when to prune a butterfly bush?

gardenbug(8b)October 20, 2012

Do you prune a Butterfly bush back in the fall or wait until spring in the PNW? Thank you.

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jaco42(z5NEOhio)

Here in zone 5 ne Ohio I cut them back in spring just before they leaf out.

    Bookmark   October 21, 2012 at 2:12PM
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gardengal48

In our zone, Buddleia davidii is semi-evergreen. I'd make sure to deadhead it routinely if not one of the sterile cultivars and prune it back by 1/2 to 2/3 in spring. Buddleias tend to be rather weak wooded and some can grow quite large in our climate and are then subject to breakage and wind damage - even toppling in a wet, windy winter.

    Bookmark   October 21, 2012 at 3:52PM
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gardenbug(8b)

Thank you jaco and gardengal for your replies.

Gardengal, I've been deadheading my Buddleia all summer long and it had lots of blooms, except it wasn't very bushy and seemed kind of tall and gangly. It get's full sun. So, you are saying I should wait until spring to prune it back? It's about 6' tall right now. I just finished putting some mulch around it. Thanks again for your help.

    Bookmark   October 22, 2012 at 1:40PM
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gardengal48

"Tall and gangly" is pretty much SOP for a larger growing buddleia :-) They never look full and bushy. If that's the look you are going for, I'd consider sussing out one of the many dwarf or compact varieties on the market now. And many of these have the added bonus of being sterile, so no worries about constant deadheading or contributing to the invasive species issue.

Yes, I'd wait until spring to prune. Fall is not a recommended time of year for any woody plant and in our climate, still leaves plenty of opportunity for the plant to push new growth, which can then be an issue for cold damage when temperatures may plummet later in winter.

    Bookmark   October 23, 2012 at 2:29PM
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gardenbug(8b)

Thanks gardengal. I'll wait until spring to prune it back.

    Bookmark   October 24, 2012 at 12:41PM
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Tiffany, purpleinopp GardenWeb, Z8b Opp, AL

Totally agree with the pruning advice.

But there's no reason why your plant shouldn't be full and bushy next year if you guide the growth through pinching and pruning. BB's need at least bi-weekly attention or they will become their stereotype, too tall, sparse, gangly, full of brown seed heads and tiny bare twigs.

When you do prune in the spring, and throughout early summer, stick any of the live trimmings you like into the soil or a pot and they should grow as long as they are not allowed to desiccate before they can make roots. Since they're prone to suddenly dying, I try to keep several around.

GG, I respect the excellent advice I see from you in these forums, and admire the generous spirit in which it is offered. And in the spirit of genuine curiosity with no snark intended... I notice that you almost always warn about this plant as being invasive yet I've often seen you encourage/defend Hedera helix and Vinca. Do you not consider those plants much more likely to grow beyond a gardener's control than a BB? Aren't they more likely to enter a natural ecosystem than Buddleia? My Mom can't be bothered to deadhead her BB's, but I've never seen a baby sprouting. I've never been to your part of the country, and am honestly asking. I've never seen a wild BB on this side of the Rockies, although I admit this would be a difficult plant to spot from a moving car, or a hike through the woods outside of the blooming season. Also recognize that people just like certain plants more than others and therefore rationalizations can be more powerful. We all have those.

Similarly, what natives might be used instead that would be a comparable nectar source as BB - blooming for 7-8 months? BB seems worthy of invasion to me, but am open to further info, and really am curious what you and anyone else might think and have experienced...

    Bookmark   October 24, 2012 at 12:46PM
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gardengal48

Purple, I will warn about any plant I know to be invasive in my area (zone 8, Pacific Northwest, especially the Puget Sound area). A good number of plant species that are invasive in other parts of the country have not (yet) proven to be so here. And vice versa. Some - like Buddleia - have been found to be very problematic here but not so much elsewhere. Invasiveness is very regionally oriented :-)

And while I have defended Vinca minor (not V. major) as not being a particularly invasive species in my area, I do caution against planting it close to any natural or wooded area because it can and will spread. But it is not to the point of it being considered a noxious weed or a listed invasive species. OTOH, I defy anyone to find where I have ever, ever defended Hedera helix on any of these forums. I won't even recommend this plant in areas where it is not considered to be particularly invasive (typically only those areas cold enough to kill it back in winter!!) because it provides an excellent habitat for all manner of vermin. And in the PNW, this plant is perhaps the most pervasive invasive plant problem we deal with. And it is everywhere.

Buddleia davidii is an especially prolific and fertile seeder. Each flower head can contain as much as 40,000 seeds and with an 80% germination viability. That's a whole lotta potential butterfly bushes!! And you do see them growing wild in my area - in the cracks of abandoned parking lots, in vacant lots, along railroad tracks and the sides of the road and freeway verges. And most disturbing are the large colonies of these shrubs found along streamsides and cleared areas throughout western Washington and Oregon. They outcompete native habitat, in particular our native shrub willows, which are the preferred habitat for our native butterfly species.

I'm not saying BB is invasive everywhere - again, with any invasive species it is location, location, location! However I know specifically where Cadence is located, which just north of my own location, and plants which are invasive here will also tend to be invasive there.

