Pruning - what, where and when?

Greetings from the sunny south-east.

I'm still confused about this. Nearly all my plants are in pots and I would really appreciate some advice about pruning as above.

I suppose they all require different treatment, but any general guidelines as to time of year, how low, and so on, would be very welcome.

For example, Buzz Buddleia, Verbena Bonariensis, Solanum (as below), Erysimum and so on.

By the way, silly question, I know, but I had some petunias in pots which are well done by now, but the green shoots above the compost still look healthy. If I cut these down, and they survive the winter, would they do anything next year?

Thank you, thank you, thank you...

Neil

 

Buddleia - prune hard (doen to 18")any time between now and March.I generally do mine about February.

Ditto Verbena Bonariensis, essentially it is a hardy perennial but the tops may stay more more less evergreen in a mild winter. If they are tatty come spring, cut them off down at ground level. If they still look OK you can leave them on or remove them to showcase fresh growth. It will still be alive under the ground whatever you do.

Erysimum - don't prune now as it flowers in spring and will need all its growth tips then to produce flowers.

General rules: prune straight after flowering is finished, so the plant has nearly a full year to form new growths with flowering potential. If you were a month or two late it probably wouldn't matter too much as the plant would still be able to produce some blossom.

So, if it is a spring flowering plant i.e. March to June, don't prune in the Autumn.

If you have foliage plants such as euonymus there is more leeway as to pruning time. I generally do mine when they seem to need it which is between March and July, I guess.

Never grown Solanum, so not sure.

Many plants will have more nuances regarding their treatment so if you have anything you're specially concerned about mention it here and I'm sure someone will know what to do about it.

For example, pyracantha is valued for its berries in Autumn. In order to have berries it must be allowed to flower. If you prune it in early spring you cut off potential flowering stems. If you cut after flowering then the developing berries are removed. If you cut it in Autumn then the display of berries is removed. So I've never worked out what the best time to prune it is. In practice, the wretched things need pruning constantly, anyway.

 

For the buddleja (which is the only one in your list that I have personal experience of), I'd say it depends on a couple of things.

Once buddleja is established (by year 2 usually), my regime is this:
* Always cut of dead flower spikes. Buddleja forms flowers on a sort of trident arrangement, with the centre spike in the trident producing a big flower cluster, and the two side ones having tiny flowers on stand-by. Those tiny ones wont develop if the central one is allowed to go over, so cut it off as soon as its past its best. Then you get more blooms for longer.

* If it looks scruffy, tidy as you see fit as and when you like. Buddleja is tough.

* Once you're pretty sure its done flowering for the year, I take it down to about half its height (late Autumn).

* In spring, I cut it down again, to just a few inches from the ground. It sounds brutal but it will very quickly grow back once the year gets underway.

Personally, I don't do that regime in year one. My theory being that its best to let it settle in and build up good roots. The exception is if by its first winter it is unusually well developed, then I'll cut loads off just to prevent the wind from whipping it out before its roots are well anchored.

 

Many thanks.

 

Oh, just noticed your last question. Sadly, the petunias have given their all, and will not survive the winter. However, if we have a mild spell, you might get a few last flowers from them before the first frost "does 'em in".

 

However, petunias are actually perennial, I think. So if you can keep them completely out of the frost the plant could continue to grow next year. But you will probably get a better display starting again with fresh, young plants and most people think that's worth paying again for rather than bother trying to overwinter them.

 

Thanks, both.