Which North American pines can be decandled?

[Gabler]

Is there a definitive list of which North American pine species are single flush and which are double-flush? I was reading a thread here which claimed loblolly pines are double-flush, which would be really handy for reducing those huge needles and thick branches. Another thread placed Virginia pine in the same category. That makes sense, since both are southern, coastal species like the Japanese Black Pine. I can't find a consensus on eastern white pine. I would assume that because they're a mountain pine, they're a single flush species like the white pine, but they have a pretty wide range, and they grow naturally in more coastal areas, also. Any direction at all would be helpful. Thanks in advance.

 

[Wires_Guy_wires]

As far as I've heard, it's those two and some varieties of rigida if treated a certain way.
I'm pretty sure EWP (p. strobus) is a single flush. But that depends on how you define flushes; if you cut the buds off in early or late spring, they will produce a new one. I haven't been able to get them to double flush like JRP/JBP.

Scots pine for example can double flush if you cut the shoots in june, but on the long run it'll weaken them substantially. So it kind of depends how you define double flushing.

To me it means practicing techniques to make pines produce full shoots twice a year without negatively affecting growth.

 

[PA_Penjing]

I don't want to spread lies but I believe Vance Hanna says he treats EWP as a double flush pine, and his strobus is the best I've ever seen, by more than a little. BUT fact check me on that one. Virginia pine definitely are, pitch pine definitely are, and if you look through the archives on this site you'll find that Loblolly are as well. Loblolly will "push" 3 to 5 rounds of growth/candle extensions a year depending on how long your growing season is. They are unique in that way, as far as pines I have owned, so I imagine that there must be some art/science to managaing their growth. I spoke to A very taleneted artist (nameless on purpose) once about his loblolly pines and he told me that they seemed to lose vigour with decandling and he had given up working on them in favor of vriginia pine. Maybe you can figure out who I'm talking about. But that's my list..

EWP - (pretty sure) double flush
Virginia - double flush
Pitch - double flush
Loblolly - double flush but need more research?
Jack pine - single flush IN MY LIMITED EXPERIENCE

I will do this entire thread a favor and NOT speculate about trees I haven't worked with, because assumptions can be dead wrong and waste years of our time. Always fun when someone experiments and gives us a new nugget

 

[PA_Penjing]

Couldn't resist, fact checked myself. EWP is double flush if you want a National Show worthy tree.

https://www.bonsainut.com/threads/ewp-pinus-strobus-at-fall-after-shedding-needles.46786/

 

[ShadyStump]

I should start a spreadsheet of all these sometime. But that would take time.
If it's not too rude, since we're on the subject, does anyone know about pinus edulis- two needle pinyon pines? They don't really make candles- just little buds- but from what I've observed in the wild they're single flush, but may readily pop a second flush if buds are trimmed early enough and the tree is healthy. There's a pamphlet out from the Rocky Mountain Bonsai Association that's very informative, but I've misplaced my download and can't find it online again.

 

[Gabler]

As I understand it, most pines can be decandled once, and in a healthy enough tree, it'll produce a second flush of growth without killing the tree, but only certain species are equipped to handle decandling every spring without leaving the tree progressively weaker each year. Given that information, I would hazard a guess that in optimal growing conditions, eastern white pine and loblolly pine can handle regular decandling and reliably produce a second flush of growth. In other words, decandling works if you don't compound the degree to which the tree is weakened with other factors.

 

[ShadyStump]

Thanks
That was my understanding, but pinyons have so little horticulture recorded it's hard to pass up any shot at gaining a little tidbit of info.
That and I know they're one of the few pines that will backbud, sometimes even in old wood. I've seen wild specimens with new needles budding from mature trunks! When that's the case, you always ask questions.

 

[PA_Penjing]

As I understand it, most pines can be decandled once, and in a healthy enough tree, it'll produce a second flush of growth without killing the tree, but only certain species are equipped to handle decandling every spring without leaving the tree progressively weaker each year. Given that information, I would hazard a guess that in optimal growing conditions, eastern white pine and loblolly pine can handle regular decandling and reliably produce a second flush of growth. In other words, decandling works if you don't compound the degree to which the tree is weakened with other factors.

That's exactly correct, I believe even JWP can be decandled, if that's your thing. But it's not good for the tree or sustainable. That's why I was careful to mention that each tree will have subtlties that need to be considered, but there's not much to refer to currently. So, we tend to treat our pines like JBP or JWP. Crazy to think about how much more we'll know in 30 to 50 years. I don't pay much attention to Ryan Neil's Pine videos because he works with different species than me, but he may have some insight on lodgepole, Ponderosa, flexilis and albicaulis.

Also VERY important to remember that "double flush" is different than pushing candles a couple times in a growing season. A scots pine might push candles twice a year if fed heavily, that's not double flushing. A loblolly may push candles 4 times in a season, that's not a quadrupel flush pine. "double flush" means that it can reliably have the candles removed and produce new finer growth. I did not know that my first few years in the hobby and it can make things confusing

@ShadyStump a fellow hobbyist, whom I won't see again until January has an edulis (it's a beaut) I'll ask him how he treats his. He's very talented but only a few years in so it may be the case that he hasn't experimented much with it yet.

