Back in May, I wrote my first post about determining if a plant was a weed or wildflower. You might have been out in your yard and come across a plant that strikes you as pretty, but you don’t remember planting it. The thought may cross your mind, “Is this a weed or a wildflower?” In other words, “Should I be nurturing this plant or killing it?”
The plant I’d like to highlight this month has prickly leaves like a thistle and stiff branches. It holds 
stunning, enormous white blossoms through the heat of midsummer. I notice it often in neglected gravel yards, along roadsides and dotting naturalized areas. The leaves look so vicious it makes me think it has to be a weed, but the flowers seem too beautiful to be growing from a problem plant.
And the answer is…WILDFLOWER. This is prickly poppy (Argemone polyanthemos). What a neat plant. Native to most of the central states, it has a lifespan ranging from just one growing season (annual) to a couple of years (perennial). Because its leaves are so sharp, deer and rabbits don’t bother eating it.
Prickly poppy has three outstanding attributes. First, the flowers are big and white. This mean it’s an eyecatcher. Nothing stands out in landscape more than white flowers.
Second, it blooms for a long time. In Colorado Springs, it seems to bloom continuously from June through August when other plants are wilting in the heat.
Third, once it’s established, it thrives without much supplemental irrigation. So, lots of beautiful flowers in midsummer with little water? That’s my kind of plant.
How do you add it to yard? I’m not quite sure. I’d love to hear any success stories from readers. I’ve tried transplanting potted plants with very little success. Most of the transplants died after the first growing season.
Although I haven’t tried growing it from seed myself, several sources say it germinates fairly easily. If you have space in an area with rock mulch where seeds are likely to germinate, it might be worth spreading some seeds and seeing what happens.
If you’re lucky enough to have plants grow, you might be able to keep a population going by letting the plants produce seed each year. Don’t remove the seed pods before they open. A neighboring house in my area seems to have had good success with this approach.
Just make sure you sow the seed away from sidewalks, pathways, and patios. The leaves are not friendly. Rather than being “warm and fuzzy,” they truly are “cold and prickly.” Well, prickly at least.
If you succeed in getting prickly poppy to grace your landscape, I guarantee the results will delight you every summer. This is one native plant that deserves to be including in more Colorado landscapes.
Thank you so much about the info on the prickly poppy. I just saw some today for the first time at Red Rocks Park and came home to look in my 2 Wildflower books, and neither one of them had it. I got some seeds and hope to plant some next spring.
Hi Kayla, so glad the post was helpful. I agree…it’s such a beautiful plant. Good luck with the seeds. Please let us all know how it turns out!
I came across this website because I have prickly poppy in my yard, and I’m not sure how to care for it now that fall is approaching and it is finishing up its blooming. Some of it is starting to wither and turn grey, so I wasn’t sure if I should cut it back, how much to cut, etc. Any ideas? It is funny because I bought two little plants last summer at the Horticulture Society’s plant sale. That first summer they barely grew and one of them put out one, lonely bloom. So, I didn’t expect much this year, but they absolutely exploded! They grew several feet tall and were covered with blooms. I want to be careful with how I handle them now since I would definitely like them to come back next year.
Hi Delores, glad you found the site! Prickly poppy is a wonderful plant. I’ve experimented with growing it from transplants and seed. I’ve found that most prickly poppy plants are annuals. In other words, they grow and flower in one summer, then die. Before I understood that, I kept thinking I was doing something wrong and killing them. Instead, they just have a short life cycle. So, that’s very lucky that you got them to make it through last winter. If you’d like them to come back, my advice is to let the seeds mature on the plant until the seed capsules open. Since prickly poppy flowers all summer, there will be seed capsules at different stages of maturity on the same plant. When the capsules open, either you or Mother Nature can spread the seed around your yard and hope you get some seedlings next spring. They seem to germinate in areas with bare soil the best (without mulch). I wouldn’t cut the plant back or remove it even though it’s dying. Just let it be until it produces its seeds. Getting new plants is hit or miss, but I find in areas where growing conditions are favorable, you’ll have new plants germinating in different places for years to come. I hope you get some!