Like our other blazing star, ten-petal blazing star is a denizen of some of our harshest environments while sporting ridiculously showy flowers. It's an oddball for sure. For one, it's a night bloomer. The giant white flowers open around dusk and close after midnight, but for that brief time they attract a multitude of pollinators, especially bees and moths. (Hairy evening primrose is also a night bloomer, should you want to create a dusk garden...)
This plant is biennial, meaning it completes its life cycle in two years. The first year it is a small rosette of thick, wavy leaves. The next year it blooms, producing a new flower or flowers each night in the hottest part of the summer. It is an effective reseeder, and seedhead 'capsules' will scatter the seeds for the next generation.
Ten-petal blazing star is tough, growing on steep dry sandy or rocky embankments. Up here in the Mission Valley, it grows on exposed and highly eroded slopes of ex-Lake Missoula sediments, but it is also found on railroad embankments and similar full sun, highly drained locales. In the yard, focus on: full sun and VERY WELL DRAINING soil (slopes or mounds are best!).
In my experience blazing stars don't like having their roots disturbed, so when planting, place the rootball in the hole without roughing it up, but make sure to press the backfill in adequately for good root/soil contact.
Final fun fact: ten-petal blazing star has slightly sticky foliage that seems to be an adaptation to trap small insects, making this plant a possible carnivore! You can read all about ten-petal blazing star in Montana naturalist Shane Sater's blog wild with nature.
First photo credit:
By Alaina Krakowiak
https://www.inaturalist.org/observations/54668262, CC BY 4.0
ten-petal blazing star
Mentzelia decapetala