Transatlantic Plantsman

How do you know if a plant is hardy?

I’ve been thinking the muddled issue of hardiness zones this week – and muddled they are indeed. These are ratings that classify plants according to the climatic conditions they’ll tolerate – in particular, how much winter cold they’ll take. Maps divide the world zones according to the prevailing conditions.

American gardeners use them all the time, and for their interest here’s a map of Britain (click to enlarge) split up according to the USDA system widely used in the USA. British gardeners will find the, of course, far more complicated US map below.

The problem is this: At a time when plants (and sometimes their coloured labels) move around the world so quickly, when most plant and garden books are published internationally and with everyone looking up plants online wouldn’t it be more helpful to have one single system?

Britain The RHS has a four zone system (some use an extra zone for parts of Scotland) based not on minimum temperatures but on the growing conditions plants require. The RHS also often cites the actual temperatures plants will tolerate or uses a system of symbols.
Europe Here the USDA system is sometimes used but the European Garden Flora uses its own seven zone system based mainly on minimum winter temperatures.
United States There are three systems. The USDA (United States Department of Agriculture) system of eleven winter hardiness zones and the similar National Arbor Day Foundation system are based on minimum winter temperatures. There’s also the completely different 45 zone Sunset system, used almost entirely in the west, that also takes summer heat and other factors into account.
Canada Agriculture Canada has created an eight zone system based on minimum winter temperatures, summer rainfall, snow cover and other factors.Australia Here they use a modified version of the USDA system.

I could go on…

So I’m wondering – does it matter? Well, you know what I think. I write online and my books are published all over the place – it would be simple to use just one system.

What do you think? One system for everyone or each to their own? Keep in mind that any system is only going to provide a rough guide.

Lectures and book signing

A little flurry of events coming up...

20 March (USA)
Kaleidoscope of Color Garden Show
Homestead Gardens, Davidsonville, MD
12pm New Perennials - lecture
I’ll be presenting my look at new (and one or two undiscovered) perennials.
Also featuring at the show: Katy Moss Warner, President Emeritus of the American Horticultural Society

20 March (USA)
The Orchid Show
New York Botanical Garden
3.30pm Book signing in the Shop in the Garden
my wife judywhite will be signing copies of her new book, Bloom-Again Orchids, and demonstrating how to pot orchids

21 March (USA)
Kaleidoscope of Color Garden Show
Homestead Gardens, Davidsonville, MD
3.15pm New Perennials lecture
A second chance to see my presentation on new (and one or two undiscovered) perennials
Also featuring at the show: Katy Moss Warner, President Emeritus of the American Horticultural Society

April 16 (UK)
Hardy Plant Society (Staffordshire Group)
Little Haywood Village Hall, Little Haywood, Stafford,
7.30pm Hellebores and Friends - lecture
I’ll be talking about and showing hellebores old and new and plants to grow with them in the garden.


Note to burglars: yes, we’re both away for the weekend of 20/21 March – but you won’t want to mess with our cat sitters!

Japanese barberry - on the march

I looked out of the window yesterday and discovered why Berberis thunbergii, the Japanese barberry, is turning up all over the place across the woods here in Pennsylvania, and elsewhere. In some areas it’s a menace.

I was just putting some washing in the machine, and I looked thoughtlessly out of the window at the strip of Japanese barberry we have growing along the path at the side of the house and there they were – a dozen or more robins (American robins, that is - check out the very different British and American robins) stuffing themselves on the barberry berries which had held right through this snowy winter till this week.

Five minutes later they were all gone, the birds and almost all the berries – and that’s the point. As the robins move on through the woods, the seeds in their droppings fall as they go. The acid in their digestive system will have primed the seeds to germinate, and germinate they will. And they’ll start to dominate the understory in our forests.

I’ve kept that one row of barberries, just so I can see how much they spread nearby: hardly at all, in fact. But apart from the occasional chipmunk clambering up the stems I’ve rarely seen anything actually eat the berries. Until now. And it only takes one little flock, on one day… and the Japanese barberries are everywhere. This picture was taken just six or seven miles away (right, click to enlarge).

BUT!! Let’s just be clear: if the numbers of deer in the forest had not risen to such an overabundance and if they hadn’t plundered the native flora so catastrophically then the Japanese barberries (which the deer never seem to eat) wouldn’t have had it so easy.

We've had the tree guy in

Since the last snow fell - what, about a week ago - someone's been doing a job on one of our birches.

I saw this in the distance across in the woods and couldn't quite see what was going on (click to enlarge). So I went to investigate (trudging through a foot of snow - where are those snowshoes?)

