Annuals and seasonal plants

The coleus revival

'Rustic Orange' coleus, curly Kale, 'Pineapple Beauty' coleus and Pennisetum setaceum 'Rubrum'. Image ©GardenPhotos.comColeus are enjoying a spectacular - and well deserved - revival. And while Dibleys in the UK and Glasshouse Works in the USA have kept the old favorites available for many years, amazing new varieties of coleus in even more colors and color combinations, from seed and from cuttings, are now being introduced at an astonishing rate. There are even coleus for hanging baskets.

A fine new book on coleus appeared about five years ago (forty years after the previous one), three years ago almost a hundred were trialed outside by the Royal Horticultural Society and so coleus are now again getting the recognition they deserve. Those startling colors just keep tempting us and they look so good with some many other foliage plants and flowers.

In North America coleus (and of course their botanical name is Solenostemon) have remained popular as outdoor summer foliage plants for borders and containers. In Britain, they were relegated to conservatories and greenhouses because of the strange belief that they didn’t perform well outside. But I remember back in the 1980s – yes, yes, I know – that one of the star plants of the summer plantings along the Broad Walk at the Royal Botanic Gardens at Kew was coleus. Two old varieties in particular, ‘Sunset’ and 'Picturatus', were often used to edge the beds.

'Chocolate Mint' coleus. Image ©GardenPhotos.comAs I write Glasshouse Works in the US are listing 132 different coleus, Dibleys are listing twenty four coleus, fifty three coleus are promoted by the Proven Winners brand in the US but in the UK Proven Winners don’t feature any at all. But in just two years Terra Nova Nurseries (famous for the vast number of heucheras they’ve developed over the years) has introduced thirty seven new coleus in seven different series - in just two years! And their 2016 introductions have not yet been announced.

Terra Nova have spent eight years developing coleus and their introductions vary from tight and compact to big and bushy with two series (Color Clouds, below, and Color Carpet) intended for ground cover and hanging baskets. You can check out their series and all the individual coleus varieties at the Terra Nova home gardeners website.

At the moment, on both sides of the Atlantic, you’re probably most likely to see seed-raised varieties such as the monster-leaved Kong Series and ‘Chocolate Mint’ (above). But look out for these new series from Terra Nova and give them a try.

RHS Award of Garden Merit
These eleven coleus were awarded the RHS Award of Garden Merit, or had earlier awards reconfirmed, after being trialed the RHS Garden at Wisley and also on the Victoria Embankment in central London: ‘Black Prince’, ‘China Rose’, ‘Gay’s Delight’, Henna (‘Balcenna’), ‘Juliet Quartermain’, ‘Pineapple Beauty’, ‘Pink Chaos’, Redhead (‘Uf0646’), Trusty Rusty (‘Ufo6419’), Versa Crimson Gold (‘Pas733805’), ‘Winsome’.

Download the report on the RHS coleus trial.

Here are some more colorful examples of coleus from our image library at GardenPhotos.com


Coleus 'Color Clouds Honey Pie' Image ©Terra Nova Nurseries


Not yet winter in Pennsylvania

Geranium phaeum 'Samobor' seedling with startling fall leaf color. Image ©GardenPhotos.com
National Public Radio reported this week that lilacs were in bloom in Washington, DC. A friend near here in Pennsylvania reports picking salad leaves from the open garden just a few days ago while anther says her spring crocuses are in bloom. It’s been mild back in Britain too.

Here in our garden the mild season has ensured that some plants developing late fall color have lasted and lasted. One young seedling of Geranium phaeum ‘Samobor’ has produced some spectacular leaves (above, click to enlarge); the original plant and other seedlings are more of a blotchy yellow.

Hydrangea-quercifolia-Little-Honey-_J037665-700One of my favorite shrubs, Hydrangea Little Honey (‘Brihon’) (right, click to enlarge), a dwarf yellow-leaved form of the oak-leaved hydrangea, always turns burgundy red in the fall but often a couple of sharp frosts reduces the plant to bare stems. Not this year, the leaves have been wine red for weeks with a few just starting to develop fierier tones as they prepare to drop.

The other effect of these unseasonably mild weeks has been that after the first few, relatively gentle, frosts turned everything in the riverside meadows tawny brown – that’s how they stayed. The foxtail grass in the fields where the rudbeckias are such summer stars, I think this is Setaria viridis, has neither been crippled by frost nor battered by rain or snow and still stands out against the leafless escarpment. Lovely.

We’ve gentle frosts forecast for the weekend, with a high of 57F and a low of 39F forecast for Christmas Day. The snowdrops are in bud, but check out the Snowdrops In American Gardens Facebook group for news of plenty of snowdrops blooming merrily all over the country.

Oh, and a friend in Downeast Maine reports that the grass is growing and needs a trim. But I don’t care how long it gets here we’re not cutting the grass in December.

