The Long Range Plan for Single-flush Plants ~
Decandling black pines…defoliating trident maples…such techniques stimulate multiple flush plants to ramify and make smaller needles and leaves. Because they spur such surprising regrowth, we look mournfully at our single flush plants as if they could do better.
White pines, Japanese maple, Beech, Spruce, Hemlock, Magnolia, Oak, etc. all fall into the single flush plant category. And we need to play the long game with these once-a-year growers.
Mountain Hemlock, a single flush plant. (Photos here link to styling / creation stories.)
5 years later. Ramification of this genus is fairly easy as many buds arise from each spring shoot. In a short amount of time shoot multiples need to be trimmed annually to make room for next year’s crop. The next two examples are trickier to ramify.
Because single flush plants won’t respond to wholesale mid-season removal of spring growth, expecting regrowth, we need sneakier ideas. Our goal is the same for all bonsai, though: more twig ramification and smaller needles and leaves. How do we do that if we can’t defoliate or decandle?
- Work on getting budding…
- More budding brings more shoots…
- More shoots brings down leaf and needle size quite naturally
Bringing more budding on single flush plants is by nudging rather than forcing, and time. Pruning timing helps. If you prune in springtime you’ll get more extension; if you prune in early fall, you’ll get more budding. Those buds will turn into shoots come spring, and the more shoots you leave, the shorter future ones will become. Later cut off the longer ones.
An example: A pine will often create 3 or more shoots from one shoot end. If you have a thin pine, with few shoots, maybe leave these multiples one or two years. They will help slow down the rest of the tree, then later cut off the longer ones. The rule ‘cut everything to two’ isn’t wrong, but can be delayed for good effect in the case of thinly foliaged single flush plants.
Limber Pine—a single flush pine.
4 years later. With good sun and grown moderately, Limber Pine buds and ramifies rather well. But the roots haven’t filled out the pot, so the needles remain longish. In a few more years these will come out shorter in length.
Young single flush plants often respond the way multiple flush plants do. A good example is Japanese Maple. Cut a 5 year old Japanese Maple hard, or defoliate it after the first flush has hardened off, and it will likely reflush. Completely defoliate a 50 year old plant and there’s no telling how it will respond. In maturity, Japanese maples are single flush plants—they are programmed to grow once a year.
Age plays another role in internode length, which translates to density. A young maple will grow hard without much encouragement for 10-15 years. Those can be frustrating years if we’re doing everything we can to slow it down and the internodes are still miles long. Then it begins to brake—without us changing any horticultural practices. My suggestion is, don’t fight the youthful energy, use it. Develop trunks and branches in those years, then later when age is working with us we can more easily shorten internodes.
Vine Maple—a single flush deciduous tree similar to Japanese Maple. This photo is from when the composition was first assembled. The growth is sparse, and several branches were left on that are not ultimately desired. The twigs are also thin and delicate from living a spare life in the wild, and it may take 10 years to achieve that delicacy again after the invigorating, youth-inducing techniques of bonsai creation.
5 years later. By keeping multiples of things that aren’t ultimately wanted, all the shoots get shorter. Then the long ones are cut off. Ramification of this tree has quadrupled in 5 years using this method. But you can still see some long internodes, it’s still a work in progress. Short shoots are also helped by the root mass getting denser. With a multiple flush plant we could get there a lot faster, but an old Vine Maple doesn’t offer the defoliation option.
Why talk about plans for single flush trees now, in spring? So we know how hard we’ll grow our plants and what we’re going to do next. With a single flush tree we can fertilize less, or maybe not at all until growth has hardened off. Fertilize single flush plants more in the summer and fall. But that’s for a well-ramified tree.
In the developmental period, with thinly foliaged trees, don’t worry about large leaves or needles on your single flush plants. Short leaves and needles are for older bonsai, with well-stocked IRA’s, tertiary investments and such. Have a thinly-twigged Lodgepole pine with long needles? A Stewartia with large leaves? No worries. Large leaves and long needles make more buds. Those buds will create shoots, and with more shoots, needles or leaves reduce without any further assistance, and we’ll begin look at our single flush plants less mournfully.
Hey Mike – so you mention for well ramified plants fertilize in the summer and fall. For less well ramified plants, should we fertilize in the spring as well, before growth has hardened?
Hi, light fertilizing in spring is ok for many single flush plants, when thinly twigged, yes. (With double flush plants it’s nearly the opposite, strong fertilizing in the spring, less later in the year.)
Thanks – if I’m working with spruce is this before buds have opened, as they open, or after they’ve opened?
If a spruce has few shoots on it, a light fertilizing as the buds are opening is not a bad policy. This will create larger, stronger structures that ultimately lead to more budding.
Great post Michael, good reminders that trees need time
That’s just what we discovered with our American beech. If we do pruning around September here in Dallas TX they bud back well, but if done in spring, less back budding and these buds often wait a year to open. So odd!
