Annuals and seasonal plants

Winter weirdness in the banana border

Winter banana protection at the RHS Garden, Wisley. Image ©GardenPhotos.comOn a quick gallop around the Royal Horticultural Society’s garden at Wisley, in Surrey south of London, last week I came across what from a distance looked like a rather old-fashioned artistic installation. But no, it’s the bananas in their winter livery (click the images to enlarge).

Growing bananas outside in Britain (zone 8) is a dicey business – so often the winters are just too cold. So the banana plants in the subtropical borders, across the lawn from the restaurant, are wrapped in fleece and hessian (burlap to Americans) to protect them.

You can tell from the way that the stalagmites are grouped that young plants springing from suckers are being protected alongside larger specimens so the technique must have worked in the past.

We all like to try to keep plants that are borderline hardy through the winter: well, this is how it’s done.

Protecting plants in the subtropical borders at the RHS Garden, Wisley. Image ©GardenPhotos.com



New colors in bidens for baskets

Bidens 'Goldeneye'Bidens, tickseed, is not a plant that leaps to mind when we first think about annuals for baskets and other patio containers. It’s just not. A few years ago Bidens ferulifolia was touted as a useful basket plant but although its bright yellow daisies look good against the slender dark green leaves, and it develops an appealingly billowing habit, it makes such a big plant that almost everything else is overwhelmed.

But things have changed, and new varieties from two different sources have ensured that we all take another look at bidens.

In Britain, the Thompson & Morgan breeding program has developed a series of varieties which are much more neat and compact than Bidens ferulifolia, come in new colors and flower forms and which are also more prolific.

There are eight varieties in their Pirates Series with ‘Golden Eye’ (above, click to enlarge) probably the pick, its golden centered white flowers are outstanding. There’s also the pure white ‘Pirates Pearl’, the double yellow ‘Pirates Booty’ as well as single and semi-double yellow varieties. Unless your containers are huge, all are improvements on Bidens ferulifolia.

Then from Japan comes the Hawaiian Flare Series. No pure yellows at all in this series, which concentrates on orange and red shades and color combinations. The plants are larger than those in the Pirates Series with a semi-trailing habit and are very prolific. The first three in the Hawaiian Flare Series are ‘Hawaiian Flare Orange Yellow Brush’ (below right, click to enlarge), with gold-centered orange flowers, ‘Hawaiian Flare Orange Drop’ (below left), which is the reverse with vivid orange flowers and yellow-tipped petals while ‘Hawaiian Flare Red Drop’ (below center) is soft red in color. More are on the way.

These are all just starting to appear on websites, in catalogs and in nurseries. In Britain try Mr. Fothergill’s, Brookside Nursery and good garden centers. In North America try Burpee and good local retail sources, across the Pacific North West plants are also available in nurseries supplied by wholesaler Log House Plants.
Bidens ‘Hawaiian Flare Orange Drop’ (left), ‘Hawaiian Flare Red Drop’ (center) and ‘Hawaiian Flare Orange Yellow Brush’ (right)



Bee-friendly Himalayan balsam

Three of the colours seen in Impatiens glandulifera, Himalayan balsam, in Northamptonshire. Images ©GardenPhotos.com
Himalayan balsam, Impatiens glandulifera, is a common plant of British riversides, pond margins and other wet places and is always said to be too invasive for us to be allowed to grow. It looks as if it’s smothering everything else where it grows, so it’s banned. It can be a lovely plant, so not being allowed to grow it is unfortunate.

On my recent short visit back to England I saw it along the River Nene in Northamptonshire (along with the American native Imaptiens capensis), by the Wey Navigation Canal and River Wey in Surrey and in other waterside places. Some stands of it looked dense and were well over 6ft/2m high.

Impatiens glandulifera, Himalayan balsam, growing by the River Wey in Surrey. Image ©GardenPhotos.comBut the most striking feature was the colours. The flowers varied from cherry red through various purplish and pink shades, including some pretty bicoloured forms, to almost white. Years ago I used to grow a pure white form called ‘Candida’ (with none of the anthocyanins that bring the red and pink colouring); it’s very pretty, but those pale flowered plants I came across this year all had a faint blush of pink.