To be honest, we like to leave the dead trees in place for exactly this reason. The grubs munch their way through the dead wood and the pileated woodpecker, (right, click to enlarge) all 18in/45in of him or her, chips away at the wood to munch on the grubs.

But that's big pile of chips to create in just a few days. They come to the bird feeders sometimes, and it's a treat to see them, they're just so huge! And they can do an elegant flute-like job on some trees.

Oh! And a red-tailed hawk just flew by my window and sat on a branch... Not a squirrel in sight, needless to say. They're probably all quivering in the woodpile.

Spring... at last...?

And about time too – we have some flowers.

Quite a lot of flowers, actually – but all on the one plant. While the hellebores and snowdrops are still under a foot or more of snow, the hamamelis is in full flower. So it must be spring. But not another flower in sight.

And this morning we had a red-winged blackbird on the feeder. “It’s a sure sign of spring when the red-winged blackbird returns to the marshes,” says the book (Birds of Pennsylvania Field Guide). Well, tough on the poor blackbird. The marshes are still frozen solid.

Actually, I’m worried about that hamamelis – Hamamelis x intermedia ‘Pallida’. It seems to me that the petals are little bit short, and not quite pallid enough – and it doesn’t really have as much scent as I remember. “Hamamelis x intermedia ‘Pallida’ probably has the strongest scent” says last year’s blog post from RHS Rosemoor. Not this one, it doesn't.

Well, if you must buy shrubs in a sale…

And I wonder what's going on under all that snow? It's basically melting from the underneath so the soil must be warm enough not only to melt snow but encourage a little growth... I'm intrigued.

Great advice on macro photography - from the expert

Macro photography wizard Alan Detrick, author of Macro Photography for Gardeners and Nature Lovers, now has a series of podcasts available from his publisher, Timber Press, in which he reveals how to take great close-up images.

He discusses techniques and equipment and ways to think about macro photography in the accessible way that he’s developed in years of teaching photography workshops.

Well worth a listen, it comes in six parts. Just click to listen.

Alan Detrick’s macro photography podcast – part one

Alan Detrick’s macro photography podcast – part two

Alan Detrick’s macro photography podcast – part three

Alan Detrick’s macro photography podcast – part four

Alan Detrick’s macro photography podcast – part five

Alan Detrick’s macro photography podcast – part six (coming soon)

And check out Alan's fascinating blog, which is packed with good advice, plus the gorgeous macro images on his website.

And of course you can order the book.

In North America order Macro Photography for Gardeners and Nature Lovers from amazon.com

In Britain order Macro Photography for Gardeners and Nature Lovers from amazon.co.uk

Botanical thrills

The Journal of the Botanical Society of the British Isles (BSBI) arrives. Always intriguing. This issue features, apart from the arcane (but valuable) botanical stuff like eight pages on the identification of two hybrid Juncus (rush) species, something much more exciting.

At their Annual General Meeting in June there’ll be a demonstration of “DNA extraction from a fruit smoothie – using only household reagents”! Sounds great. Actually, it turns out that this is not a unique idea but still – impressive, I’d say. All we need now is advice on how to determine the cultivar of strawberry in the smoothie using tools found in the average suburban garage.

But there are two other valuable features of this issue. One is the list of new plant records for the British Isles – ten and a half pages of them, six pages of which are records of newly introduced species. [For US readers, the area of the British Isles is about the same as that of Michigan, the 11th largest state.] It’s invaluable that discoveries of individual species, sometimes just single plants like the Berberis darwinii found on Sark in the Channel Islands, are recorded as this vital information is crucial to our understanding of the spread (or more often the lack if it) on non-native species. News of similar, state-by-state, records in the US would be appreciated.

Finally, there’s a ten page paper from Michael Braithwaite, President of the BSBI, on how successfully the BSBI has recorded the spread of non-native plants. I may well come back to this important piece another time but one thing jumps out: when referring to non-native plants he encourages us not to use the term “alien” but instead to call these plants “incomers… to avoid being judgmental.”

Here in the US, the term “alien” is routinely used - sometimes, I have to say, with the intention of being judgmental.

Online on the road

Sorry, been a bit quiet here recently.

We take it for granted that we can get online. But traveling about Britain recently it’s been, well, tricky. Fine at home, DSL line. No problem. Bought a Vodafone wireless dongle so I could get online anywhere over the mobile phone network. Seemed the obvious solution. But.

