Saturday, November 27, 2010

"I'd give it three years"....... how perennial are perennials? and other awkward questions.

Ever bought a 'perennial' from a garden centre and then wondered why it drops dead after a number of years? You like the thing so you try it again. Ditto. Naturally you blame yourself/the soil/the fact that the dog peed on it, but then you discover that everyone else has the same problem.

Welcome to the world of the 'not-perennial'.

Annual, biennial, perennial - three words which actually represent points on a gradient - from ephemeral to Bob Brown's "bomb-proof". Between 'biennial' and 'perennial' there are a host of short-lived perennials which do generally die after a few years. Their saving grace is that often they self-seed. If they don't its a bit of a con the hort industry telling us they are perennial.

How often do the garden reference books tell you that a perennial is short-lived? Or if it runs about, and if it does, how rapidly or its mechanism of spread. Lots of questions the books don't tell you the answers to.

But go to something like a Hardy Plant Society meeting and the air is thick with anecdotal material on just these kind of questions. So, I thought, why not design a research questionnaire which aims to get experienced gardeners answering carefully targeted questions on just these issues? As it happens there was an EU project: European Regional Development Fund (ERDF), European Territorial Cooperation 2007-2013.Interreg IVB North Sea Region Programme, which I was able to join and get (pretty decent) funding. Hurray for the EU! And of course to the Landscape Department of the University of Sheffield, in particular Nigel Dunnett and Mel Burton.

So, here are the results.

There is the 'lite' version, reprinted from the Hardy Plant Society journal (long-term plant performance), and for those of you who feel up to it, the full report.


Keith said...

As you say in the final paragraph, we all have differing experiences with our plants. For example, not only is my Monarda longlived (6 years now), but also invasive. Every year I tear chunks out to keep it in check, giving away the waste. Some friends have great results, others very little.

The Intercontinental Gardener said...

Of course, the life span of plants is very much affected by the soil, climate etc, but your survey gives valuable information about what to expect "generally" from a plant, even if it might behave differently in my particular garden. The more knowledge, the more patience... both with the plants that are slow to establish, and with myself when I keep loosing the short-lived ones. Thanks for sharing the project.

Janet/Plantaliscious said...

What a fantastic resource - thank you for sharing it.

allanbecker-gardenguru said...

Thank you for the update on short lived perennials. I was devastated to see the Heuchera hybrids on that list.

Chris said...

Thank you Noel. I had read ab out your research so was interested to read the results. I think I can concur with most of the findings which is very reassuring. It is a very valid point you make about the Nursery industry and its labelling. We also need to know which plants will perform reliably in our naturalistic schemes. I have learnt this by a good deal of trial and error but I'm sure the novice gardener needs better guidance. Good luck with further research.

balsamfir said...

Just reading backwards through your wonderful blog. We do have differing experiences, perhaps also because of different climates. I live in zone 4a of northern New York, and here Echinacea seeds reliably, and is also one of our more reliable perennials(for many people). Heuchera has made it 15 years for me if I divide it regularly. I would love it if Hellebore would seed. Mine is losing to Epimedium rubrum (also a nice seeder). Very glad to know I'm not the only one who can't get Achillea's to survive. Finally, I tried to look at the long version, but it wouldn't download. Would you possibly consider emailing it to to me?

martine Warlop said...

Do you know if a similar study has been made in France . If not, may I try to translate it as a subject for a meeting of gardeners?
Thank you.
Martine Warlop