Also known as policeman’s helmet from the similarity of the flower shape (though not the colour!) to the helmets worn by London policemen, it’s listed as a noxious weed in three US states though it’s not yet found in most country.

However – is it really that bad? Needless to say Ken Thompson gives us the low down in his latest book, Where Do Camels Belong? The Story and Science of Invasive Species. Himalayan balsam in Britain, like purple loosestrife (Lythrum salicaria) in North America, turns out to be an example of a plant that looks as if it’s smothering everything to extinction while the basic science tells a different story.

Dr. Thompson reports that a large scientific study that compared areas that had been invaded with similar habitats that had not concluded that “it (Himalayan balsam) does not represent threat to the plant diversity of invaded areas”. But although one visual assessment turns out to be misjudged, another turns out to be valid. The late flowering of Impatiens glandulifera provides valuable food for bees when few other plants in its favoured damp habitats are flowering. So it’s actually quite useful as well as attractive – so it’s shame that we’re not supposed to grow it.


Transatlantic touch-me-not

ImpatienscapensisCloseIt’s always intriguing to find a plant that’s native near our American home in Pennsylvania growing near our English base in Northamptonshire (and vice versa) and the other day a stroll by the River Nene not far from our Northamptonshire house provided an enjoyable surprise. Spotted touch-me-not or jewelweed, Impatiens capensis, was growing on the bank (below, click to enlarge).

There were only a few patches, all grouped near each other, and I wondered for a moment if I myself had inadvertently introduced it on my shoes as perhaps I did in Pennsylvania when it suddenly it turned up in our garden. I walk this same stretch of river every time I’m back in England.

Mike Grant, editor of the Royal Horticultural Society magazine The Plantsman, pointed out in a comment on my piece about this plant turning up in the garden that “it has the distinction of first being recorded in the wild by the philosopher, John Stuart Mill Impatienscapensis(in Surrey in 1822)” and it is now well established in Britain, though mostly a little farther south and west from where I came across it.

In fact, we’d been thinking that perhaps we have the wrong native Impatiens in our Pennsylvania garden. Touch-me-not, Impatiens pallida, is bright yellow instead of red-speckled orange and would show up more effectively from a distance. Tomorrow I’m going to collect some seed from the plants that I’ve seen a few miles from our PA home. In which case look out for it in Northamptonshire a few years from now!

Thoughts on another non-native Impatiens species next time.


A field full of Black-eyed Susans

Black-eyed Susan (Rudbeckia hirta) growing in the Delaware Water Gap National Recreation Area. Image © GardenPhotos.com
There I was, driving along counting all the European plants growing - and often looking very attractive - along the Pennsylvania roadside when in the distance I noticed a whole field of orange. In this part of the world it could only be one thing: Black-Eyed Susan (Rudbeckia hirta). And so it proved, a large field covered from edge to edge in R. hirta, with a scattering of fleabane (Erigeron annuus).

This is in the Delaware Water Gap National Recreation Area, a park ripe with alien plants as well as natives and also very rich in bird life. But acres and acres of rudbeckia? It didn’t look natural. The park people had a hand in that, I’m sure, they must have sown seed. But it looks spectacular.

There were also three interesting features about the uniquely colorful field. Firstly, I spent two half hours, on two different sunny days, walking through the field and looking at the plants and I did not see a single insect of any kind feeding on the flowers. Not one.

And secondly, the flowers varied in shape noticeably: some flowers were very starry with narrow ray florets (the petals) and some much more full with broader rays; and many were in between.

RudbeckiaHirtaCloseUp-GPAlso, I noticed that on all the plants the flowers were bicolored: dark yellow-orange at the base and a paler tone at the tips (left, click to enlarge). That two-tone coloring is a feature of many garden varieties but the Flora of North America – the most authoritative work on North American native plants - is very specific: it says that the rays are “usually uniformly yellow to yellow-orange”. I’ve since checked other plants in the area and they’re all two-tone.

