After the flowers die in late spring and the poppy heads dry up with the seeds in them, do next year’s flowers come from these seeds falling to the ground? Or do next year’s flowers come from the small plants already growing in the garden right now? Its hard to imagine that these small green plants will survive the winter. If from the seeds, when should the seeds be planted?
If your poppy is a perennial, next year’s flowers may come from the “parent” plant that went dormant earlier this summer and/or from seeds that fell to the ground. Annual poppies grow from seed. The small plants you mention that are in the garden now (early September) likely grew from seed, and will produce some of next summer’s lovely flowers.
A poppy (genus Papaver) may be an annual, biennial or perennial plant. Perennials may only live for 2 or 3 years and some varieties [e.g., the alpine poppy (P. alpinum)] is so short-lived it may act like an annual or biennial.
Although easy to grow from seed, a perennial [e.g., the oriental poppy (P. Oriental group)] is generally propagated from root cuttings (taken once the growing season has ended). Once the plant has bloomed, cut it back hard to 7 cm (3 inches) high. Give it a shot of plant food and mulch it to ensure it retains moisture. This strategy may encourage a second flowering later in the growing season. On the other hand, by not cutting back the plant, a seedpod will form on the flowering stem, enabling the plant to self-seed, which may help keep it going for more than a few years. This perennial poppy has deep roots that spread well, and may need dividing every 5 years or so.
Annual poppies (e.g., the Flanders poppy (P. rhoeas) and opium poppy (P. somniferum) grow from seed and self-seed very well.
If you prefer to sow the seeds yourself as opposed to leaving the plants to self-seed, harvest the seeds when the weather is dry (the seeds should be dry and rattling inside the pods). In Ontario’s climate, it is recommended to sow the seeds in very early spring [they need freeze/thaw conditions in order to germinate], and covered with a thin layer of soil (they need sunlight to germinate). Keep the seedbed moist until tiny plants emerge (usually from 7-28 days – this depends on the temperature of the soil) – note that the plants do tolerate frost. The plants should flower in late spring or early summer and seed pods will mature about 80-90 days following planting – ready for the next harvest.
For more information, see
Utah State University Cooperative Extension. Seed poppy in the garden.
Toronto Master Gardeners. Sowing poppy seeds in July.