Q. I noticed on your Twitter feed that you’d identified Ribes Sanguineum flowering early in Alexandra Park. Can I buy this shrub or could I take a cutting?
A. You should be able to track down and buy one of these excellent flowering currants, but if you’ve a little time and patience it’s certainly worth giving cuttings a try.
Ribes should in fact be a relatively easy challenge to grow from cuttings, and March just before bud-break (in a normal year!) is a good time to try.
Use the most recent growth, cutting a length of about 15cm. Cut above the bud at the top, and below a bud at the base and in brief, insert the cutting in a trench in the ground or in a pot mixing a lot of sharp sand with the soil or compost. Bury at least half of the stem. It will probably take a whole growing season for roots to develop.
The excellent RHS website gives a more detailed account.
You can try cuttings of almost anything but it’s worth bearing in mind that you’ll be perhaps 3 years behind a garden centre size shrub. And please note that here we are referring typically to deciduous shrubs, or “hardwood cuttings”.
Oh…. And you will of course ask permission before taking a cutting from someone else’s plant!!
Q. Do you think cutting a Penstemon down is beneficial to the plant, and if so when should I do this and by how much?
A. Very much so. If you don’t prune they have a much greater tendency to be leggy, floppy and scruffy
It’s probably best to wait until chances of a frost are fairly remote but in London April is a perfectly reasonable time to prune back a penstemon. I’ve found that cutting them down by about a half will build a strong stocky plant which will flower well.. Most penstemons don’t seem to start flowering until mid summer, on new shoots.
This seems to be a fairly underrated genus of herbaceous perennials. They come in a wide range of colours with striking flowers which can last many weeks into late summer and autumn. Dead heading will help prolong the flowering period. They don’t die down completely in the winter, and therefore do not leave you with a gap in the border for four months, and they fit in well in both traditional and contemporary settings.
Some particularly striking penstemons are “Garnet” bright red and hardy, “Sour Grapes” pinky purple and fairly hardy and “Heavenly Blue” heavenly blue and fairly hardy.
The common name for penstemon is Beardtongue, deriving from the hair on the end of the prominent stamen which protrudes from the throat of the flower. This sounds like a rather nasty condition, but in the herbaceous border it is certainly something to be encouraged.