The Flora of North America also says: “or with a basal maroon splotch, sometimes mostly maroon”; I’ve never seen a wild plant with maroon flowers in the wild. But it shows that the rusty coloring of many garden varieties and the development of the first red flowered form 'Cherry Brandy' (below, click to enlarge) are based on an inherent genetic capacity for darker shades.

So, naturally, many people want to grow this colorful plant in their gardens. But, as a friend said to me the other day: “We keep planting them, but they never come back the next year.” The reason is that they’re biennial, and they die after flowering and you either have to sow more seed or hope they self sow. If you want a perennial form, grow Rudbeckia fulgida.

Rudbeckia hirta 'Cherry Brandy'. Image © Johnsons Seeds
UPDATE: And here's a view of the field a few days later from the top of the nearby escaprpment, hundreds of feet above.

Field of Rudbeckia hirta (Black-eyed Susan) seen from the overlook above Cliff Park, Milford, PA. Image ©GardenPhotos.com


Multicolored newcomers

HibiscusSummerificCherryCheesecake-700Every year the good people at Proven Winners send us some new plants to try. This year’s parcel arrived recently and there are two plants that look especially tempting so I thought I’d mention them straight away – before they’re even planted (torrents of rain today).

Hibiscus ‘Cherry Cheesecake’ (left, click to enlarge), in their Summerific® Series, is nothing if not dramatic, and gorgeously colorful. It’s a hardy perennial hibiscus with flowers 7-8in/20cm across set against dark green maple-like foliage on plants about 4-5ft/1.4-1.5m high. And it blooms all the way up the stems, not just at the tips.

It's tough, too; a few years ago I saw the field in Michigan where breeders Walters Gardens test all the their new seedlings; it’s cold, plants are hardy to zone 4/-34C. For British gardeners it’s more the summer that’s the problem: is it hot enough for these plants? Well, we’ll soon see as a British grower has been testing the whole Summerific® Series and if they thrive we’ll see all four varieties in nurseries in a year or two. In North America, you can order Hibiscus ‘Cherry Cheesecake’ from the Vermont Wildflower Farm.

The other plant that caught my attention amongst this year’s Proven Winners samples is Calibrachoa Superbells® ‘Frostfire’ (below, click to enlarge). There have been some gorgeous multicolored calibrachoas introduced in recent years, I especially like Superbells® ‘Lemon Slice’, which was such a success last year, and also Superbells® ‘Tangerine Punch’. In ‘Frostfire’ the white flowers have a yellow throat streaked in red. Unique – but not available until next year.

These newcomers have something in common: the flowers are multicolored, white and cherry red, or white and yellow and red. This gives you a clue as to what to grow with them. Choose plants with white or red flowers alongside the hibiscus, and plants with white yellow or fiery red flowers in a basket with the calibrachoa. That’s the way to create a harmonious look.
CalibrachoaSuperbellsFrostfire-700



New begonias - flowering varieties

Begonia Million Kisses Elegance, Amour and Blissful. Images ©GardenPhotos.com and ©Ball ColegraveLast time I took a look at new foliage begonias from the US, that I expect British gardeners will be seeing soon. This time – it’s the other way round… new British begonias that North American gardeners should have on their watch list. And while so many of the new US begonias come from one creator, the same is true in Britain.

In recent years Britain’s Fred Yates, from Cheshire in the northwest of England, has introduced more fine new flowering begonias than anyone else - starting with his exceptional Million Kisses Series (left, click to enlarge). These hybrids derived from Begonia boliviensis feature single flowers, in seven colours – and in vast quantities. The blooms come all summer long and into the autumn. Amour (‘Yamour’) is red, with dark leaves; the latest, Blissful (known as Cute Kiss Pink in North America), is a blush and pink bicolour; Devotion (‘Yafev’) is red; Elegance (‘Yagance’) is a white and pink bicolor; Honeymoon (‘Yamoon’) is yellow; Passion (‘Yabos’) is orange-scarlet; Romance (‘Yamance’) is salmon pink. You’ll be amazed at how prolific and colourful they are.

