Dahlia Season: Plant, Support, Irrigate & Groom forum: Topping and Limiting Lateral

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Jun 10, 2015 10:50 AM CST
Name: Ted
We enjoy breeding new dahlias!
Our PNW Gal did a presentation on topping and plant control at the Portland Dahlia Club meeting. Lots of interesting material. One club member said that when he grows giant dahlias, he does not limit the laterals immediately. He tops the plants at 4 or 5 laterals and then allows the plant to grow a bit and then removes the weakest laterals later to get to the number he likes(that is 4 while many people do 2). He like the 4 laterals as he gets more flowers from the giants and he delays the blooming on 2 of them by pinching off buds.
We like to place a sign on our porch that says: We are in the garden. Really, we are always in the garden.
Jun 10, 2015 12:25 PM CST
Southern PA, Brandywine
Our deer are doing my topping off for me this year. Blinking Angry
Jun 10, 2015 12:32 PM CST
Name: Darcy D
Green Oaks, Illinois
Uh oh. Hopefully they are at least getting it at the 3-5 lateral spot ;)

We are lucky, although there are loads of deer around here....we aren't on their path from preserve to preserve. An elderly neighbor told me we used to be, but then they did some new construction and it changed their path so they don't cut through here any more.
Jun 10, 2015 1:34 PM CST
Name: CC
Four or five laterals = 2-3 leaf sets

Jun 10, 2015 4:26 PM CST
Name: Linda
Portland OR, zone 8b
Yes, 4-5 laterals = 2-3 leaf sets. He said that when he had tried topping the plant leaving only 1 set, sometimes it had not grown both laterals, and sometimes he got none at all. (I would think in that case that the tuber would send out a new shoot from the base, but you would be starting all over again.)

Many growers think it is wise to allow a few extra laterals to start, and then remove the ones not needed. This is called disbranching or debranching. As well as ensuring that there will be enough laterals, it also lets you select the best ones for vigor and placement.
Jun 10, 2015 10:27 PM CST
St. Paul, MN
I would agree with that method. Some things you read on restricting growth focus a lot on when to top. I find it more important to just determine how many laterals you want to grow. If you top an AA dahlia after just a couple sets of leaves; your laterals are very low to the ground. Sometimes that's ok; but I think it can be better to have them up a little higher. I'm more likely to wait to top a plant until I see a tiny terminal bud.

Then, I'll wait until the laterals are growing for a bit before choosing the strongest looking ones to keep. Typically the faster growing ones are the ones getting more light (but not always).
As a general rule, for dahlias that I really want to fuss over to get good blooms for shows; or catalog photos I will allow

AA- 2 laterals
A - 3 laterals
B- 4 laterals
BB - 5-6

Most everything else; I'll just top it when it has a terminal bud and let it bloom away. Usually, one or two laterals don't develop anyway so it kind of "restricts" itself.

For AA or A sized blooms, I'll be sure to choose laterals from different leaf pairs. Almost like a ladder. That way you usually only have one flower at a time.
Jul 29, 2016 4:29 PM CST
Name: Amanda
CA Redwood Coast - Zone 9b
Would anyone care to expound more on what to do after the first flush of blooms? I pinch out the center when the plant is about a foot high. The top three laterals produce lovely blooms, but the next in succession sometimes produce flowers that are only 2/3 the size. I like big flowers. Do I need to remove all but the most advanced three until they are done blooming and only then let other branches grow?

I don't know. Honnat has probably already answered this with the previous post. What I lack is resolve probably, more than knowledge. ;)
[Last edited Jul 29, 2016 4:32 PM CST]
Quote | Post #1209562 (7)
Jul 29, 2016 5:50 PM CST
Name: Cynthia
BG, KY USDA Zone 6b
Sanity = Dirt under your nails...
I hate pinching back, and definitely lack resolve. If I'd actually do it and see positive results, I'd be more motivated. As it is, everything seems to conspire against me until inertia sets in and another year goes by without me pinching back like I think I know I should... Rolling my eyes.


All gardening is landscape painting.
- William Kent

Aug 5, 2016 3:22 AM CST
I don't stop anything until at least 5 pairs of leaves, regardless of variety.
With giants, I'll let the 4 strongest laterals develop until they show buds. Then, depending on when I have a show, I'll remove one of the laterals and let the buds develop. So I tend to get 3 blooms on the same plant that are all ready within 5 days. If they are early, meaning they will be finished before my show, I'll remove the crown bud and grow off a wing bud. That will delay flowering by a good 2 weeks. They end up a little smaller, but definitely have better form. So this is Sir Alf Ramsey on a wing bud.

