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June 2009

Britain's Favourite Perennials

When the British version of my Encyclopedia of Perennials came out two and a half years ago, I did some lectures entitled Britain’s Favourite Perennials featuring the Top Ten perennials in Britain.

But how did I decide which were the Top Ten, and in what order? Well, I asked the Head of Buying at the foremost plant centre in the country, at the Royal Horticultural Society’s garden at Wisley in Surrey, to tell me what his best sellers were in the previous year – that seemed a pretty good guide.

Well, I’ll again be lecturing on the same subject later this year so I asked him to give me his most recent figures and today I’ll let you into the secret. First with the best selling genera, and next time with the best selling individual varieties. So here goes. American readers will notice which two plants are not in the Top Ten:
Dianthus Tickled Pink ('Devon PP11'). Image: ©Sue Drew/RHS Trials Office 10 New at Number Ten – Dianthus. Not even in the Top Twenty three years ago, and with no individual varieties in the top twenty five, I suspect that the recent flood of prolific dwarf types from Whetman Pinks accounts for this increase in popularity.
9 Same position as last year – Echinacea. The appeal of all the new colours and flower forms is balanced by the fact that many are proving more difficult to get through the winter than we’d like.
8 Down one place – Penstemon. Slipping from seventh to eighth place, but with a pretty small drop in actual sales, penstemon remain popular for their long season of dependable colour.
7 In from nowhere – Salvia. Mysteriously absent from even the Top Twenty last time, this is a case where enthusiastic articles in The Garden, the members’ magazine for the RHS, may have encouraged demand.
6 Down from Number Three this year – Euphorbia. I suspect that this drop may be the result of heavy promotion of new variegated varieties not being matched by their quality and longevity in the garden.
5 Same as last year – Iris. The vast variety of types allows changes in trends to be picked up by oneAgapanthus 'Midnight Star'. Image: © kind of iris as another becomes less fashionable.
4 Roaring up the charts – Agapanthus. Our changing climate (allowing gardeners in more parts of the country to grow more varieties), the increasing popularity of growing perennials in containers and some very active specialist nurseries all helped boost enthusiasm for agapanthus.
3 Down one place – Helleborus. A small drop in sales numbers, but it’s more the huge rise in sales of the new Number Two plant the pushes them lower.
2 Almost 40% up in sales – Heuchera. Placed fourth three years ago, the continuing stream of good new varieties, with two in the top ten of individual best sellers, solidifies enthusiasm for these superb foliage and flowering plants.

Geranium pratense 'Laura'. Image: ©Plants for Europe 1 And still at Number One of the best selling perennials, but only just – Geranium. The lead has shrunk so much that Geranium is now only 0.22% ahead of Heuchera while three years ago it as 13% ahead of Helleborus. But their versatility, easygoing nature, and the introduction of good new varieties keep them at the top.

And that's right, North American readers - no Hosta and no Hemerocallis.

Next time I’ll look at the best selling individual perennial varieties… There’s some surprises there to.

Thank you to Malcolm Berry, Head of Buying at the RHS Plant Centres at Wisley in Surrey, Rosemoor in Devon, Harlow Carr in Yorkshire and Hyde Hall in Essex, for getting these fascinating figures together for me.

Buddlejas not growing in patio pots

Buddleja 'Buzz Magenta', new from Thompson and Morgan. Image: ©Thompson & Morgan I’ve mentioned before here how some nurseries stage their plant pictures using cut material to try to make their new introductions look more impressive than they really are. Remember these ligularias?

Well here’s another example.

Over on my Royal Horticultural Society New Plants blog I’ve just written up two new patio buddlejas created by Thompson & Morgan’s Charles Valin at their plant breeding operation in Britain. 'Buzz Magenta' and 'Buzz Lavender' have just been released to British gardeners and they sound very impressive.

Buddleja 'Buzz Lavender', new from Thompson and Morgan. Image: ©Thompson & Morgan But the pictures! These two new buddlejas are so dwarf that they’re ideal for growing in pots on the patio. So someone just went out and cut some branches from the plants, arranged them nicely in a pot and took their picture! And that’s exactly what it looks like. Click on the pictures to enlarge them and see what I mean.

If they grow so well in pots, can’t we have pictures showing them doing exactly that – growing in pots?

British gardeners can order the Buzz buddlejas from Thompson and Morgan. They're not yet avaiable in North America.

Deer resistant – guaranteed!

Kalmiaangustifolia14000-600. Kalmia angustifolia (sheep laurel). Image: © There’s a little native shrub growing in our damp woods that never, EVER, gets eaten by the deer. Just in case you’ve missed me bashing on about it in the past, the white-tailed deer are a menace here in north east Pennsylvania, eating wildflowers and native tree seedlings with equal enthusiasm. But Kalmia angustifolia, sheep laurel, is never eaten.

