Pennisetum setaceum 'Rubrum'

columbusgardenerAugust 29, 2006

Can this be grown from seed? I was told that the plants I purchased are sterile.

thank you


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It isn't sterile. In it's happiness zone, 9 and warmer, it's a self-seeder. It may not have enough season to develop viable seed in your zone, however.

    Bookmark   August 30, 2006 at 6:26AM
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Don have you tried growing it as an annual? I may try that route if I can find the seed. I have looked at a few sites for seed - but I am a bit overwhelmed.

thank you for the insight

    Bookmark   August 30, 2006 at 8:12AM
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I haven't, Debbie. I tried for 2 years to grow it from seed. I even concentrated on trading with warm zone seed traders, but never got a sprout. I've never seen the seed offered by commercial vendors, but found lots of it on the exchanges. Unfortunately, I think it was all harvested before it was ripe.

Lots of folks grow it as an annual, because it's so attractive, but I'm a skinflint, and seldom buy plants.

    Bookmark   August 30, 2006 at 9:46AM
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achnatherum(z4or3 Ontario)

This dialog has been going around as long as I have been growing grasses .... a long time.
My questions are:
Is there anyone on this forum that has actually had this grass self-sow.
if so, did it come true to type?
is it really proving to be perennial in Zone 9??

inquiring minds would love to know!

    Bookmark   August 30, 2006 at 12:02PM
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    Bookmark   August 30, 2006 at 12:43PM
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achnatherum(z4or3 Ontario)

Thanks for that informative link. It certainly did answer the question of Pennisetum setaceum 'Rubrum' being perennial in zone 9.
However, I didn't think that it spoke much to my question about self-sowing and certainly didn't say anything about coming true to form. So ..... taking a page from your book .. I emailed the author of the fact sheet and said,

"Dr. Gilman, Could you please answer a question with regards to an extension fact sheet
that you authored ; Fact Sheet FPS-464 - October 1999

A large group of Ornamental Grass lovers have a forum on the Garden Web where we discuss growing,propagating and all other topics relating to
ornamental grasses.

A topic that comes up regularly is the hardiness of Pennisetum setaceum
'Rubrum' and whether it can or cannot be grown from seed. Recently this topic resurfaced and one of the participants referenced your Fact Sheet. Your hardiness information is quite useful. But, I still have questions about the self-sowing aspect of this grass. (In my zone (USDA 5) this
cultivar does not appear to produce any viable seed.)
In your fact sheet you say; "However, it will reseed itself into surrounding landscapes. This could present a problem under certain circumstances."Does the cultivar produce as much viable seed as the species?
Do the seedlings come true to the cultivar or do they resemble the species?"
With his permission I copy his reply,

"The spcies has been documented in central florida as escaping. I am not aware of reports of the cultivar excaping."
Ed gilman

So, once again I wonder .....

    Bookmark   September 3, 2006 at 4:41PM
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I find it heartening that grass folks in all walks of life will respond to questions.

I think the fact that no commercial seed vendors offer seed for 'Rubrum' is a good indication that it's at least difficult, if not impossible to grow the cultivar from seed. It's a popular enough grass, that seed vendors would carry the seed if it would grow true 'Rubrum.'

I'm not sure there are any red or purple foliage grasses which can be grown from seed. I went through Jelitto's generous inventory, and the closest are the bronze colored Carex varieties, like C. buchananii and C. comans.

    Bookmark   September 3, 2006 at 5:03PM
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The consensus of the the authorities in this field (Darke, Greenlee and others) is that this grass is not a heavy seed producer and that what seed is produced is often - but not always - sterile. In California where many species of pennisetums are considered truly invasive and 'Rubrum' is sold widely, there is little evidence that this grass has escaped civilization and reseeded itself, giving a great deal of credence to the sterility theory. Even if seed is collected it is not considered a reliable means of propagation. Commercial production is done entirely with plugs.

I'd be very leery of sources offering this seed for sale. There are very few other OG's (can't think of any at the moment) that demonstrate these particular restrictive characteristics and I think unscrupulous vendors are banking on the lack of understanding the public has to promote their dubious merchandise.

    Bookmark   September 5, 2006 at 8:02AM
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achnatherum(z4or3 Ontario)

I agree with your 'consensus' ~ that's why I asked the question. I hate to quote the authorities blindly ~ they have been wrong :o)
I do think that most of the 'seed' offered in this case comes from individual gardeners rather than seed firms. There is always that assumption, if there is a seed head then there must be seed (viable).
Personally, I am quite happy with cultivars or varieties that are sterile. I have to cut back all my grass blooms in my propagation area to prevent seeding. I would be very hard to keep the cultivars separate if they started seeding into one another ~ which does happen in my garden.

    Bookmark   September 5, 2006 at 8:46AM
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I always get a chuckle when I see sellers of Rubrum seed on ebay or other sites. Then I sober up when I remember that some poor sole is buying these seeds under such false pretenses. Save the $ and start from divisions or plugs.

On a slightly different, but hopefully still on track topic...try Pennisetum Prince or Pennisetum Princess in zones too cold to grow Rubrum as a perennial grass. They are hardy (I believe) at least to zone 7...a solid 2 zones hardier than Rubrum. Great burgundy coloring...looks a bit more like a phormium to me than a pennisetum.

Here is a link that might be useful: Pennisetum Grasses

    Bookmark   September 20, 2006 at 8:49PM
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Grass guy..your link lists 'Prince' and 'Princess' as zone 8 hardy, and specifies they will not bloom if winter temps drop below freezing.

There's a fascinating account of their development and characteristics here.

    Bookmark   September 21, 2006 at 6:33AM
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Good link, donn! These are Dr Armitage's babies. The Athens Select program is big on these two grasses and I can see why. The hardiness isn't really verified yet, but of course everyone wants a hardy purple fountain grass.

Fountain grass is not quite what you get with these grasses, like I said, they look more like a phormium and you will not get the prolific blooming of a rubrum or a burgundy giant. Self-seeding is kind of a non-issue with these as well.

I'm positive that it won't be long till a hardy purple fountain grass is introduced. :)

    Bookmark   September 21, 2006 at 9:30AM
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Hi. Can anyone tell me when in the spring these actually get going. I had my garden made over last year and 10 of these lovely grasses were planted at the side of my house. We are now at the beginning of May and have had good Spring by UK standards. I am in the south of England so reasonably good climate. Anyway none of the 10 are showing any signs of life yet. Are the just late to get going or could there be a problem? Thanks in advance for any help

    Bookmark   May 3, 2011 at 7:40AM
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Julie..I would say it depends upon how far south in England you are. The hardiness zone maps show a very narrow coastal area which is zone 9, while much of the inland of South England is zone 8.

Pennisetum setaceum 'Rubrum' is not reliably hardy to zone 8. It may be the winter temperatures got your grasses, but they may also just be late starters. Tug lightly on the crown of the plant to see if you feel resistance. If the roots have a good hold on the soil, chances are the plants are ok. If not, they are goners. Pennisetums (hardier varieties) are just starting to show growth. They are the second latest grasses to start for me, just a bit earlier than Panicum.

    Bookmark   May 3, 2011 at 9:02AM
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buyorsell888(Zone 8 Portland OR)

I know the green fountain grass reseeds like crazy in Phoenix AZ but can't remember if the red does too. I'll have to look around when I am home in October.

I've never had any of the reds live over here in Oregon, even in my greenhouse. Lost Fireworks this year. Not sure why I keep trying....

    Bookmark   May 15, 2011 at 8:42PM
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