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August 2015

New research: Non-native plants just as good as natives for pollinators

Verbena bonariensis and Lobelia tupa, two valuable Southern Hemisphere pollinator plants from South America  on the RHS Plants For Bugs research plots.
There’s been a great deal of controversy about whether native plants are best for pollinating insects or whether non-native garden plants are just as valuable. On the whole, the debate has been informed by more opinion than science but, after a four year research project at their Wisley garden near London, the Royal Horticultural Society has the answer. This is the first ever designed field experiment to test whether the geographical origin (‘nativeness’) of garden plants affects the abundance and diversity of invertebrates (wildlife) they support.

“Until now the role native and non-native plants play in sustaining wildlife in gardens has been unclear and confusing,” say the lead researchers on the project Dr Andrew Salisbury and Helen Bostock. “Now, for the first time, gardeners can access robust, evidence-based information on the most effective planting strategy they can adopt if they wish to attract and support pollinators.”

Over on her Plants For Bugs blog, Helen Bostock summarizes the three main conclusions of the research (her emphasis in bold).

“1. The best strategy for gardeners wanting to support pollinating insects in gardens is to plant a mix of flowering plants from different countries and regions.

VerbenaBee“2. Emphasis should be given to plants native to the UK and the northern hemisphere, though exotic plants from the southern hemisphere can be used to extend the season (there are a greater proportion of exotic plants flowering later in the season compared to UK native and northern hemisphere plants) and provide nectar and pollen for some specific pollinators.

 (Left, Verbena bonariensis from South America)

“3. Regardless of plant origin (native or non-native), the more flowers a garden can offer throughout the year, the greater the number of bees, hoverflies and other pollinating insects it will attract and support.”

So there you have it, research at the RHS (part of the research area above, click to enlarge) the best way to encourage pollinating insects is to “plant a mix of flowering plants from different countries and regions” – and not to rely only on native species.

Supported by the Wildlife Gardening Forum, this is exactly the sort of research we need to demonstrate the Entomologist Andy Salisbury uses a Vortis suction sampler to collect insects in the Plants for Bugs experimental plots at Wisley proven realities of an issue which has been dominated by the trading of opinions such as “Native plants will attract more native pollinators” masquerading as facts.

Let’s hope the RHS team will soon be looking at the relative importance of native and non-native plants in providing food for those larvae of native insects which do not require specific native plant species on which to feed – for although the point is pretty much proved in Jennifer Owen’s Wildlife of a Garden, it would be good to have research on the same scale this newly published RHS research to make the point.

* You can read the full details of the RHS research online in the Journal of Applied Ecology.
* Take a look at the latest addition to the RHS guidance on Plants For Pollinators based on this research.
* Read the background to the research and how it was done.

New heuchera that's quietly different

Heuchera 'Berry Timeless' is a container in partial shade. Image © GardenPhotos.comIn the first waves of enthusiasm for heucheras, back in the 1930s and then the 1950s, it was the flowers that were key and in fact many varieties were developed specifically as commercial cut flowers.

More recently, of course, foliage has been the thing and an astonishing range of foliage colors and patterns has been developed although many have poor flowers which are best snipped away.

So, obviously, the next thing was to bring the two features together. ‘Rave On’ is pretty good in combining good foliage with good flowers, but flowering tails off as spring passes. But, so far, ‘Berry Timeless’ (left, click to enlarge) really does look the part - even if the name is a bit corny.

OK, this is its first season on trial here but it’s clear that its bright silver foliage with minty green veins makes a lovely low dense mound. The flowers open in pale pink and fade to richer tones and, unlike the flowers many heucheras, they don’t fall off. Even while the little green seed capsules are developing the dusky reddish pink flowers are still colorful.

Old and new flowers on Heuchera 'Berry Timeless'. Image © GardenPhotos.comIt’s now August and there’s plenty of old flowers, new flowers and buds still on the plants (right, click to enlarge). And there’s another thing about the flowers: the length of bare stem below the flowers is relatively short so the flowers sit just above the leaves without a long length of bare stem in between. That’s a feature that really improves the look of the plant.

