helictotrichon sempervirons (Blue Oat Grass)

10 years ago

I came across this forum while researching invasive ornamental grasses. Now i am a member--here's my first post. Blue Oat Grass is one of my favorites. I started with the requisite 3 some years ago and love their shape and color in the garden. But alas, they have to go. They were not invasive at first and I remember being pretty excited when I saw the first volunteer. However, that was a bad sign: A couple years later I am pulling them out from everywhere in the garden. If you don't get them when small, of course, they are harder to pull and I've even had to dig up a couple of invaded perennials in order to remove the grass. I read several postings about this grass, including comments such as "seeds seldom germinate." The only thing I can figure out about my grass is that I am witnessing the result of its crossing with another grass species, perhaps the pesky blue fescue I am getting rid of. I am curious if anyone on this forum has also experienced the heartbreak of good grass going bad.

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Comments (4)

donn_
10 years ago
My worst self-sowers have been Pennisetum alopecuroides 'Moudry' and Eragrostis spectabilis. I call them Ornamental Weeds.

H. sempervirens and Festuca glauca get haircuts before the seeds go viable. I leave one bed with a couple of each alone, to encourage volunteers, and then select the best for unique characteristics. Blue Fescue out-paces Blue Oat, in volunteer production, by 10:1.
gardengal48 (PNW Z8/9)
10 years ago
I live in the PNW and have grown, sold and spec'd for clients ornamental grasses for over 20 years. During all that time I have never encountered any issue with blue oat grass seeding or spreading. And I have used it alot!

My biggest sinners in that regard are the bronze sedges (Carex flagellifera and buchananii), New Zealand wind grass (Anemanthele lessoniana) and Mexican hair grass (Nassella tenuissima). And the usual culprits - golden millet, ribbon grass, etc.
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POGrower
Original Author
10 years ago
Thanks for response. Yes, I too think the fescues are the most "prolific" ornamental grasses. The carex sedges spread themselves around as well, but not nearly as boldly and I do like them. As for my blue oat grasses, I am going to clear them all out along with the fescues. Then I will add some new blue oat plants. I'm convinced my current plants have either reverted or engaged in promiscuity with other types of grasses. And each generation carries on the bad traits.
gardengal48 (PNW Z8/9)
10 years ago
Reverted to what? A species cannot revert to something else, although a hybrid could. Helictotrichon sempervirens is not a hybrid......not even that many named forms. And intergeneric hybrids are not very common, so I doubt that is an answer either.

FWIW, other than the few grasses I mentioned, I have never encountered seeding issues with any other ornamnetal grasses in this area, and specifically with the fescues or oat grasses. Western Washington summers tend to be cool enough that many ornamental grasses do not set seed readily or that seed never has a chance to ripen.