I would say that 75% of our Single Stem Prestige Reds have split within the last week. Is anyone else experiencing this?

The plants were potted June 15th, are 17 inches tall on average, planted in 8 inch pots, have not been given PGRs, have had all suckers pulled, and have strong growth aside from the split. I pinched off two of the 3 shoots.

Is this going to throw the plants off schedule dramatically?

Thanks folks.

Hi Adam -

We haven't heard from anyone else that splitting has been a problem - let's see if anyone comes back with comments.

Are these straight up plants or are they pinched?

Thanks!

The plants are single stem, no pinch. I believe it has something to do with a couple cool nights we have a week ago, although it didn't get below 65. Like I mentioned earlier, 75% of Prestige Red, and the closer I looked, about 40 percent of the Freedom Pinks. All are scheduled to be displayed at the end of November at a height of 30 inches +/-.

Hi Adam -

We should talk about the various reasons for splitting to try and determine why your plants split.

Splitting occurs when a single flower develops in the terminal but fails to develop. Three lateral shoots develop from the terminal flower.

Flowers can be initiated even under long days. The probability of initiation becomes greater under long days as the number of leaves increases on non-pinched stems. The long day leaf number refers to the number of leaves poinsettias produce before a terminal flower develops even under long days. Most cultivars on the market today have a long day leaf number in the 30's. Some older cultivars that are susceptible to splitting have a long day leaf number of only 12-15. Prestige and Freedom both have long day leaf numbers in the 30's though Freedom is more susceptible to splitting so we usually don't recommend it be grown for trees.

We usually see splitting on cuttings taken from over mature stock plants or plants that have high leaf counts because of infrequent harvesting. This is because cuttings don't forget their leaf number so on plants that aren't pinch they may reach their long day number and split as a result.

You mentioned some cool nights. Night temps below 60F (15C) can cause splitting; 65F is not cool enough to be the probable reason for splitting.

Splitting can also occur if the plants are placed in a short day environment for flower initiation than they are taken out of the short days and placed in long days again. This can be the case on stock plants that aren't lit but you would have seen the split a long time ago if this were the case.

Of these three scenarios it is most likely that the plants reached their long day leaf number because they weren't pinched.

Do you grow your own stock? If not, where did you source the cuttings?

It is hard to say for sure at this point what the plants will do. Sometimes once the split has occured vegetative growth stops. Since you pinched out two of the shoots the third shoot will take over dominance but it is hard to say whether or not it will initiate again. Since you pinched out the two shoots you may also see some lower later shoots start to form.

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