At Mum’s retirement community in suburban Surrey, on the southern edge of London, the connection is so slow that websites won’t even load and it’s impossible to know if email has gone off or not. This is an area packed full of heavy mobile phone users. Ten miles away, at the RHS Wisley Garden – nothing: no signal at all. Nothing. At the nearby railway station – we’re back to half a bar.

So, I stop at the service station on the motorway. Free wireless internet! Except that after ten minutes they bump you off the website site you’re browsing – or, in my case, the blog post I’m half way through writing – to make you log on again. Bye bye blog post. At the RHS London Flower show the other day, from where I was expecting to post about all the sparkling primroses and snowdrops and hellebores - the Vodafone  dongle connection is so slow that it’s completely impossible. Ah - but the Horticultural Halls have wireless internet access – it’s £5/$7.60 for one hour! Not a day, an hour. I’m not paying that. The rather resigned man on reception says he’s had lots of complaints. OK, the RHS is hard up – but why price it so that no one in their right mind would ever buy an hour of access.

Vodafone is hoping for an exclusive on the iPad in Britain. My nephew in New York didn’t buy an iPhone because the AT&T service in the city is so terrible. Here’s the thing. If the government nationalized the tower network, or handed it all over to one company, and let all the phone companies use all the towers – then everyone would have access to the best possible connections. The mobile phone companies could then compete on other aspects of their service. And I could post pictures of the hellebores and primroses at the show – from the show. Instead of from back here in Pennsylvania.

Oh, yes - the plants! One of the splendid new British bred  Belarina Series of double primroses, 'Belarina Cream', developed by David Kerley who also created the Tumbelina double petunias. And the 'Briar Rose' hellebore, an unlikely cross between H. niger and H. vesicarius, was created by Kevin Belcher at Ashwood Nurseries.

Kew's Temperate House is falling down

News today that the largest Victorian glasshouse in the world may have to close as it will soon be falling down.

An independent review of the Royal Botanic Gardens, Kew, reveals that The Temperate House is in need of prompt restoration without which it could pose safety risks to public, and staff, in the next two or three years. The report also points out that there’s a huge backlog of other maintenance and repair on Kew’s buildings that will cost £80million/$125million to put right.

So, basically, they have not been spending what they should on regular maintenance. Someone needs a bollocking seems to have been derelict in their duty, over the years.

Twice as large as the more famous Palm House at Kew, The Temperate House was completed in 1899 and is home to a huge collection of plants which are too tender to be grown outside but which don’t require the humid and hot tropical conditions of The Palm House.

As it happens, I remember the last time The Temperate House went through a dramatic restoration. For what seemed like years in the late 1970s, I think, most of the plants were moved out and hard hats were compulsory. Clearly, this spectacular building, with its high observation platform from which to look down on the plants, has been neglected since.

But where’s the money to come from? Not, please by upping the entrance fee. At present it costs £13/$20 to get in – that’s for just one person. With car parking on top. Enough to deter a huge number of people from visiting. And take a look at this video to see how much there is to see.

Kew Gardens HD from Philip Bloom on Vimeo.

Shows my age again, I suppose, but when I was a kid it cost just a penny to get in and collecting the money cost more than people paid. There was even a plan to close the gardens to the public altogether – Kew is a scientific institution, after all - and so make significant savings on all that has to be done to accommodate the visiting public. Instead the price went up – and up and up.

So what’s the answer? A tricky question in these hard times. The report suggests that grants have not kept pace with the increased rate of grant help to museums – good – and that Kew should raise more than the existing, very impressive, £23.4million/$36.5million from commercial activities. The trick is to balance commerce and science – even assuming Kew can compete successfully for the commercial revenue being sought by so many other venues.

Looks like grants, then. And don’t forget that increased grants not only means repairing buildings, it means hiring more people. Which with unemployment so high, is exactly what we need. Kew’s own stimulus package, if you like, both to restore the gardens and provide jobs. Sounds like a good deal to me.

Misleading magnolia

Magnolia sieboldii is a lovely shrub, or even a small tree. But don’t expect it ever to look like this – unless you cut the branches off your flowering tree and stuff them into a pot. As seen here. This is not a patio plant, it can be a 30ft+/10m+ tree!

What’s more, although it’s one of the magnolias which flowers when quite young – usually when about five or six years old – it never ever flowers at the size seen in this picture from Britain’s Daily Telegraph’s online garden shop.

Neverthless… Magnolia sieboldii is one of the finest of all magnolias, and fragrant too. Just be sure to plant it in moisture retentive, acid soil. And not in a patio pot!