Developed by Walters Gardens in Michigan rather than the heuchera hatchery that is Terra Nova Nurseries, where most new heucheras originate; look out for more from them in the future.

Heuchera ‘Berry Timeless' is available in Canada from Canning Perennials and in the USA from Garden Crossings. It’s not yet available in Britain, but should be soon.

Plant names with a groan

Nurseries and plant breeders plunder a huge range of sources when dreaming up names for their new plants. Gone are the days of ‘Purple Prince’ and ‘Snow Queen’, most of the names in that traditional style have already been used – and you can’t use the same name twice for the same kind of plant. So new names are in constant demand.

Pulmonaria 'Dark VaderOne of the most popular tricks is to adapt a familiar phrase, often by creating a groaning pun – which may, or may not, have some relation to the plant itself. Here are a few examples from books, music and films.

Pulmonaria ‘Dark Vader’
We all know Darth Vader from Star Wars - not a very nice person. Indeed he’s become a popular symbol of evil. So it seems odd to adapt his name and attach it to a plant in the hope, presumably, that it will help sales.

Pulmonaria ‘Dark Vader’ (left, click to enlarge) is a lungwort developed by Dan Heims at Terra Nova Nurseries in Oregon and is known, depending who you ask, for its silver spotted, dark green foliage or its flowers which open pink and then turn dark blue. Neither the foliage nor the flowers seem especially dark to me - and certainly bear no relation to the black of Darth Vader’s costume - although its many months of brightly spotted foliage and its prolific spring flowering make it a valuable shade garden perennial. It was introduced in 1999 although ‘Cotton Cool’, introduced the same year, is a better plant and much more popular. Most of the other pulmonarias Dan introduced that year are no longer grown.

Pulmonaria ‘Spotted Dick’ (Yes, really!) I’ll get to this another time but, in the meantime, if anyone has a picture of this variety please let me know!

Tomato ‘Sweetheart Of The Patio’
Sweetheart Of The Rodeo was sixth album by American rock band The Byrds, and their first to fully embrace country music. Released in 1968, to this day it remains an iconic country rock album. It’s simply wonderful.

‘Sweetheart Of The Patio’ is a semi-trailing patio tomato for containers developed by John Burrows at Pro-Veg seeds near Cambridge, England. It is known for its early fruit set, its prolific crop of 1in/2.5cm fruits and especially its resistance to late blight disease. It’s closely related to the All America Selections winner ‘Lizzano’ and has been popular in the US since its introduction a few years ago.

Chili Pepper ‘Born To Be Mild’
Born To Be Wild was a single released by the American rock band Steppenwolf in 1968. It was written by the splendidly named Mars Bonfire – who previously went by Dennis Edmonton and before that Dennis Eugene McCrohan. Obviously, if you want to be a rock ‘n’ roll star, Dennis Eugene McCrohan doesn’t really cut it. Mars Bonfire is much more like it, and a pretty good name for a hot chili pepper, actually.

Heuchera 'Grape Expectations', Begonia 'Truffle Cream', Alyssum 'Snow Princess'. Image ©GardenPhotos.comAnyway, Chili Pepper ‘Born To Be Mild’ is a slim, 3in/7.5cm long pepper with all the flavor of a jalapeno but none of the heat.

Heuchera ‘Grape Expectations’
Here, the name of the Charles Dickens classic has undergone a clumsy metamorphosis and been applied to a new heuchera with grape-colored foliage (right, in June, click to enlarge) and the failed expectation that it will retain that that rich coloring all summer. In fact, while grapey in spring and early summer and in fall, it turns silver in between.

Developed at Walters Gardens, MI and available retail next year, Walters have also developed the red-flowered ‘Berry Timeless’ so we can see where they’re going with naming their names. In the same style, there’s also Ilex verticillata Berry Heavy (‘Spravy’) and Berry Nice (‘Spriber’), selected by Dale Deppe at Spring Meadow Nurseries, MI.

As it happens, ‘Berry Timeless’ is proving to be an exceptional plant in its first year in the garden. More about that next time.