I planted a row of Thuja plicata somewhat over a year ago as a boundary hedge. It's quite shady so they have not grown much but they are surviving and growing.

They're about 3' (1m) tall but quite spindly, should I already be pruning them, if not when? There's not a lot to prune but I don't want to miss the opportunity especially as I want to keep growth as low down the trunks as possible. What is the right pruning regime for these, given I want to keep them about 8 feet high (2-3m) eventually as a dense hedge?

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1 Answer 1


You don't "prune" red cedar, you just trim the ends of the branches to keep them to the size and shape you want.

So you don't need to do anything until they get nearer the height and width of the hedge you want. You can expect them to grow about half a meter per year.

You would normally trim the hedge twice a year, in spring and in late summer (i.e. August).

Heavy pruning is likely to produce holes in the hedge or dead patches with brown foliage. Don't prune from September until they start to grow again in spring, otherwise you increase the risk of the pruned wood dying back.

  • Ok that's interesting, so you basically trim to the box you want the hedge contained in, let them get big enough then start thickening up rather than keeping them trimmed to promote dense growth from the start?
    – Mr. Boy
    Commented Sep 13, 2020 at 12:53

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