Forsythia Pruning

EdW

Hiya,

Need help with an old, crowded, but thin forsythia!

Please take a close look at the two photos - should I prune it hard right now before it flowers, or after? I’ve read conflicting approaches which depend on how overgrown it is. Ours isn’t overgrown in that ‘rampant’ way, it’s just been pruned incorrectly for years and allowed to get stuffy and matted. The stump on the right I thought was all dead but it wasn’t quite that far down in reality; so that accidental cut was the only live wood I’ve pruned this year.

If I prune further now, should I take out the central thick, tallest stem? Or even more drastic action? Or is it actually better to do any of this later, after flowering, as standard?

Thanks!!

Obelixx

These flower on old wood so if you prune now you'll lose the flowers.

Best to wait till it's finished flowering and then, without delay, cut it back as hard as you like and give it a good feed of slow release fertiliser such as BF&B plus a good drink of liquid seaweed or tomato fertiliser for an instant tonic.  It will grow new stems that will flower next year.

shane.farrell

Bear in mind that some older ones flower on two year old wood. Mine does. If that were mine I'd let it flower then cut to the ground. You can then control the regrowth.
That said I am taking mine out this year and replacing with a dwarf Pampas and a Cotinus as my wife wanted something with red leaves and I don't think Forsythia earn their keep.

EdW

Thank you both! I’m terrified of killing the poor thing. We’ve had two others in the garden both of which have died and this one’s been here for yonks.

I’ll prune it hard after flowering as you’ve advised, but I think I’d prefer to do a renovation prune over a couple/few years!

shane.farrell

That's an option too 👍. I understand layering or sticking the stems of one year old growth in the ground work well as a backup or if you want more.

Obelixx

In that case, just take out 1/3rd of the stems to the base after flowering and then give it a feed.    Do the same every year, taking out the older stems (you can tell by the bark) and you will automatically renew your shrub every 3 years.

shane.farrell

Over subsequent winters you will definitely see a gradual improvement in shape and the shrub will just look healthier. I tend to go to an open look with this sort of shrub.

Hostafan1

I pruned my forsythia a couple of years back. It must have been almost 3m tall and even wider as, at some point in the past, a branch had split and fallen sideways then carried on growing.
My method was to take a bow saw and cut it to about 2inches above the soil level . It worked a treat.