[This is an update on a post which first appeared on my Simply Gardening blog which is for British gardeners. But this is such a great plant I thought that readers around the world would also like to hear about it.]

Perhaps the most stunning new sweet pea to emerge in recent years has been ‘Erewhon’ (above, click to enlarge). Developed in New Zealand by Dr Keith Hammett, ‘Erewhon’ is what is known as a reverse bicolour. Most bicoloured sweet peas have the standards (the upper petals) darker than the wings (the lower petals) – but not the other way round. But in ‘Erewhon’ the wings are darker than the standards. In addition, the vivid and penetrating blue colouring of the wings is exceptional. So, how did it happen?

Keith worked on reverse bicolours for twenty five years before his first, ‘Leading Light’, in pink and lilac, appeared in 2006. (This is no longer available.) But with the impact of genes from the relatively recently discovered Lathyrus belinensis, from Turkey, (right, click to enlarge) he was able to intensify the colours. This development was a by product of using L. belinensis to help develop a true yellow sweet pea; that quest for that continues…

The result is ‘Erewhon’. Erewhon is the classic Samuel Butler novel of 1872, pronounced E–Re-Whon (not Air-One); the first part of the book features a fictional account of Butler’s travels in New Zealand. The name is an anagram of nowhere. 

In this captivating sweet pea the standards are pinkish lilac, with darker veins, and the wings are an amazing piercing blue. This is a Grandiflora type, like the old heirloom sweet peas which we always grow for their unsurpassed fragrance. In developing this completely new variety Keith ensured that the classic sweet pea scent is retained. And it has all the usual sweet pea qualities, reaching about 6ft/1.8m in height and with three or four flowers per stem.

I saw ‘Erewhon’ in a number of different places around the country this summer, and it always looked and smelled amazing. Better order it before stocks of seed run out. And why not try the pretty little Lathyrus belinensis as well?

Seed of sweet pea ‘Erewhon’ is available in North America from Annie's Annuals and from Burpee

Plants and seed of sweet pea ‘Erewhon’ is available in Britain from Simply Seeds and Plants.

Plants of of sweet pea ‘Erewhon’ is available in Britain from Hayloft Plants

Seed of sweet pea ‘Erewhon’ is available in Britain from English Sweet Peas, Owl’s Acre, and from Thompson & Morgan

Seed of Lathyrus belinensis is available in North America from Thompson & Morgan

Seed of Lathyrus belinensis is available in Briatin from Owl's Acre and from Simply Seeds and Plants.

I just thought you might appreciate an update on all my online offerings over the last two months. They all start with the new webpage for my latest book - Powerhouse Plants: 510 Top Performers For Multi-Season Beauty. More about this book here soon.

Transatlantic Gardener
Just take a look at the links in the sidebars to check out recent posts on this Transatlantic Gardener blog

Simply Gardening blog (mainly for Brits)
Here are my blog posts from the last two months on my Simply Gardening blog

Two ways with spring bulbs, in containers
Sweet pea ‘Erewhon’: Breakthrough new variety
Tulips and daffodils, happy together
Daffodils, naturally
Easy cut flower perennials
The blackberry for kids (and for grown ups)
Lettuce without disease
If you only grow one raspberry variety…
Great taste, no thorns, no disease: a Great British gooseberry

Royal Horticultural Society New Plants blog
My RHS New Plants blog has covered a wide range of exciting new plants.

Clematis ‘Sweet Summer Love’: Combines fragrance and colour
Agastache ‘Blue Boa’: colourful and drought tolerant
Euonymus japonicus ‘Happiness’: Bright new colourful evergreen
Hosta ‘Purple Heart’: red leaf stems and colourful flowers
Olearia ‘Moondance’: New variegated evergreen shrub
Tomato ‘Black Opal’: New black cherry tomato from Dobies and Suttons
Calibrachoa ‘Superbells Lemon Slice’: Sparkling new bicolour
Digitalis Dalmatian Series: gorgeous colours, quick to flower
Alstroemeria ‘Indian Summer’: Dark foliage and fiery flowers
Echinacea ‘Cheyenne Spirit’: Sparkling new six colour mixture
Kale ‘Black Magic’: An improved Cavalo Nero
Phlox Paparazzi Series: New from Hayloft Plants

Top Ten RHS Award of Garden Merit plants
Continuing my series on Award of Garden Merit plants of special types and for special uses.
Evergreen perennials
Climbers and wall shrubs

The latest RHS Award of Garden Merit plants
My choice of the latest plants to be given the Award of Garden Merit.
Broad bean ‘Witkiem Manita’
Lespedeza thunbergii subsp. thunbergii

One of the unexpected stars in the garden this summer was an American native weed – jewelweed, Impatiens capensis. I’d seen it growing by creeks in this area, of course, and I always thought it was an attractive plant with its sparkling, red-spotted, orange flowers (left, click to enlarge). But the nearest wild plants I’d seen were a mile or two away, so I suspect that the seeds that produced the plants in our garden came in on my boots.

So: “What was it doing growing in your garden?” I hear you cry. “It’s a weed!” Well, when I spotted a seedling, just a few inches high, I thought I’d not pull it out as a weed but just let it do its thing – the flowers being so pretty. That first year, we had just a seedling or two which, in a dark and dry part of the garden, produced just a couple of small spindly plants. But, every year, it seeded. We pulled out most of the seedlings - which is easy when they’re small - and left one or two to flower.

This year we never even spotted the seedling between shrubs outside the guest room window until it emerged alongside the indispensible Physocarpus Coppertina (‘Mindia’) and behind Weigela Wine and Roses (‘Alexandra’). It flowered for months, never dominating, but always there. Always sparkling.

Of course, now we’ve let that one plant grow to almost 6ft/1.8m high, it will have produced so much seed that next year there’ll probably be hundreds of seedlings. And, again, we’ll pull most of them out and leave just one or two.

But it just shows how an ignored and unadmired native weed can add colour and character to the garden tapestry – if we just open our eyes to its beauty.

You can buy seed of Impatiens capensis from Horizon Herbs in North America, and from Plant World Seeds in Britain.