Three more from Fred Yates which I especially like are ‘Glowing Embers’, Sherbet Bob Bon (‘Yabon’) and Cherry Bon Bon (‘Yachbon’). All have a neat, semi-trailing habit and never become straggly and thin.

‘Glowing Embers’ is simply gorgeous, its combination of rich dark foliage backing a long long season of vivid, fiery orange single flowers. In America it's known as ‘Sparks Will Fly’. Sherbet Bon Bon has two tone yellow flowers with pink tints and a neat double centre while Cherry Bon Bon has cherry pink flowers with a golden tint to its double centre.

Two British-bred seed-raised begonias that seem to be doing well not only in Britain but in parts of the US with hot summers are the Ikon Series. These vigorous and robust hybrids make substantial plants which take heat and drought once established, There are only two so far, both with pink-and-white flowers: ‘Ikon Blush White’ has red-backed green leaves while ‘Ikon Bronze’ has bronze foliage.

Finally, Thompson & Morgan have launched a British campaign entitled The Big Begonia Revival. Frankly, I thought the revival was well under way but T&M are making the most of it. They’ve been breeding fragrant begonias since 2006 and now have their Fragrant Falls Improved Series, in three colours: ‘Apricot Delight’, ‘Lemon Fizz’ and ‘Rose Syllabub’ (below, click to enlarge). All are double, all are fragrant and all have compact, semi-trailing growth and are ideal in baskets and trailing over the edge of large pots. You can read T&M’s fascinating account of the development of scented begonias, from 1886 right up to their latest own introductions.

All these begonias are available in Britain this year though some may take a little hunting out. Almost all be available in North America too, so get Googling. North American gardeners will have to wait till 2015 for the three colours in the Fragrant Falls Improved Series.
Begonia Fragrant Falls Apricot Delight, Lemon Fizz and Rose Syllabub. Images ©Thompson & Morgan



New begonias - foliage varieties

Begonia Garden Angel Series. Images ©TerraNova NurseriesThere are about nine hundred species of begonias, so it’s hardly surprising that they’re so important to gardeners. And on both sides of the Atlantic new begonias are arriving fast. In the States, it’s mainly foliage types to grow outside in containers, or even as hardy perennials; in Britain it’s flowering varieties for containers, many with blood from B. boliviensis, that are making an impact.

I think that each country should grow more of what the other is already growing. So, today, I’m going to have a quick look at the new foliage types and next time I’ll feature the new flowering types.

So new styles of foliage begonias for use in patio pots and the open garden have been pouring out of Terra Nova Nurseries in Oregon, the world’s leading developer of new perennials. [Terra Nova don’t do retail, ever, so please don’t ask.]

Terra Nova started by identifying a few existing foliage begonias and bringing them to a wider audience. The first was ‘Bentichoba’, a hybrid from Japan originally introduced in 1973, with silver and green leaves, tinted pink when young. This is actually turning out to be unexpectedly tough and is reckoned to be hardy outside in most of Britain (zone 8), dying down in the autumn like other perennials.

They began breeding their own and the interspecific hybrid ‘Metallic Mist’ was their first, with bold dark-veined silvery leaves. It’s thought to be even hardier than ‘Bentichoba’.

Then last year they launched a host of new foliage begonias which will be getting around North America this year and in Britain in a year or two. There are four series: the Garden Angel Series, Shade Angel Series, T Rex Series and the Cool Breeze Series.

The three in the Garden Angel Series (above, click to enlarge) are said to be hardy down to zone 7 (-18C/0F) and look as if they’re derived from ‘Bentichoba’. They’re big, making plants 2ft/60cm high and wide with large maple-like leaves in various combinations of silver, green tones, pink and purple. So, they should make dramatic hardy perennials in many areas.

