The good people at Proven Winners and Spring Meadow Nursery recently sent me a new buddleja (butterfly bush) to try in the garden. Lo & Behold Blue Chip is very dwarf, 2-3ft, and certainly looks promising. The fact that no buddleja I’ve tried here in zone 5b has ever survived the winter doesn’t discourage me – this is a complex inter-specific hybrid so may just prove hardier. It’s also unusually dwarf which, frankly, excites me rather less. I always think buddlejas are at their best at 6-8ft tall and arching over the border – but I’m open to persuasion. Mainly, I just want one that’s hardy here..

But buddlejas are controversial. Last year the National Zoo (part of the Smithsonian Institute in Washington) chose Buddleja as a Plant of the Month, for its enormous value in attracting butterflies and other beneficial insects. After protests from the invasive plant lobby, it changed its mind saying: "We do recognize that Buddleia, while it attracts butterflies, is an invasive exotic that we should not be promoting. We have removed that article, replacing Buddleia with the native flowering dogwood."

“Invasive exotic”? Not here it’s not. Here in zone 5b we can’t get buddlejas through the winter yet the National Zoo daren’t even suggest we should try. It quakes after receiving a few complaining emails and changes its mind.

Here’s the thing. The USDA cites B. davidii as growing in just fifteen states across the country… The National Parks Service reports it as invasive in eight states. But just because a state reports it as invasive doesn't mean that every appropriate habitat is engulfed. It could mean that one person reported the plant as invasive at one site in the state - once. The National Parks Service reports buddleja as invasive in Pennsylvania but in our part of the state it’s not even hardy, let alone invasive.

In Oregon, while the Oregon Nursery Association was in constructive discussions with the state Department of Agriculture about buddleja whether nurseries should be selling it, and as they were close to an agreement that satisfied everyone’s concerns, the state legislature jumped up and banned all sales and production of B. davidii and all of its cultivars, regardless of whether the cultivar is invasive, non-invasive or even sterile. The law takes effect in six months. So much for negotiation. (That new Lo & Behold Blue Chip, by the way, is almost completely sterile – but presumably as it’s not a cultivar of B. davidii it’s not covered by the ban.)

Japanese knotweed is a menace over much of the country, no one disputes that. Buddleja is not – and never will be – as much of a problem. But I resent the notion that I shouldn’t grow it, even as a temp-perennial for summer containers. And banning it in the middle of negotiations just fires up further resentment. So can we just develop a sense of proportion here? And educate the American people instead of banging them on the head with a hammer?

I have a piece in Britain's Daily Telegraph newspaper today... on recent developments in border phlox (Phlox paniculata). You can read it here.

You can read my piece about the new plants at the Chelsea Flower Show here. And see my full list of all the new plants unveiled at Chelsea here.

And my profile of the most influential writer on vegetables of our times - Joy Larkcom - is also  available online. You can read it here.

You can also read my choice of the Top Ten New Perennials selected for the Daily Telegraph here. Be sure to click on the In Pictures: Top 10 new perennials link at the top of the page to see a slide show of all ten of my picks.

You can also read my previous article on Clematis cirrhosa here

 Last year you may remember that judy and I found a brightly variegated form of Alchemilla mollis. Here’s the picture again (don't forget, click on it to see an enlarged version), you can read the story here.

Well, it was planted inside a fence to keep out the deer and I was eagerly looking forward to seeing if it retained its variegated foliage this year. I looked, the plants around were coming to spring growth – no signs of the alchemilla emerging. I started to check it almost every day… Hmmm… nothing. I resisted the urge to poke at the crown.

And now this is the situation – nothing. I’m resigned to its passing. No plant. It’s dead. Why, I don’t know. Perhaps I should have split it straight away and planted the pieces in different sites.

Next time I find something promising l’ll split it straight away and plant the pieces in different places!

New perennial coreopsis seem to be popping up everywhere and here are some more – twenty five more from the cross-pollinating paintbrush of Darrell Probst, famous for his epimediums. Click on the picture to see a large image. His new Big Bang Series is included here… What an amazing collection!

Of course, as many gardeners have discovered, “perennial” is a relative term when it comes to coreopsis. The more unusual colours are derived from annual varieties which bring a short life as well as new colours so varieties like ‘Autumn Blush’ and ‘Limerock Ruby’ tend to give one summer of colour and no more in many gardens. That’s not necessarily a bad thing, prolific summer container plants are invaluable, we just need to know.

The Big Bang Series, though, is bred to be hardy in zone 5; it’s now being tested in zone 4.  The first to be introduced, ‘Full Moon’, with 3in/7.5cm flowers in clear pale yellow, is now available by mail order in the US. Expect ‘Redshift’ to be available before too long, its 2in/5cm flowers open creamy yellow with a red ring around the eye and in cooler weather the red colouring becomes more dominant.

Also on the way is ‘Sienna Sunset’, a sport of the popular ‘Crème Brûlée’ in an unusual burnt sienna shade.

Also new is ‘Lightning Flash’, a form of C. tripteris, with bright yellow foliage and yellow flowers - though at 6ft/2m tall it’s a rather a different creature from most coreopsis; it should be a dramatic back-of-the-border plant. It should be available in the US soon, and later in the UK. ‘Curiosité Chartreuse’, from Europe, looks similar to ‘Lightning Flash’ but its appearance in nurseries is a little more distant. However, Beth Chatto had a similar yellow-leaved form which has been around in Europe for about ten years but never appeared in nurseries. All three are probably the same.

But as more and more of these coreopsis appear on the market - some tough as nails, some more like annuals for summer containers - we need breeders and nurseries to be open and realistic about the hardiness of these plants. It’s not that we won’t grow those that are less hardy, we just need to know so that we can grow them in an appropriate way and our expectations are not dashed.

There’s been a recent innovation at the Royal Horticultural Society’s trials at Wisley – the judges give the awards, but visitors now also get to vote for their favorites.

Clearly this would be a little impractical with, say, carrots which have to be dug up and tasted. But voting took place for tulips and hyacinths grown in the open ground this spring and there will be more opportunities during the summer and fall.

Top of the list of tulips was ‘World Expression’ with ‘Dordogne’ second out of the 196 entries on trial with RHS Award of Garden Merit winner ‘Maureen’ only getting one vote! Of the hyacinths, ‘King of the Blues’ came out top with ‘Blue Jacket’ second out of twenty seven entries on trial.

Voting is taking place for garden pinks now, while buddleias will follow. And if you’re visiting Wisley and look for the signs by the Wisley gate later this month. There will be opportunities to taste the raspberries on trial and vote for the tastiest – but only on days when crops are available.