This little relative of the well-known mountain laurel, Kalmia latifolia, the state flower of Pennsylvania, only grows about 38cm/15in in these parts but can apparently reach 90cm/3ft or even 1.8m/6ft. Its pretty clusters of flowers are grouped all round the stem but are only about 12mm/0.5in across. It runs gently at the root to make wide, open stands of rather sparse evergreen ground cover under our oaks and maples.

It’s a shame it’s not a little more colourful. But not only are the flowers small, but they open under tufts of new foliage so that as you look down on the low-growing plants the flower clusters tend to be hidden.Kalmiaangustifolia14022-600. Kalmia angustifolia (sheep laurel). Image: © There are half a dozen named forms, in various colors, listed on the University of Connecticut website (scroll down) but they’d have to be a lot better than the wild form to tempt me.

Often cited as poisonous to sheep and cattle – hence one of its other common names, lambkill – it is not, apparently, actually poisonous to deer but they seem to leave it along anyway. They eat the mountain laurel, K. latifolia, which is regularly browsed to about 1.5m/5ft, and almost everything else.

What we need, perhaps, are hybrids between deer-resistant K. angustifolia and deer-favourite K. latifolia to give us flamboyant shrubs the deer won’t eat. If only it were that simple. Such hybrids  have, in fact, been created when pollen from K. latifolia was used to pollinate K. angustifolia and 2000 seedlings germinated from almost 10,000 seeds. Almost all the seedlings were weak and died. If the white form of K. angustifolia was used then more seedlings survived but their main ornamental feature was the bright yellow young growth.

Well… perhaps I should try to get hold some of those taller forms… or perhaps in the garden with better soil and few doses of liquid fertilizer iwild plants will make more impressivespecimens. But, out in the woods, at least it’s a pretty plant to break up the dominance of the two ferns the deer don’t eat – the hay-scented fern, Dennstaedtia punctilobula, and New York fern, Thelypteris noveboracensis.

Fore more on Kalmia angustifolia, sheep laurel, and creating hybrids see Kalmia: Mountain Laurel and Related Species by Richard A. Jaynes.

Shameless orchidaceous nepotism!

9781604690552l My wife’s new book has just been announced. It’s called Bloom-Again Orchids: Tips and Tricks for Glorious Displays Year After Year by judywhite. The title says it all, really. And it's great!

People think orchids are difficult to grow and of course some are. But this book is about orchids which anyone can grow and which are readily available across America and across Britain in nurseries, garden centers and even chain stores and markets. They’re easy to find, and easy to grow. And of course they look fabulous.

So if they’re so easy why do we need a book about them? Well, it’s just like plants in the garden – hostas like shade and echinaceas like sun and they won’t thrive unless we give them what they need. Same with orchids, give them the light and the temperatures they need – no problem.

In a lively accessible style, this book explains their features, explains what they like, and gives a glimpse into their background. I looked it over as a work-in-progress, I can assure you it’s a great read. What's more, judy’s stunning pictures will make you want to grow every single one. And of course you can – with a little help from this book.

You’re probably familiar judy’s earlier orchid book, the multi-award winning Taylor’s Guide to Orchids. Be sure to take a look her new book.

Bloom-Again Orchids will be published in the fall. You can pre-order Bloom-Again Orchids in North America here, and in Britain here.

And check out judy's recent blog post about South African Disa orchids over on the new Timber Press blog.

That OK dear? You don’t think I’ve overdone it?

(Actually, it’s a really good book!)

Ornamental rhubarbs - send your pictures to the RHS

Rheum trial RHS. Image: GardenPhotos.comThe ornamental rhubarbs, Rheum, are dramatic flowering and foliage plants making bold specimens with, at their best, a very long season of interest. They're related to the culinary rhubarb, of course, but look better! You can help the Herbaceous Plant Committee of Royal Horticultural Society with our research on these plants.

After the trial of ornamental rhubarbs held at the RHS garden at Wisley, just outside London, ended in 2006 the plants were moved for further assessment and we took a look at them a few days ago. Frankly, they're a bit of a muddle. It's not as if there's a huge number of them, but the problem is that they've become so mixed up that when you buy a plant under a familiar or promising name you've little idea of what you're actually going to get. It was clear that many of the plants we assessed were wrongly named and some good plants were not represented.

These plants have five good features: the unfolding spring foliage can be very colourful, often dark red; the mature leaves can be impressive too, especially if they retain their red colouring on the upper surface and have an attractive shape; the flowering heads can be bold and colourful; the seed heads can also be impressive; and the whole plant can make a fine and imposing specimen.

So we'd like you to send us pictures of really good ornamental rhubarbs. If you have plants which are especially impressive in one, some or all of these ways - please send me a picture. Tell me the plant's name, where you got it and when you got it and it will help the Herbaceous Plant Committee of the RHS understand the range of plants which are actually being grown around the country - and under what names. Please don't send plants! Just email pictures.

Thank you! I'll report back here as we continue the research.