When and how to prune a hedge??

This may come as a shock to you but I've never pruned a hedge.

When do you do it...summer, winter etc? And how often?

If I want a nice dense say, 2-3m hedge as the end result for the Viburnums, should I start clipping these now (photos attached)? FYI, I haven't touched these since they were put in the ground in late 2016.

The lily pillys were a bit larger when planted and I would like these to be a dense 6-8 m screening hedge. Do I prune these or just leave them to continue growing?

 

Regular pruning will encourage bushy growth, which is what you want.
Ask at a local nursery when is the best time for your area.
Many say in winter while growth is slower, ready for the new growth in spring.
Marg

 

What are they?

Time to trim varies - i trimmed my robinias, azaleas & magnolias (a little late as it has set flowers for next year) yesterday.

I usually trim most things after flowering (except for fruit trees of course).

 

Use a battery powered hedge trimmer. I worry I will damage the cords on plug in ones.

The tops need cutting off to encourage more growth, you want new growth into "thickness" not growth into height, Gentle steps.

 

So based upon the photos, should I do it now (in December)? How short do I prune them down to? The Viburnums are about a 0.5-1.3m high.

 

Possibly a little late in the year, spring before growth is better.
All of the bigger ones need the tops cut off.
Me 3rd picture at fence height
Others just need that center bit off that is growing up, maybe 1/3 to 1/4 of height
Keep the water to them
I would do it now but not if any really hot days in next week or so,
I am very much an amateur gardener. I just trim my small hedge when needed

 

Agree with @Shogun - you should be able to get away with about 1/3, possibly a Boy prune on the larger ones. Viberniums are virtually indestructible and will grow to 3-4m (mine are in a raised bed, growing in medium to heavy shade but still at the 4m mark). Currently in flower but will need a trim regardless.

 

Boy Prune:

 

That's only a small area,a hand held pruner would do the job..plus if you add some sugar cane mulch --- dynamic lifter into the root area that will help it grow and level it out..imho..

 

Thanks! That's helpful. Should I ideally wait till the cooler months, say June/July or do it now (in Summer)?

 

I’d do it now.

You don’t need a hedge trimmer, just sharp secateurs. Cut back all the long single branches by two-thirds. This will encourage them to branch out.

And you don’t have to do it all at once, a bit at a time is fine.

We live in Brisbane and it cut back shrubs whenever they start to look straggly, unless they flower once a year and then it is after flowering.
Marg

 

Do it now as they are quite young and ready to to be knocked into shape.

Lily pillies need alot of tlc, being so fast growing they can soon look tired and be short lived (10-12 yrs ). They dont like phosphorus which is in common fertilizers . Blood and bone or organic type best. Mulch.

Check that psyllids dont infest , even if the nursury says that variety is resistant.

 

Yeah I need em to be at min 4m to screen the neighbours (I have it planted alongside the house, as well as the front).

Need the lilly pillys at the rear to get to say, 6m. Don't know if they will though. Kind of regret I didn't grow (Little Gem) magnolias there though. I prefer the look and the large glossy leaves but everyone was telling they'll take a minimum of 10-15 years to get to 6m.

I'll also try some of the tips re: mulch and fertiliser. The growth since 2016 has been a little underwhelming, or maybe I'm expecting too much.

 

Yes, they said they were resistant lol.

 

Should I trim them on the sides too...so they don't fan out too much (horizontally)? Ideal scenario is narrow, upright growth.

 

You might squeeze some trellis in behind and try to espalier the branches

 

Sure. Trim any branch going in a direction you don’t want.
Look at the place where you plan to cut. Sometimes there are little shoots where the leaf joins the stem. Cut A little bit above shoots pointing in the direction you want to encourage growth.
Marg

 

OK.

Damn this looks like work. The property is currently an IP with the possibility of us moving in when the tenants leave...so I can't be around to show the love. The lilly pillys at the rear are tied to a stake to promote upright growth. Hopefully that's enough bc a trellis is beyond my level of tolerance work wise.

 

Alright will do. This is becoming harder than rocket science.

 

I am lazy. I just get my battery hedge trimmer out and trim to shape I want. I do roses by hand. Trimming will make the plants more dense. In fact I got hedge trimmer on a pole for Christmas to keep an olive tree in check.