Black Eyed Susan Confusion

riversurfAugust 4, 2014

Hello, I'm hoping to get some help on how/when to cut back a black-eyed susan. Many of the blooms are well passed their prime and I've been cutting them off individually down to the second or third leaf.

Would it be better to just chop it all back to a height of 12-18" (or something) instead to, I'm hoping, promote a second round of blooms?

Thanks much

Steve

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gardenweed_z6a

It hasn't been my experience that black-eyed Susans are repeat bloomers. They bloom mid-summer where I am and the flowers last, literally, well into the fall. I've grown many varieties of BES over the years and have just left them alone to do their thing with no attention from me aside from admiration.

I was, however, surprised to find this sentence on the Missouri Botanical Garden's website: "Deadhead spent flowers to encourage additional bloom and/or to prevent any unwanted self-seeding." Looks like we both learned something new today.

If your BES flowers are well past their prime, they're simply producing viable seed for next year's plants. I find they do self-seed around my garden but since I love them, I just let them do so.

Here is a link that might be useful: Missouri Botanical Garden

    Bookmark   August 4, 2014 at 6:56PM
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dawgie(z7NC)

Goldfinches love BES seeds, which is one reason to let them go.

    Bookmark   August 4, 2014 at 8:31PM
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dbarron(z7_Arkansas)

Yeah, at this late stage in the year, I'd just let them go. If you have true BES, Rudbeckia hirta, it's a biennial and you need some seeds to continue.

    Bookmark   August 5, 2014 at 7:11AM
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riversurf

Thanks for the replies. I'm kind of torn. I have definitely seen secondary blooms--smaller and on shorter stalks--which started blooming about 3 weeks ago, and most of what I've read about some BES (mine is a perennial not a biennial) mention a strong possibility of secondary bloom periods (I'm at northern edge of zone 8). Most of the blooms are pretty ragged.

So this is why I'm still a little uncertain: deadhead individual blooms or just chop. If anyone has ever done the gross chop with some success (ie, a second, less impressive bloom) I'd love to hear about your experience.

Thanks!

    Bookmark   August 5, 2014 at 10:25AM
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ryseryse_2004

Rudbeckia 'Goldsturm' will probably not rebloom unless you live in a zone with a very late first frost. Here in Z5, they have just started blooming and will last for another few weeks. I don't cut them back because I love the way the yellow finches enjoy the seed heads.

    Bookmark   August 5, 2014 at 10:50AM
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riversurf

I think it's a Goldstrum. Because of Z 8's very long growing season, we often have some perennials and most annuals still flowering well into November. I've never seen a goldfinch feeding on the seeds, but that may be because the flowers are very close to a picture window.

    Bookmark   August 5, 2014 at 11:09AM
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dbarron(z7_Arkansas)

I've never noticed Goldfinches eating at Goldstrum either, but I've seen them and painted buntings eating at wild Rudbeckia hirta....and goldfinches would literally eat every green seed on my echinacea (never could collect seeds) long before maturity.

They were brazen about it...if startled away, they'd be back in 3 minutes.

    Bookmark   August 5, 2014 at 12:39PM
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pitimpinai(z6 Chicago)

riversurf, if you would like to prolong Rudbeckia's blooming season, I would like to suggest that you add R. triloba to your garden. It is a biennial and the last Rudbeckia to bloom in my garden and lasts until September. Mind you, R. triloba reseeds most prolifically for me. This Rudbeckia is much taller with flowers much smaller than any other R. If you would like to try it, I will save some seeds for you.

I cut off 'Goldsturm' spent blooms because I don't want anymore 'Goldsturm' in my garden, but leave R. hirta alone until the seedheads are completely dry, they I snap them off and spread them all over my garden. Their bright face always cheers me up every summer.

Funny you should say that goldfinches would eat green Echinacea seeds, debarron. I just saw a little yellow finch fly off my full bloom Echinacea yesterday. I didn't realize they would eat fresh seeds. I never had any Echinacea seeds to spread around anyway because goldfinches do the job for me. I have Echinacea seedlings coming up everywhere in my garden. 
    Bookmark   August 5, 2014 at 2:40PM
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riversurf

Thanks pitimpinai. I will look into triloba. My space is very limited, and not "officially" full sun, though most of the full-sun plants I have do reasonably well. My most fortunate find a couple of years ago was Rudbeckia fulgida var. speciosa Viette's Little Suzy, which grows 12-16" high. Perfect size for my little space and which allows me a little more variety that the full-size Rudibeckia's take up. I'm slowly phasing out my few big ones for this little beauty.

    Bookmark   August 5, 2014 at 3:27PM
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dbarron(z7_Arkansas)

Rudbeckia triloba is a denizen of the moist shady areas...they like sun, but usually don't grow in more than half sun.
I also heartily recommend it as a workhorse...though you must readjust your mind..the flowers are small, but many.

In great native habitat, triloba sometimes reaches 6 1/2 feet, but more avg is 2 1/2 or so.

    Bookmark   August 5, 2014 at 5:01PM
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