Thumb of 2016-08-05/scrumpy/087556

Growing off a wing bud, or a lower lateral below the buds, works for all varieties, meaning you can stagger your blooms on your plants so you don't have them all flowering at the same time. So a small variety that you are growing 8 up, by selecting a variety of crown buds, wing buds and lower laterals, you can easily have them flowering over a 2 week period. Don't choose number 2, you need a wing bad with a leaf below the bud. So number 1 wil flower first, number 3 a week later, number 4 2 weeks later.

Thumb of 2016-08-05/scrumpy/1bc6df

Sometimes when you are growing plants, when you stop them, you don't get the number of laterals you want. You may only get 4 develop, when you want 8. So what you do is do a " double stop". That means removing the growing point on each of the 4 laterals at the 3 leaf stage. New laterals then form, so where you had 4, now you have 8. When those grow, flower size won't be affected.
Aug 5, 2016 6:50 AM CST
St. Paul, MN
Good info. I had never heard wing buds tend to have better form Is that cause it's smaller or another reason.
Aug 5, 2016 11:00 PM CST
Name: Linda
Portland OR, zone 8b
Great photo. With the labels and the descriptions, I get what you mean by using wing buds. Before, I thought you meant the bud without leaves below it, and I wondered how you could get a straight stem out of it.
Jun 8, 2017 10:41 PM CST
Name: CC
"I really need to get out there and get them pinched back. So many are ready to bloom, I hate to do it. Maybe after the first bloom?" (quoted from Weather Chat)

The first bloom at the terminal tip of the plant acts the same as topping... the plants that are reluctant to put out side shoots often wait until the terminal bloom OR topping (pinching back) before doing so. Then again, there are lots of varieties that need no prompting from the grower's pinching fingers to grow lateral shoots, and topping only serves to keep the plant somewhat shorter then it otherwise would have been.

I let a couple of the first buds bloom to give me a 'fix,' and pinch out the others, as I find the first spring blooms to be typically disappointing, and I'd rather encourage the plant to use its energy into growing laterals over a spotty bloom.
Jun 9, 2017 9:38 AM CST
Name: Ted
We enjoy breeding new dahlias!
The height of the variety is important when topping or as they say "stopping" the plants. Dahlias that tend to grow very tall need to be encouraged to branch and need to be topped. Shorter varieties reach their terminal height(how do they know when to quit growing?) and start sending out laterals(big word for more branches). Why do want laterals? That is because the next blooms will form on those new branches. Remember it is not all that critical about how you limit dahlia height by topping. Swan Island uses a converted lawnmower to top their plants. Many growers do not spend much time stopping their dahlias and their gardens look fine. Cut flower growers effectively "top" their plants when they harvest the blooms, especially when they pick really long stems(technically stems and stalks as the stem extends only to the first set of leaves). Show growers have goals of limiting the number of blooms per plant to a perfect number depending on the size of the bloom. They want only two flowers on a giant(some enthusiasts want only one). Four is a good number for "B" sized flower and maybe 4 to 6 for "BB".

And there is some variability in dahlias concerning "overblooming". Some varieties produce too many flowers and the flowers become too small and the stems are weak. An example is the top winner Lakeview Glow. It is an overbloomer and has to be disbudded and disbranched to get show flowers. For cut flowers, overblooming may be a bad thing as flowers need good stems and overbloomers need to be disbudded to get the good flowers. Whether it is worth the effort is up the grower.
We like to place a sign on our porch that says: We are in the garden. Really, we are always in the garden.
[Last edited Jun 9, 2017 9:56 AM CST]
Quote | Post #1251032 (13)
Jun 15, 2017 12:25 PM CST
Stopping is not always about limiting laterals. It is also a way of increasing them. And increasing stem length. You basically use the double stop method. So if you have 6 laterals growing after the first stop, you stop each of those at the 3 leaf stage and then those 6 turn into at least 12 laterals. So for garden use, let them all grow and you'll end up with longer stems, but smaller flowers.For exhibition, you choose how many to grow. Just pick the laterals with buds on that will flower in time for your show, and remove the rest.

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