Beech is a good example— and it’s really hormonal. If you cut in fall the plant has all fall for cytokinins to create buds, but in spring the plant will usually grow with the buds it had already set from last fall.
Single flush plants? Please give me a definition.
Sure, single flush plants are once-a-year growers. Multiple flush plants grow two or more times a year.
Really helpful article, Tx much
Hi, I tough Japanese maples were multiple flush plants, although I don’t tend to prune them often how can one explain the ‘hedge pruning technique’? Which it is used by some on mature trees. Thank you.
Hi Paolo, Trident maples are multiple flush plants, Japanese maples are single flush. Old trees we’re talking about, though. Any sort of strong, overall pruning will make even an old plant reflush, but that’s where we see the difference in a plant that doesn’t have a problem reflushing consistently—like a Trident—and one that will reluctantly do so, like a Japanese maple, and often throw out misshapen leaves in the reflush. Any sort of strong pruning mid-season will also tend to keep trees younger. Mild pruning, reinvigorate. No pruning at any time of the year, and plants will get senile and begin losing branches. So…some pruning of both multiple flush and single flush plants is necessary, but how much we do determines the functional age of the plant. Which isn’t an easy balance, I find.
My young Japanese Maples act like multiple flush trees right now. So, as you say, I will use this to my advantage. When I let the tops, leader, grow out on these trees, it seems to let me keep this multiple flush-like character longer as they age. Any thoughts on this?….your experience?
Hi Steve, yes—correct— those trees with a strong leader growing off the top to thicken or change direction of the trunk will tend to keep plants younger than their actual age. In a tree, age is a fluid concept. My teacher’s teacher (Hamano) said if you cut an old bonsai hard you’ve just made it 40 years younger. It’s a generalization, but if we see that in reverse… by growing a young plant hard and letting something escape and then periodically whacking that off to change direction of the trunk (in early development), then we keep a perpetual fountain of youth going. Keeping, and using, the multiple flush characteristic of a young single flush plant.
Hi Michael, Do I understand that if i’m trying to get back budding on some weak spruce I should not pinch in the spring but wait until fall to cut this years growth back?
Hi Bill, yes you have the idea. A weak tree should be left to grow through the growing season. Then, come fall, determine how strong it is. Perhaps even then it shouldn’t be cut, if still weak. Once strong, pinching in the spring can be an effective technique to create buds down the shoot. And also fall pruning, back to inner growth.
Hi Michael, my question here is about defoliation of Japanese maple. How does partial defoliation of mature Japanese maple cause secondary budding if they are single flush. I can understand the concept of full defoliation causing a new “spring” but partial defoliation seems to stimulate new buds as well. Or is this just a case that my maples are not mature enough to have reached the “single flush” stage?
A great question Peter— you’re right, partial defoliation, a common Japanese Maple technique, does stimulate some budding on the interior and strengthens smaller buds already present. But ‘flush’ is the key word. Those buds won’t generally pop and open into leaves until the next spring. We see the same potential in a single flush pine, like a Japanese white pine or Lodgepole pine. If you cut the candles completely off in late spring (as you would with a black pine, expecting new candles), you will get buds but those buds won’t open. They’ll open the next spring. That is—on an older tree. If you’re doing partial defoliation on a Japanese maple and it’s reflushing, it’s either a young plant or in a youthful mood or has a high amount of fertilizer… which underlines the grey zone of claiming anything as wholly single or multiple flush. They are all subject to their environments. A Black pine without enough sun after decandling may not grow out new shoots that year. The lack of sun may limit its natural energy.
Hey Michael, thank-you for the great reply. I need to look at more of my trees as individuals, not like a monoculture tree farm.
I’m still very confused!
We have a relatively strong Mugo and we want to create back budding. The interior is bare.
Do we wait till fall to trim this year’s growth? i.e. don’t remove or trim this year’s candles in the spring.
Hi Andrew, it is confusing! There are a lot of variables here. This article is general, and then we break down into differences according to genus and species which other blog posts attempt to cover.
Depending on what you have there with the Mugo, if interior branching is desired where the branch is older, then grafting may be the only way to get it. Wiring your tree and bringing branches down can also help budding closer in. Pinching spring shoots may help back budding. Spring pinching and fall pruning are your main techniques for getting back budding on single flush pines, though all our efforts may result in minimal back budding per year in even ideal situations.
Try this blog post about pinching pines:
Hello Mike, thanks for an eye opener on faster development of younger trees into something that will look more like a bonsai.
Glad it was of service!
Mike, I need your help. Is boxwood single, or multi-flush? And quince? Thanks.
Hi, boxwood is generally single flush but every year or two they can be encouraged into a second flush. I would not try this every year on a mature plant as they can tire out. General maintenance, though, consider it as a single flush plant. Any strong quince is a fully or semi-multiple flush plant. That is, if you cut back the spring shoots after they harden off, usually you get a partial push again.
Thank you very much Michael. After this blog (and reading it a few times to digest new information) I’m revising my pruning plans for the future.
Glad to hear! Cheers-