If I sow seeds from red poppies (from my mother’s garden) now (in July) will they germinate this year? Should I just leave them to self-seed or do I have to save the seeds and sow them next spring?
Although poppies adapt to all climate zones, you may need to experiment to find the right time to plant the variety you have on hand. The best time to plant is when the poppies have fully gone to seed (and would self-seed themselves – according to Mother Nature’s timetable) – this could be in the early fall or early spring.
In some cases, either of these times may work. If you don’t know when your poppies would self-seed, you can experiment by sowing some seeds in July, as some plants may germinate next spring, and some of the seeds in the fall. Save half the seeds in the refrigerator to plant the next spring, once the soil becomes workable.
Prepare the ground by putting compost or soil over the surface, and working it in lightly. The poppy seeds are so tiny, it’s best to just sprinkle them lightly over the surface of the soil (you can mix them with sand to make this easier) and tamp the soil down over them a bit with your hands. Don’t bury them, as they need some sunlight. Make sure the seeds scatter nicely so they don’t end up in clumps, as the emerging seedlings would crowd each other and have to compete and, so would not grow large.
Remember that poppies don’t like to be transplanted, so moving them as they emerge is not an option. The flowers should come up in the spring when the soil warms up and will reseed themselves each year. You should not have to plant the poppies again. If the seed you sow in spring does not germinate after a few weeks, fork the ground over gently to bring the seeds to the surface – the sunlight might help to trigger them to germinate.
Here’s a good overview of how to sow poppy seeds (note that many gardening sites mention spring and/or fall sowing):
Colorado State University – Extension2003: The Year of the Poppy https://www.coopext.colostate.edu/4dmg/Whats/2003popy.htm