September 12, 2011

Designing with Phyllostachys nigra

As a garden designer I was always trained to have strong responses to the things I liked or disliked. “Nice” was a banned word so when I decided to post on Phyllostachys nigra, I considered entitling it “On the glories and vicissitudes of….” – a bit convoluted perhaps but quite appropriate as this is a plant which elicits a strong response for many reasons.

It was my latest design project which finally convinced me that this really was a glorious plant. Here is a picture, taken sadly on a rather dull day but nevertheless showing what I was trying to achieve:

Umbrella pruned Phyllostachys nigra

Mature specimens make a fantastic screening plant also giving a strong architectural effect, whilst taking up a relatively small amount of space in a very tight urban courtyard area.

Many bamboos are strong architectural plants but it is perhaps the distinctive ebony colouration to the culms of Phyllostachys nigra which make this plant a favourite with designers and clients alike. Evidently there is something about the black canes and strong green foliage that fires our imagination and it would be fair to say that black bamboo has been often specified, particularly in the urban courtyard where space comes at such a premium. What we should remember is that the black canes grow green and require plenty of sun to mature into that gorgeous deep ebony.

Another particular characteristic of Phyllostachys nigra is the delicate leaf form.

culm and leaf of black bambooCompared to many large bamboos the leaf is very small and one of the wonderful things about this is that you can have a dense canopy which will still allow the passage of light. Rather like the screening offered by small leafed trees such as Betula pendula. So no need to worry about being engulfed in gloom in your garden paradise. The drawback on the leaf is that its delicacy makes it more prone to wind damage so it should always be placed in a relatively sheltered area. A much better all-weather bamboo would be Phyllostachys bissetii.

So, what else is bad about Phyllostachys nigra? You couldn’t criticise it for being slow growing but you might wish to choose a form of bamboo which performs to its full potential within a shorter space of time. It is slow which means that you very often see rather weedy specimens with a wealth of rather spindly canes. In fact, how often do you see what you could honestly describe as a glorious example of Phyllostachys nigra? The other consequence of their slowness is that mature specimens are more costly to purchase.

Phyllostachys nigra is described by most people as a clump forming bamboo. However, there are those who might well beg to differ. It wouldn’t be overstating the case to say that once it does get going, it is most thuggish in its advance. Unmanaged, it can become an extremely onerous task to remove this plant. So, if you wish to restrict its movement, make sure that a root barrier is used.

But let’s not dwell too much on the negative. Perhaps one of the most beautiful attributes of this plant is its gently arching habit. This is not a fastigiate or erect bamboo but one that is often gracefully pendulous. So give it a bit more room. Choose which culms to keep and accentuate the architectural form of this plant. A much better bamboo if you are looking for straight and erect, would be Semiarundinaria fastuosa or Japanese Temple Bamboo.

Which leads me to presentation. Thin, straggly stems should be removed in any case so that energy of growth is directed to where it is needed but you can prune bamboo into a parasol or umbrella form if you want something less hirsute or bushy. Best to remove branches while they are young as it is much easier then to get a smooth and “un-knuckled” culm, though you can remove at any stage. The result is delightful in its elegantly architectural stature.

Phyllostachys nigra in gravel mulch used as a screening plant in urban courtyard

Appropriately, I found this rather beautiful specimen at the entrance to Architectural Plants in Horsham:

Phyllostachys nigra umbrella pruned for screening

And maintenance? Well, there are those who would say that more often than not, bamboo looks rather tatty in this country because it is simply better suited to a warmer climate. Sure, many of the Wildernesse areas of Italian gardens feature groves or even forests of bamboo but I’ve seen terrific specimens in Wales too. Most bamboos like sun but most importantly, they love moisture. So if you ensure that your Phyllostacyhs nigra is well-irrigated during its growing season then you are likely to do well.