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Friday - June 03, 2011

From: Denton, TX
Region: Southwest
Topic: Propagation
Title: germinating Gulf coast penstemon and purple coneflower
Answered by: Guy Thompson

QUESTION:

I'm interested in propagating gulf coast penstemon (penstemon tenuis) from seed. Do I have to mascerate the 'berries' to remove the pulp from the seed, and do I have to stratify the seed to get the seed to germinate? In other words is a cold treatment such as stratification or overwintering necessary for germination. I'm also wondering what light regime works best-do they need light or darkness to germinate? If they need light would simple direct sowing by hand broadcasting work; and if they need darkness how deep should I sow the seed. Finally, can I get the seed to germinate this year before the winter sets in so I'll have a jump on next season? I also have another question about purple prairie cone flower (echinacea purpurea). In 'Native Texas Plants' the Wasowskis state that the centers hold their color and shape for a long time after the petals drop as the seed ripen. How long is necessary for the seed to ripen, how do you tell when the seeds are ripe, and is this process seen in other plants? I look forward to your responses.

ANSWER:

You should be able to get good results with your efforts to germinate Penstemon tenuis (Brazos penstemon) , commonly known as Gulf Coast Penstemon. This penstemon is known to reseed freely. However, like most penstemon species, it benefits from a cold treatment. (Sow under thin cover 3 wks @ 40ºF (4ºC) ) is the recommendation of an authoritative web site by Jim Swayne. I suggest that you wait until the seed pods dry and just begin to open (it shouldn't take long), then stratify if you hope to get germination the same season. No light is required.

With respect to Echinacea purpurea (Eastern purple coneflower), I think you should wait until the centers begin to turn dark and feel dry to the touch. Depending on the weather this should take a few weeks after the blooms fully open. The seeds should have reached maximum size by that time. Recipes for harvesting the seeds and germinating them are described in the attached article.

From the Image Gallery

Brazos penstemon
Penstemon tenuis

Eastern purple coneflower
Echinacea purpurea