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Tuesday, December 6, 2011

Pinching of 'Lord Baltimore' Hibiscus


The above photo was taken immediately after the second pinching on 6/7/11.

'Lord Baltimore' hibiscus is a big and fast growing hardy hibiscus with indeterminate growth.  It has very large, dramatic, single dark red blossoms.  It is sterile and does not form seed pods after it blooms.  This helps to keep it blooming up until the time that frost first hits.

Under good growing conditions in late spring and early summer, 'Lord Baltimore' may grow so fast that it's stems do not have time to develope enough strength to hold themselves upright.  The stems rarely branch and the resulting appearance can be quite open and gangly.  Pinching the new growth back in a timely manner can help reduce both of these problems and create a much more attractive plant with many more stems and blooms.  Pinching or heading back the shoots is best accomplished with a quality bypass hand pruner.
    
The plant in the photo above was first pinched on 5/23/11 and received its second and final pinching on 6/7/11.  The first pinch was made when that the shoots were between 26 and 35 inches long.  About 11 inches was removed.  The second pinch was made when that the shoots were between 39 and 47 inches long.  About 11 inches was removed.
    
The blooms may be delayed somewhat by pinching; however, under favorable growing conditions, 'Lord Baltimore' will still get 6 feet tall by 12 feet wide by early fall.  The 'Lord Baltimore' Hibiscus that received the two pinchings described above started blooming on 7/7/11.  The last picture below shows a 'Lord Baltimore' Hibiscus plant with 50 open flowers on July 26, 2011 after two earlier pinchings.  The blooms are somewhat smaller when you have this many flowers open at once; however, I feel that the plant is much more attractive.


July 12, 2012 update to the above article:  We had an unusually warm winter and spring this year which contributed to earlier growth and flowering than in 2011.  This year, after two pinchings, 'Lord Baltimore' Hibiscus had its peak or maximum number of blooms open on July 10, 2012 with over 40 blossoms open per plant.  This is 16 days earlier than the peak or maximum number of blooms open in one day for 2011.  This is the same date that another cultivar, 'Sweet Caroline' Hibiscus that was not pinched, reached its peak or maximum number of blooms open in one day.  


Above: In late October after leaves had dropped, it is very easy to see where that the pinching or heading back cut was made.


Above: July 13 blooms after one pinching in late May.


Above: July 13 blooms after one pinching in late May.


Above: July 13 blooms after one pinching in late May.


Above: July 10 blooms after two pinchings as described in the article above.


Above: July 26, this 'Lord Baltimore' Hibiscus plant had 50 blossoms open on this date after two earlier pinchings.

More information on 'Lord Baltimore' Hibiscus: http://www.arboretum.umd.edu/bloom/archive/featuredPlant03.html

author, Sam Bahr 

7 comments:

  1. Sam, isnt "Lord Baltimore" a dinner plate size Hibiscus? I had one planted, and it got scraggly, but it didn't come back the next year. Should I have pinched it back, and by pinching how far from the leaf branch are you clipping?

    ReplyDelete
  2. Debi, the flowers on 'Lord Baltimore' can certainly be dinner plate size if you provide favorable growing condition. If your interest is in producing flowers as large as possible, you should not pinch back your hibiscus plant at all as I described in this article. Pinching in the way that I outlined reduces the size of the flowers, but produces more of them.

    Hardy Hibiscus in the wild are often found at the edges of streams and rivers where that the soils are moist. They will not do well in dry soil conditions unless provided additional water so that they do not dry out. While in general they are relatively disease resistant, I have seen crown rot or a similar type of disease cause complete dieback and death of a few plants.

    We pinch or prune before that a branch is formed. It is the pinching that causes the branches to form. I usually prune about an inch above where that the leaf is attached to the stem on hardy hibiscus. New shoots should form on the stem at the base of the last two to four leaves below your pruning cut where that the leaves are attached to the stem.

    Your lack of pinching had nothing to do with your hibiscus not returning the following year.

    ReplyDelete
  3. I live in MD and last year by LB grew but never bloomed. I think bugs got to it before I could help it. I cut it all back but it is now mid May and nothing seems to be growing. Do you think the whole thing is dead or is it too early to be growing back. It has been unseasonably cold here.

    ReplyDelete
  4. Sorry to hear that you are having problems with your hibiscus. There are many types of hibiscus. Some are tropical and will not come back after a Maryland winter. The stems of the hardy hibiscus usually die completely back to the ground. The new stems of hardy hibiscus emerge from the ground rather than from the above ground part of the stems. In warmer locations on campus the new shoots are about 12 inches tall and in partial shade where it is cooler, they are about 2 inches tall. If you are at a higher elevation where it is cooler, there is a chance that you hibiscus is still alive. You might want to consider contacting the Master Gardeners in your area for additional information.

    ReplyDelete
  5. I have had my Lord Baltimore for more than 10 years. Several years ago
    the middle of the plant did not come up but split in two, one in section
    in front and one in back of the middle of the original plant. Is there any way to encourage the plant to fill in the middle again?

    ReplyDelete
  6. Fortunately, I have never experienced or witnessed what you described happening to your hardy hibiscus. Unfortunately, that means that I have no experience with the problem that you described. If your hardy hibiscus has not filled in the middle in several years time, I am doubtful that it ever will fill in the middle as 'Lord Baltimore' has been a very fast and vigorous grower for us. How far apart are the two sections? My thought is that if the two sections are less than two feet apart, it will not be an issue by around June 15th as your hibiscus should be so large by that time that it will look like just one plant. If the appearance before that time is not appealing to you or you feel that the two sections are too far apart, consider transplanting one section to your desired location. Transplant the other section to another location in your yard or consider sharing it with someone. We have had good luck transplanting even very large hardy hibiscus when done in the first part of April, just before that any new shoots appear or if the shoots are less than 1/2 inch in length.

    ReplyDelete
  7. They are only about 8" apart. The section is front is not doing as well
    this year as in the past. The back section is already a couple of feet tall. Suppose the front section will bite the dust one of these years. Too
    big to transplant this year but may consider next. Thanks!

    ReplyDelete

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