The first in the Shade Angel Series, ‘Aurora’, is described as having “iridescent foliage in aquamarine, lavender, raspberry pink and cream overlaid with mother-of-pearl”. It’s quite something and would be excellent as a container specimen. Their T Rex series includes three more compact varieties in vivid colors and patterns that are again designed for summer containers outside.
Begonia Cool Breeze Series. Images ©TerraNova Nurseries
Finally, there’s the Cool Breeze Series (above, click to enlarge) in four foliage colors, including the silver leaved ‘Cool Breeze Rouge’ that develops pink tints in summer a little like a Caladium. These are for summer containers and will keep going well into autumn, not being damaged till the temperature is down to 38F/3C.

But I must also mention a seed-raised foliage begonia for summer containers that’s nothing to do with Begonia 'Gryphon' Image ©ProvenWinners.comTerra Nova.

Launched in 2011, ‘Gryphon’ (right, click to enlarge) makes a plant about 16in/40cm high and wide covered in large, jagged, dark glossy green leaves patterned in silver. Superb.

All these begonias should be available this season in North America. ‘Bentichoba’, ‘Metallic Mist’ and ‘Gryphon’ are already available in Britain, these startling newcomers from TerraNova should follow soon.

For more detail on all Terra Nova’s begonias, past and present, take a look at the begonia page on their website.


British sweet peas for American gardeners

More Scent': probably the best scented sweet pea of all. Image © Keith Hammett
A month or two back I discussed American varieties of tomatoes that British gardeners can order from across the Atlantic. Time now to return the favor, and point out the British sweet pea specialists who will send sweet pea seed across to gardeners in North America. Many will only send to Europe.

But first, it’s only fair to point out that there are two US-based sweet pea specialists. Sweet Pea Gardens in Maine, who I visited when working on my book on sweet peas, have a good range. Enchanting Sweet Peas in California also specialize in sweet peas. Also, Renee’s Garden in California has listed a good range for many years, along with seed many other fine flowers.

So, I’ve checked all the British mail order sweet pea suppliers and these five specialists will send seed to North America and also have easy online ordering.

Eagle Sweet Peas
Carefully chosen Spencer varieties for the gardener and exhibitor, including a steady flow of varieties raised by at the nursery.

English Sweet Peas
One of the largest wholesale suppliers of sweet pea seed to retailers, they also have their own online retail site listing a large range of old-fashioned, modern Spencers and dwarf types.

Kings Seeds
Founded in 1888, they list a fine range of varieties although the website is a little clunky and old-fashioned.

Matthewman’s Sweet Peas 'Clementine Kiss': a uniquely orange sweet pea developed by Dave Matthewman. Image © Matthewman's Sweet Peas
Thirteen consecutive Gold Medals at the Chelsea Flower Show, focusing on high quality Spencer sweet peas for the garden and showbench – including some excellent varieties that Dave Matthewman has raised himself such as 'Clementine Kiss' (right, click to enlarge).

Owl’s Acre Sweet Peas
I discussed Owl’s Acre in an earlier post and, in particular, their series of dwarf varieties for container. They also list a wide range of old-fashioned types, modern Spencer types and winter-flowering varieties.

A number of other suppliers are worth considering, but do not have online ordering; they need you to download and print an order form and send it in by mail.

Kerton Sweet Peas
Carefully chosen Spencer varieties for the gardener and exhibitor, including varieties raised by at the nursery.

'Deborah Devonshire': a lovely picotee sweet pea from Myers Sweet Peas. Image © Myers Sweet PeasMyers Sweet Peas
Carefully selected Spencer varieties for the gardener and exhibitor, including varieties raised by at the nursery including 'Deborah Devonshire' (left, click to enlarge), and some old-fashioned types.

Roger Parsons Sweet Peas
Large range of all kinds from the holder of Britain’s Plant Heritage National Collection of Sweet Peas (and other Lathyrus species)

Somerset Sweet Peas
Carefully chosen Spencer varieties for the gardener and exhibitor, including a fine selection of exceptional varieties developed by Keith Hammett including 'More Scent' (top, click to enlarge).

