer of soil over it suppresses sprouting. Re-sow with seed pressed onto the surface and barely covered. Cold wet soil also delays germination, so wait for soil temperatures between 50°F and 65°F.

Seedlings collapse at the soil line (damping off)

A fungal disease that thrives in cold wet soil. Improve drainage, thin seedlings aggressively for airflow, and avoid overwatering young seedlings. Sowing on a slight raised mound rather than flat ground helps in heavy soils.

Weak floppy plants with few flowers

Most often a sign of too much fertility or too thick a stand. Thin to 6 to 8 inches apart and skip fertilizer next year. Plants growing in lean soil with proper spacing stand sturdier and produce more blooms.

Aphids on buds and new growth

Small green or black insects clustered on the buds just before flowering. Knock them off with a strong spray of water. Heavy infestations respond to insecticidal soap. Ladybugs eat aphids faster than any spray, so plant a few yarrows or sweet alyssum nearby to attract them.

Slugs and snails on seedlings

Ragged holes chewed in young foliage, often with slime trails visible in early morning. Hand-pick at dusk after a rain. Iron phosphate slug bait is safe around pets and works overnight.

Bolting and quick decline in summer heat

Poppies are cool-season annuals that naturally wind down once temperatures push past 80°F most afternoons. Plan for the plants to finish in early to mid summer. Replant the spot with a warm-season annual once the poppies are done.

Self-sown plants weaker than the parent

Common when too many seedlings come up in one spot and compete. Thin the volunteer patch the same way as a deliberate sowing. Also consider scattering fresh seed every couple of years to keep genetic diversity in the patch.

Petals shattered by rain

Open flowers drop their petals quickly in heavy rain or overhead watering. There is no fix once the petals are gone, but next year you can site the patch under a roof overhang or use drip irrigation to keep water off the flowers.