 

[johng]

In my experience lobolly can certainly be treated with double flush techniques. I think the one issue that this conversation is lacking is that all pines are weakened over time with double flush pruning...some are just more vigorous and handle it better than others. The process of double flush pruning weakens the tree by design....we just call it "balancing the growth." Else wise, why would you see the pinus experts occasionally giving even JBP a break from summer pruning. In my experience all highly developed bonsai need a break from time to time...a period to just recover and get strong again.

 

[sorce]

know about pinus edulis- two needle pinyon pines?

I'd ask @PiñonJ , passion plus Mirai equals answers.

Sorce

 

[Gabler]

In my experience lobolly can certainly be treated with double flush techniques. I think the one issue that this conversation is lacking is that all pines are weakened over time with double flush pruning...some are just more vigorous and handle it better than others. The process of double flush pruning weakens the tree by design....we just call it "balancing the growth." Else wise, why would you see the pinus experts occasionally giving even JBP a break from summer pruning. In my experience all highly developed bonsai need a break from time to time...a period to just recover and get strong again.

So in other words, it's a spectrum of the degree to which decandling weakens the tree?

 

[PiñonJ]

does anyone know about pinus edulis- two needle pinyon pines?

They are slow growers in harsh, often semi-arid growing conditions, so they don’t fit the profile of a multi-flush pine.

They don't really make candles- just little buds

They absolutely make candles, but certainly not as long as fast-growing pines, or pines with longer needles.

Wild trees often push adventitious buds with juvenile growth, but that doesn’t make them multi-flush. Ryan Neil is treating them as one of what he calls “outlier pines,” which include Austrian Black Pine and Pinus pinea and halapensis. For these, he will de-candle as a technique to stimulate back-budding, not to reliably produce a second flush. And he’ll only do it once, or rarely. However, I’d say these techniques are still evolving, because he has far more experience with other species. The good thing is, he’s always experimenting, so we should get more information in the next few years. I have a Piñon I purchased from Todd Schafer that I want to repot in the spring, so I won’t do any foliage work until the following year.

 

[0soyoung]

So in other words, it's a spectrum of the degree to which decandling weakens the tree?

You can substitute the word 'pruning' for 'decandling' and it is a more powerful/useful statement of horticultural principle.

 

[Leo in N E Illinois]

An important factor.
Climate
Climate
your local micro-climate is everything.

I live inside the "Lake Effect" band of Lake Michigan. My spring is often dominated by cool east winds, which will keep my daytime highs from March through May seriously chilled, some 10 to 20 degrees F cooler than a few miles west of me. So in early May, the official Chicago temperature at the airport ORD might be 75 or 80 F, I will have 50 to 60 F at my home. Japanese Black Pines need heat to wake up in spring. I often do not get candles developing until June and July, even though the trees have been out since May 1. For decandling to work, you candle prune 100 days or more before your average first frost. My first frost is around Oct 1 to Oct 15, this means I do not have sufficient time for my JBP to develop new candles if my JBP do not "wake up" until middle of June. So often in my climate JBP MUST be treated as a single flush pine, even though in theory they are a double flush pine.

Eastern white pine (Pinus strobus) and Japanese white pines are single flush pines in my experience. The Japanese white pine, is the "architype" of single flush pines. It is the techniques developed by the Japanese for JWP that set the standard for how to treat a single flush pine. It is fairly safe to assume that all members of the subgenus Strobus (the white pine subgroup of pines) are all singe flush pines. There may be a few exceptions, but it is a safe bet to treat all members of the white pine group as single flush pines. These may push adventitious buds and occasional needle buds over the growing season, but this does not make them "true" double flush pines.

Jack pine, Pinus banksiana is definitely a single flush pine in my experience. I have had a few adventitious buds pop over the summer, but never enough, and never reliable enough to consider a double flush pine. Jack pine is strictly a single flush pine.

I have no experience with Pinus rigida, I have a few young seedlings, too young to count as experience with their flushing pattern. However, everything I read suggests that pitch pine, P. rigida, will be a double flush pine in a long summer climate, zone 6b or 7 and warmer. Time will tell whether they will be "double flush" in my climate, zone 5b. Climate is critical in determining whether single or double flush pine techniques can be used.

 

[Gabler]

So when in doubt, just treat a pine as single flush and take your time developing and refining it?

 

[0soyoung]

So when in doubt, just treat a pine as single flush and take your time developing and refining it?

Indeed!


But, you can always experiment on a branch or two to see how it responds. What you do to one largely has no effect on the others.

 

[ShadyStump]

They are slow growers in harsh, often semi-arid growing conditions, so they don’t fit the profile of a multi-flush pine.

They absolutely make candles, but certainly not as long as fast-growing pines, or pines with longer needles.

Wild trees often push adventitious buds with juvenile growth, but that doesn’t make them multi-flush. Ryan Neil is treating them as one of what he calls “outlier pines,” which include Austrian Black Pine and Pinus pinea and halapensis. For these, he will de-candle as a technique to stimulate back-budding, not to reliably produce a second flush. And he’ll only do it once, or rarely. However, I’d say these techniques are still evolving, because he has far more experience with other species. The good thing is, he’s always experimenting, so we should get more information in the next few years. I have a Piñon I purchased from Todd Schafer that I want to repot in the spring, so I won’t do any foliage work until the following year.

Thanks! This is generally in line with what little working theory I already have, but you're helping filling in some gaps. I've had awful luck collecting in my area just because the geology essentially demands bare rooting when you dig them up, so if this latest one survives (still looks happy so far) I don't want to just go and kill it anyway by handling it wrong. Every tid bit helps!