Cutting back

Re: Purple top (Verbena bonariensis) - my instructions state that they
should be 'cut down' once flowering has finished.

Last summer i didn't prune/cut back/dead head at all.

So this spring they looked a bit of a sorry state!

This week at last I 'dead headed' them, removed some dead leaves and cut
back the tall stems but only to remove broken parts of stems or obviously
'dead' parts - I didnt cut down right to the base.

They still look a bit of a mess but there is now new growth appearing both
in form of completely new stems AND new branches from the existing stems
left over from last year.

The question is in an ideal world, going back to last summer when
flowering had finished, should i have cut ALL stems down right to the base
- hence starting anew this spring. Would that achieve better results in
the long term or would that have been over doing it?

Re: Cutting back

Reply from Kathy C

Hi, Kevin,
In most cases, it is good for the plant to deadhead or cut back spent flower stems after flowering - it makes the plant use energy for stronger roots and stronger vegetation. As far as how low to go and when, you will get conflicting advice. What you do also depends on how cold the winters are where you live. I live in an area with a mild winter. When I am sure it has finished flowering, I cut back the spent flower stems to the clump of basal foliage. Then, in late autumn, I cut back low to the ground. This produces a nice, bushy basal clump in spring. If you live in colder area, I would still cut back spent flower stems after flowering. Then, by mid- to late autumn when it is getting colder, add a dry mulch. Leave the cut stalks to protect the plant from frost damage. Then, in early spring, cut back the tatty old foliage to make way for fresh new growth.
All the best,
Kathy C

Re: Cutting back

Reply from ELAINE HUTSON

If they are still green they have made it through winter and cutting them to the ground is okay. They do seed freely so no harm done, even if you lose the mother plant.

Re: Cutting back

Reply from Nicola

Hi Kevin. Suzette replied in our Facebook page too:)