Wednesday, January 20, 2010

Growing perennials in grass

A question at a public lecture at the University of Gloucestershire (bet you didn’t know that Glos. had a Uni. …. well you do now!) last night made me think I should write this up from my PhD. A long time ago (late 1990s) I decided I would run a small-scale experiment on growing perennials in rough grass. I wanted to see if it was possible to create a ‘perennial meadow’, where the grass was cut only once a year. Around the same time James Hitchmough (now at the Uni. of Sheffield) had a similar idea. He, needless to say, was larger-scale and more scientific. Our hope was that we could come up with an alternative to just boring mown grass or long shaggy, but rather untidy grass.

Not actually a great success, but not without some hope.

Problem is, nearly all ornamental perennials have a dormant season, during which our native grasses (which makes up both lawns and pasture) and pasture forbs (like dear old creeping buttercup) are growing, give ‘em a mild winter and the things will grow for 365 days a year. So, perennials are immediately out-competed. This is why you get (or one reason why) you get such fab wildflower meadows in places with freezing winters where nothing can grow Oct/Nov to April, like the Alps, eastern Europe etc. – everything here starts off on a level playing field. Our British/NW European long growing season is just too grass/creeping buttercup+other winter-green forb – friendly.

So, we sprayed off (with Roudup) or dug out circles of grass and planted and watched results. Almost inevitably, both James and I found that plants in year 2 and onwards were so much smaller than we were used to seeing them in borders, out-competed and weakened by the grasses. Very few were able to survive and prosper. My conclusions in my thesis say:

• Effective basal cover, combined strongly with:
• Early emergence
• At least some ability to effective spread by ramets, (ie. new shoots)
• Root competition may also play a part – further research is indicated.

Which means geraniums, especially G. endressii, G. versicolor, G. x oxonianum types,(see pic at top) big inulas (e.g. I. racemosa - see pic below), Rudbeckia laciniata and that's about it. Asters did ok for a few years then got slugged. Euphorbia cyparissias did ok with its manic runner production. Meanwhile James found that Lychnis chalcedonica and Papaver orientale did respectably well too.

Those on planet Academia can check out these:
Hitchmough, J.D. (2000) Establishment of cultivated herbaceous perennials in purpose sown native wildflower meadows in south west Scotland. Landscape and Urban Planning. 714, 1-15

Woudstra, J. and Hitchmough, J.D. (2000) The enamelled mead: History and practice of exotic perennials grown in grassy swards. Landscape Research. 25,1, 29-47

Hitchmough, J. and Woudstra, J. (1999) The ecology of exotic herbaceous perennials grown in managed native grassy vegetation in urban landscapes. Landscape and Urban Planning. 45, 107-121

Sunday, January 10, 2010


Its hardly crept above freezing anywhere in the British Isles for some ten days now. Last winter was an old-fashioned event, with a frost every morning here for two months, but this one is so like the winters of my childhood, in the Kent/Sussex border area, where every winter in the 1960s and early 1970s there was at least one massive snowfall.

So, where does this leave us with plantlife? ‘Zonal Denial’ to borrow a phrase from American (Oregonian) gardeners has been all the rage over the last twenty years, planting stuff out from warmer climes in the hope that it will survive. And much of it did: vast mimosa trees turning brilliant fragrant yellow in London squares, agaves in urns, olive trees in gardens. Gardeners have always liked to push the possible, and with so much new plant material coming into the country, at a time when we have had a run of mild winters, there have been temptations aplenty. I was (note WAS) part of the trend – indeed perhaps helped start it off. All that exotica that we began to play with in the 1980s and 1990s. In my case, selling plants on a regular nursery stand at RHS shows in London (in the days when these events used to happen) made me realise just how good the city was for growing plants – the urban heat island effect, and a fairly dry climate. People started buying supposedly tender plants like Abutilons and Banksias and then coming back next spring to tell me that it had survived the winter with no protection/ flowered all winter, etc etc.

The architectural plant craze helped as well. Importers of palms, yuccas, bananas and tree ferns had a field day: mild winters, a rush of new plant prospecting AND lots of young folk who had no memory of cold winters with lots of money to spend. Big of a boy thing this – the rather macho world of big exotic-looking stuff, when you could boast of what you could get away with next spring – a bit of defying the ruling gods.

I got out of all this a long time ago, round about the mid 1990s. For me the future lay in stuff which you did not have to worry about every winter or celebrate its survival every spring. The stuff that began to excite me was the perennials and grasses I saw in Germany and Holland, for which a British winter was nothing. Part of me just lost interest in the stress of growing borderline hardy plants. After all, I was now gardening in Hereford, not the south Devon coast.

This winter will probably leave a lot of vegetable mush. Its important we learn from it, about the plants that survive and why they did. It won’t mean we’ll have to go back to the garden world of the 1970s, because there really is a lot of new plant material we now have, a lot of which will probably be ok. But at least the sillier excesses will hopefully be curbed. Like the fool who planted an olive orchard in Devon, and hopefully (and this makes me cross) the wholesale nurseries who sell things like Lavandula stoechas with no warning on the label about its borderline hardiness. A periodic reality check is definitely a good idea.

I can’t help point out though that Mexican Salvia coahuilensis was still flowering before getting covered in snow!