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How to trim forsythia?

Discussion in 'Landscape Architecture and Design' started by agrostis palustris, Aug 7, 2002.

  1. agrostis palustris

    agrostis palustris Banned
    Posts: 117

    How do you trim forsythia? I just did a pruning job for a customer which included the severe pruning of a couple rhodi's as well as trimming back some forsythia. The customer requested that I get the top of the forsythia... however that is pretty hard to do. There are 3 of them which are in question. They are each about 8 feet tall. 2 of them combined are 30 feet across and probably 50 feet in length. The other 1 isnt as bad. I have access to a stihl extended shaft pole trimmer, but that won't do me much good. I could also get a trimmer attachment for my HT-75, but that would be heavy as all heck. Not ready to spring the $120,000 for the new Hi-Ranger yet... so that is also out of the question.
  2. ipm

    ipm LawnSite Senior Member
    Posts: 264

    At this point in the season I would sheer the Forsythia(use a ladder, or bring the tops down some) Extended sheers at 8' should not be problem. Late Winter I would cut them back. How far back did you prune your Rhododendrons???? i have never had much luck pruning this plant drastically.
  3. LawnLad

    LawnLad LawnSite Senior Member
    Posts: 738

    Any pruning now of the forsythia will reduce the flowers next spring. The best time to prune forsythia is after it blooms, much like lilacs.

    If you must prune now, head the branches back selectively. If budget doesn't allow for hand work you can sheer them, however, this will certaily destroy the natural branching characteristic and will most likely remove more flower buds than if you selectively hand prune that which you must prune now.

    The natural branching characteristic of the plant is whispy and flowing. Many people don't like the unkept look of the forsythia - it's a plant better suited to out of the way locations where they have room to grow and do their thing. Not a great plant in a high maintenance bed.

    I have seen this plant in places where it has been continously shorn (sheered) and it blooms full of yellow each year. Go figure... I guess it depends on the look you want.

    Specifically answering your question of how to prune the monster... I would at this time remove the three D's - Dead, diseased and damaged wood. I suspect with a plant the size you describe you'll have some deadwood in it. Sounds like you may be crawling on your belly to get to the base of the plant where you'll want to make your pruning cuts for removal. After you remove the 3 D's, do some light thinning of those branches that are crossing or rubbing others. Lastly, very light heading back of some of the "out of control" branches. You can use pole pruners, loper or hand pruners. Try to make each cut back to a lateral branch or bud. May be tough to do with the pole pruners.

    Next spring after the bloom is finished before the plant leafs out do more thinning and heading back. Remove no more than 1/4 of the plant. You can rejuvinate the forsythia over three to four years by removing 1/4 of the oldest, woodiest canes/branches each year. The reduced shoot to root ratio will encourage new, young, vigerous growth. You can than work to keep the plant headed back to a more appropriate size if need be. But it will take time since you can do all the rejuvinating at once.
  4. Runner

    Runner LawnSite Fanatic
    Posts: 13,496

    Yeah, what HE said. This really couldn't have been explained better. Very well put, and informative. (Well, all except for the last sentence, but we know you meant to say CAN'T instead of can. {been there - don't you just hate it when that happens}. Anyway, geat thread, and even BETTER post. Good work, LawnLad!:)
  5. KenH

    KenH LawnSite Bronze Member
    from CT
    Posts: 1,622

    I think he was asking how to reach the tops, as opposed to how to trim forsythia in particular. If the shrubs are together, and pretty dense, I lay an extension ladder on top of the bushes. Then I climb on the ladder, crawling along, cutting. The forsythia have to be pretty think to hold the ladder, but we have done this many times with success.
  6. agrostis palustris

    agrostis palustris Banned
    Posts: 117

    Thanx Ken. Your answer was more along the lines I was looking for. What is the biggest ladder you have ever placed on top of thick forsythia? I was able to lean my weight into it the other day and it supported me no problem.
  7. AGLA

    AGLA LawnSite Bronze Member
    Posts: 1,742

    You can always try to drag a step ladder underneath, thin a spot, and pop up through it.
    I would not worry that much about blooms as they bloom all over the younger branches. They will be covered in blooms next spring - except there will be less shrub to cover.
  8. Planter

    Planter LawnSite Member
    from Utah
    Posts: 214

    It should be trimmed in the spring, shortly after blossom. I thin one-third out (taking the oldest wood) and then shape it. The blooms next spring will occur on the wood and buds developed on this years growth. The rule of thumb from my woody plants instructor was, "If it blooms before Memorial Day prune in the spring, if it blooms after Memorial Day prune in the fall."

    Hope this helps.
  9. KenH

    KenH LawnSite Bronze Member
    from CT
    Posts: 1,622

    I usually take my 30' extension ladder and open it to the size of the bush. the longer you can open it, the more your weight will be distributed.
  10. LawnLad

    LawnLad LawnSite Senior Member
    Posts: 738

    ooops... I think you're right - you did ask on how to get on top of the forsythia. I guess I didn't read it close enough on first reading. Well, hopefully the info helped someone else.

    I too would lean a ladder into the bushes... don't have to do it very often, but it works.

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