As part of a consumer awareness program sponsored by our state invasive species council, the regional professional landscape and nursery association and a consortium of local retail nurseries, a publication recommending alternate suggestions for invasive plants has been made available. Substitutes for BB include west coast natives Ceanothus and Pacific ninebark as well as chaste tree. And of course, the new sterile BB cultivars recently introduced to the consumer market.

Here is a link that might be useful: Butterfly bush in western WA

    Bookmark   October 24, 2012 at 4:09PM
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Tiffany, purpleinopp GardenWeb, Z8b Opp, AL

Thanks for the detailed and informative reply. Always interesting to note how different the same zone can be!

Your link mentioned that these seeds need exposure to germinate, which would explain why a garden that gets covered in leaves every fall wouldn't see seedlings.

Must have you confused with someone else on the ivy, hope you'll please excuse my apparently false memory!

Never seen a Ceanothus in person, wonder if they don't like really high temps? For years I've been in love with pics of them though. Vitex blooms for a much shorter time compared to BB, same thing for Physocarpus. Between the two, there could be blooms for about 3 months, if the links I consulted for Physocarpus are accurate. There's enough Vitex around that I recognize to know when it blooms.

What is the botanical name of the plant you're calling shrub willow?

    Bookmark   October 25, 2012 at 3:45PM
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gardengal48

Purple, it's a common misconception that seedlings of invasive species will necessarily pop up in the same garden in which they are planted :-) Often, just our routine cultivation and mulching practices will put paid to that notion. This should never be used as any sort of guideline for invasiveness in your area as it is just a not a reliable indicator. With the BB, seeds are disbursed by wind - each seed actually has wings that allow it to float a great distance. The seeds are also favored by certain bird species, who contribute to the dispersal as well :-) FWIW, buddleia only blooms around 3 months here - late June/early July to about now.

Ceanothus native to the west coast are somewhat picky as to their conditions - heat not an issue but humidity certainly would be a limiting factor. Otherwise, they require lean, well-draining soil, no fertilizing and no summer irrigation. There are some east coast species too but not sure any would be happy in the south ;-) I'm not sure any of those are evergreen, either.

The shrub willows are of the genus Salix. There are some 31 species native to the Pacific Northwest and help to create a habitat for native bird and insect species.

No worries about the ivy - just don't want anyone to mistakenly think I would promote that plant for anything other than rather limited container applications. And only then with the so-called fancy-leaf forms that are less robust in growth habit. Not a nice plant in the ground under pretty much any circumstance.

    Bookmark   October 25, 2012 at 4:59PM
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Tiffany, purpleinopp GardenWeb, Z8b Opp, AL

Thanks, I wasn't asking how invasiveness works, or using our personal experience as a gauge, which is why I mentioned never having seen one in an uncultivated spot, just curious why I've never seen a seedling over a couple decades of growing these shrubs. Obviously it's a culture issue if there are seeds being produced, I just didn't know what to attribute it to. Your comment about certain bird species makes me wonder if the birds on this side of the country just don't find these seeds as yummy, nobody's mulching wild areas.

Ahh, humidity would explain the lack of Ceanothus here... and sometimes I wish it also indicated a lack of people, especially me! Whew - air you can wear! That's a shame the beautiful Ceanothus can't abide it, and I hope folks will continue to take wonderful pics of these beauties!

I know there are butterflies that use various Salix as host plants but would like to know more about them as nectar sources. I definitely don't know 31 species but thought they were early spring bloomers in general. Probably an exercise on par with learning more about Ceanothus though, the ones you know would probably be unhappy here, especially during really dry summers. I always think water-lover when willow's the topic.

I'm under the impression that it's not as sunny there in the winter, and doesn't warm up as quickly but have never been west of TX. It can start getting into the 80's by late Feb here in LA (lower Alabama.) Do you think that may be why the BB's are able to get an earlier start? They're still going strong today with plenty of unopened buds still, tons of gulf fritillaries still visiting them.

Wishing us both an ivy-free day! Sorry about that.

    Bookmark   October 26, 2012 at 10:34AM
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flora_uk(SW UK 8/9)

Buddleja is a pain here too. I eventually killed a huge swathe of Japanese Knotweed off and the species which blew straight in to the empty space was Buddleja. Miles from any deliberate plantings of it.

    Bookmark   October 26, 2012 at 2:16PM
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yugoslava

I have never heard of buddliea being invasive. At least not in Toronto, Canada. However, in different zones it might be. Butterfly shrubs should not be cut in the fall. If they are they may not survive winter.

    Bookmark   October 31, 2012 at 10:56PM
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rouge21_gw(5)

I have never heard of buddliea being invasive. At least not in Toronto, Canada.

That's for sure. It is hard enough getting them to over winter in a climate like that of Toronto Ontario!

    Bookmark   November 2, 2012 at 2:14PM
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Embothrium(USDA 8 Sunset 5 WA)

Like hybrid rose bushes, butterfly bush is typically starting to grow here in February.

    Bookmark   November 2, 2012 at 5:31PM
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katob Z6ish, NE Pa

Not to beat a dead horse, but buddleia really is far more invasive in the PNW. Like GG already said, in some areas it is almost the only thing you see lining the side of roads for miles. Hard to picture when here all you get is one or two seedlings a year.

    Bookmark   November 3, 2012 at 9:49PM
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