Foxtail grass, Setaria, still looking lovely on the Delaware River flood plain. Image ©GardenPhotos.com


Warmest ever fall in Britain

Viburnum tinus 'Lisarose' and 'Purpureum'. Image ©GardenPhotos.com
Just back in Pennsylvania, after a trip to England, and it’s been an unusually mild late fall and early winter on both sides of the water. Britain saw its warmest November day ever when the temperature reached 72.3F (22.4C) in mid Wales - “Remarkably mild for the time of year,” said the BBC radio weather man - and here in PA a friend told me last night that he’d just been out harvesting mesclun and baby greens from the open garden. Not bad.

Back in Britain the thing that especially struck me was the amazingly prolific flowering on Viburnum tinus, laurustinus as it’s sometimes called. Front gardens were full of their billowing flowers last week.

This is one of my favorite shrubs, with neat evergreen foliage, pink buds, clusters of white flowers and blue-black berries. The only problem, for American gardeners anyway, is that it’s not as hardy as we’d like. At USDA Zone 8 (perhaps 7) it’s fine in our English garden but wouldn’t survive even a relatively mild winter here in PA.

In his classic monograph on viburnums (still available on UK amazon and on US amazon), Michael Dirr describes twenty forms although almost twenty years later the RHS Plant Finder lists over thirty. My favorite variety is ‘Gwenllian’ with pink buds, blushed white flowers and reliably prolific berries that often last so long that they sit next to the following year’s flowers. But ‘Lisarose’ (inset left, above), with almost scarlet buds, Linaria 'Fairy Bouquet'. Image ©GardenPhotos.comcertainly looks tempting and the pure white flowers of ‘Purpureum’ (inset right, above), with their white buds have a very clean look and in spring there’s purple-flushed new growth.

The other thing about the mild autumn in England has been now long the annuals have been flowering. In some parts of the London suburbs, the roundabouts and roadsides were planted not with geraniums and petunias and marigolds for the summer, but with direct sown hardy annuals such as Linaria ‘Fairy Bouquet’ (left) in mixtures with Cosmidium ‘Brunette’ and the blue bracts of Salvia viridis. They were still attracting attention when I left a few days ago.

Next time: What’s striking about the late fall and early winter back here in PA.


Anniversary pansies span the years and the river

160 baskets of Viola 'Waterfall' on a bridge in Suffolk. Images © Thompson & Morgan

Now here’s a way to celebrate!

British seed and plant company Thompson & Morgan celebrates its 160th anniversary this year and to mark the occasion they’ve done something rather amazing. They’ve hung 320 hanging baskets from a bridge over the river near their headquarters in Suffolk, 160 on each side (click the picture to enlarge). And they’re all planted with T&M’s brand new, own-bred, fragrant, trailing viola mixture – ‘Waterfall’ (Brits will be able to order it in May).

First, they hired specialist highway contractors to fix the 320 heavy-duty hanging brackets in place, 8m (26ft) apart along the 1287m (4200ft) bridge, and then the baskets were hung. The teams worked from 12-4am over the last three nights. of March in liaison with local authorities. to cause minimal disruption to traffic. All be revealed today, 1 April.

A total of 5,760 violas have been planted in 3,200 liters (845 US gallons) of T&M’s own Incredicompost (yes, that’s what it’s called!) with 9.6kg (21 ponds) of their Incredibloom plant food added to keep them going till 1 June when they’ll be removed.

Of course, once they’re all in place, watering is the big challenge. But they’ve installed an automatic desalinating system that draws water from the brackish River Orwell below the bridge and doses the baskets with 2200 liters (580 US gallons) of water every day.

Well, I think this is pretty amazing. And I especially like the fact that they’re watered with desalinated water from the river below.

T&M say that “depending on public support” they’ll replace them all with summer flowers in June. So why not check in with Thompson & Morgan on the T&M Facebook page or follow T&M on Twitter and tell them what a great idea it is?


Developments in sweet peas

Lathyrus belinensis, discovered in Turkey in 1987A couple of interesting sweet pea developments to tell you about.

First of all, the hybrid made by Keith Hammett between the familiar sweet pea, Lathyrus odoratus, and L. belinensis (click to enlarge), discovered in Turkey in 1987, has been formally named by RHS botanist Dawn Edwards – Lathyrus x hammettii.

Keith worked for many years using L. belinensis with its yellow and orange flowers, to create a yellow flowered sweet pea – he started by crossing it with ‘Mrs Collier’ - and that work continues. But along the way it has, rather surprisingly, led to the development of some impressive reverse bicolours, sweet peas with the standard paler than the dark wings; ‘Erewhon’, which I discussed here a couple of years ago, is perhaps the best example so far. A full account of these hybrid and their origins was recently published in the Royal Horticultural Society magazine The Plantsman.

The other, perhaps even more startling development, relates to sweet peas as cut flowers. As you can see Long stemmed sweet peas from Japandfrom the picture (click to enlarge), a Japanese grower has managed to create sweet peas with extraordinarily long stems. I’ve yet to find out quite how they did it – not being fluent in Japanese is, of course, an impediment. But whether it’s new breeding or new growing techniques it would be interesting to know quite how they did it.


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