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October 2008
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December 2008

November 2008

Leaning towards removal

A friend in England emailed yesterday to ask what to do about her evergreen ceanothus that was blown over in recent storms. She described it as “very top heavy, like a robin” – you get the picture: a big round ball held up by two spindly legs. Plenty of top growth to catch the wind.At 1/8m/6ft height and 1.2m/4ft across at the top it doesn’t sound the most elegant shrub in the garden.

I’d be inclined to dig it out and plant something else – even another ceanothus. She could hammer in a fat stake, heave the plant into a vertical position and tie it up tight – but I can’t say it will be elegant and having torn out all those roots when it toppled, it may well die anyway.

Leaningbirchtrees700 Here in Pennsylvania we have a similar problem, though on a larger scale. Last month’s unseasonable snowstorm was one too many for our lovely 30ft multistem birch tree. It’s now leaning over the house at an angle of almost 45 degrees, with all the roots on one side pulling out of the soil. The next ice storm will have it crashing on to the roof.

The first picture shows the angle of the trunks as they are today (click on the picture to enlarge it). The second shows what one of last winter’s ice storms did to the poor tree, bending the trunk so the topmost branches touched the ground - just missing the roof. I posted about it back in February.Archingbirch500

The weight of last month’s frozen snow has pulled the roots free of the soggy soil so now the tree has so much less support – at least back in February the frozen ground kept the roots locked in place.

So, sadly, I’d better go get the chainsaw sharpened again

Christmas roses - long before Christmas

HelleborusNigerJoshua600 Well, I can’t match my friend Russ Graham over in Oregon who tells me he’s had a Christmas rose flowering at Halloween for the last three years – that’s amazing. But about ten days ago, I went out in the rain here in Pennsylvania and found the earliest Christmas rose we’ve had in flower here.

The plant flowering here (first picture) is Helleborus niger ‘Joshua’, bred in Germany by Josef Heuger who’s raised a number of good hellebores in recent years. I posted about it in December 2006.

‘Joshua’ was bred as an early bloomer and, although there are only a few flowers on the plant, it’s a treat to see its pristine white flowers when almost everything else is fading away. Over in NJ, where it’s slightly warmer, another variety from Josef Heuger, ‘Josef Lemper’ (second picture), is in bloom on plants set out only in June.HelleborusnigerJosephL500

Both these varieties, along with (more surprisingly) H. x ericsmithii ‘Silvermoon’ and H. x nigercors ‘Green Corsican’ have come through the winter here in PA and also in the chillier Ithaca, NY. These too are from Josef Heuger.

Russ Graham’s plant (third picture) is a selection from an early flowering strain developed by Ellen Hornig at Seneca Hill Perennials who had her stock from a friend. However, the problem with these plants for Ellen is that they flower in the fall or early winter – so when the seed is developing the weather at her nursery in Seneca, NY is especially hostile. Only in the spring, she tells me, if plants bloom again, does she get seed. The Heuger varieties are propagated by tissue culture.

HelleborusnigerHalloweenRG500 Russ has been on the trail of a genuine reliably Christmas flowering form of the Christmas rose for some time and this certainly seems to be the answer. Will it bllom so early in colder areas? I like the faint pink blush to its buds, too.

In the US, look out for ‘Joshua’ and ‘Josef Lemper’ in retail nurseries. In the UK, a few nurseries stock one or the other of these varieties – check the RHS PlantFinder for details. You can find out more on Josef Heuger’s hellebores here.

Another fiery fall invader

Euonymusalatus600 For much of the season, Euonymus alatus (winged euonymus/burning bush), is unnoticeable along the roadside. It just doesn’t stand out from all the other roadside shrubs along the Pennsylvania, New York and New Jersey byways. But come October, it suddenly reveals itself - the distinctive pink tinge to its red fall color catching the eye and marking it out from its neighbours.

Like the Japanese barberry I discussed last time, its dramatic fall color also outlasts that of most native trees and shrubs. It produces a great mass of seed, much loved by birds, yet under our two plants, set by our predecessor here, sheets of seedlings appear. Unlike the Japanese barberry seedlings, however, the deer eat them. The deer also reach up and eat the branches. See the guilty party in the second picture.

EuonymusalatusDeer600 Seedlings have often appeared in the woods nearby and in this rare case the deer do us a favor by eating them – after thirty years there are no established offspring of the two original plants.

The University of Connecticut, who are working to create a sterile Japanese barberry, are also using genetic engineering techniques to develop a sterile Euonymus alatus. But will gardeners want to plant a genetically engineered burning bush, or a genetically engineered Japanese barberry- even if it is sterile?

Safe to plant Japanese barberries?

Berberisthunbergii600-1711 Sometimes it’s obvious why people plant invasives in their gardens. This Japanese barberry, Berberis thunbergii, has been providing an unusually brilliant splash of fall color for many weeks now and it's still looking when most of the rest of the fall color is gone..

Genuinely fiery, the plants scattered about the woods seem to vary in precisely the tone of yellow, orange, gold or scarlet they adopt and there are strings of scarlet berries too. The Japanese barberry is delightful, but it’s a menace.

However. I have to say that without the deer eating just about everything else in the woods but ignoring the Japanese barberry it’s as much the fault of the deer as that of the naturally self seeding barberry.

Because the barberry is such an important garden plant, efforts are under way to develop sterile forms which won’t spread from our gardens into the woods. Researchers at the University of Connecticut, in a limited study, found that seed production of f. atropurpurea was 32 times that of ‘Aurea’ and ‘Crimson Pygmy’ – partly, presumably, because the plants grew much larger. And all those tested produced at least some plain green-leaved seedlings. There’s more here.

Interestingly, the gardener looking after the Royal Horticultural Society's current trial of 70 different Berberis thunbergii reports hardly a single self sown seedling has appeared since the trial began in 2005 - and she doesn't use any weedkiller on the trial.

Now, the University of Connecticut’s researchers are working on developing sterile triploid barberries (with three instead of the usual two sets of chromosomes) and also using genetic engineering to add a gene for sterility into barberries. There’s more here.

Of those around at the moment, B. thunbergii ‘Sunsation’ is said to be completely sterile, and B. x mentorensis (a cross between B. thunbergii and B. julianae) is said to be almost completely sterile. The work at the University of Connecticut looks more promising.