So many superb sweet peas, and some excellent, dependable British suppliers. And of course British gardeners can enjoy them too.


Transatlantic flower awards

Dianthus barbatus (Sweet William) ‘Sweet Black Cherry’, Petunia ‘Cascadia™ Rim Magenta’, Lobelia ‘Waterfall Blue Ice’. Images ©Ball Colegrave
There’s been a flurry of announcements of awards from both sides of the Atlantic, awards that result from the voting of real gardeners looking at real plants growing in borders and containers rather awards given by committees sitting round a table. So let’s run through some of the awards for summer flowers, I’ll take a look at this year’s tomato taste tests another time.

BallColegrave Visitor’s Favourite (Blue Flag) Award

Chosen by visitors to the summer trials and displays at Ball Colegrave in Oxfordshire, the UK outpost of the Ball Horticultural Company). neither sell retail, you make your choice by sticking a blue flag by your chosen plant, the flags are counted every day, and the numbers tallied. Last year’s results are here.

This year home gardeners picked a new Dianthus barbatus (Sweet William), ‘Sweet Black Cherry’, as their favourite, a first-year-flowering type for borders and cutting in a rich deep red. This was followed by the dramatic white-edged, Petunia ‘Cascadia™ Rim Magenta’ for hanging baskets and in third place Lobelia ‘Waterfall Blue Ice’, from cuttings not seed and very resilient, and a very colourful basket plant. (All above, click to enlarge).

For trade visitors (garden centers, commercial growers etc) Petunia ‘Cascadia™ Rim Magenta’ came top with the big and bushy Begonia F1 ‘Whopper™ Mixed’ second and the vivid orange-and-gold Zinnia ‘Zahara Sunburst’ third. Put all the voting figures together and Petunia ‘Cascadia™ Rim Magenta’ was the winner. Last year Calibrachoa ‘Cabaret™ Bright Red’ came out top overall – not even in the top twenty this year.

American Garden Award
Verbena ‘Lanai® Candy Cane', Zinnia ‘Zahara™ Cherry', Impatiens 'SunPatiens® Compact Electric Orange' Images ©American Garden Award

Across the Atlantic, visitors to thirty one public gardens across the country voted for the American Garden Award – which, in spite of its name, is given to plants. All the top flower breeders around the world pick just four of their new plants to enter – and the visitors vote.

The winner for 2013 was Verbena ‘Lanai® Candy Cane' with its colourful striped florets in long lasting heads. This was followed by Zinnia ‘Zahara™ Cherry', another in the very adaptable Zahara Series but in rich cherry red  and third came Impatiens 'SunPatiens® Compact Electric Orange'. This is a very vivid orange colour, it takes the sun well and of course is tolerant of the mildew which has wiped out do many other impatiens. (All above, click to enlarge).

People's Choice Begonia Award
Begonia 'Peardrops', Begonia 'Volumia Rose Bicolour', Begonia 'Nonstop Golden Orange' Images ©RHS

At the Royal Horticultural Society’s garden at Wisley, just south of London, more than 2000 visitors voted to name their favourite begonia as part of the charity's People's Choice initiative. They were invited to vote for their favourite in three categories.

Amongst the Begonia Semperflorens Cultorum Group (fibrous-rooted begonias) planted in borders, the winner was ‘Volumia Rose Bicolour'. A more vigorous plant than traditional Semperflorens cultivars, it has large white and rose bicolour flowers that vary in colour intensity depending on the temperature.

Favourite Begonia x tuberhybrida (tuberous-rooted begonia) winner, planted in borders, was ‘Nonstop Golden Orange'. Introduced as long ago as 1971 and, as its name implies, it has an extended flowering period that runs from late spring to late autumn.

Finally the favourite begonia of any kind for containers or hanging baskets was ‘Peardrop', a lush rich salmon and golden orange hybrid bred by UK breeder Dennis Need. (All above, click to enlarge).