Helen Yemm: green cover for city gardens, shrubs with spots, agapanthus for a pot
City scramblers
I have aJasminum polyanthum growing against the sheltered south-east-facing return wall of my London terrace house, covering some ugly drainpipes. I love its spring scent, but it is too big and too “high-maintenance”, and after years of hacking to control it is now ugly at the bottom. Is there a more appropriate climber which might look good, cover my pipes and behave more reasonably?
Phillip Lightowlers, via email
Your email took me back to my own formative gardening years of limited light, limited space, London-terrace-house gardening, a lot of which had to do with hiding “unsightlies” and teetering on ladders. So, my ideas for a replacement for this jasmine, which is the one most often sold as an indoor plant but is just about hardy when grown against a sheltered house wall, come from personal experience.
The current favourite, slow-growing evergreen “jasmine” Trachelospermum jasminoides would do the job eventually, has scented flowers and is generally well-behaved. However, if you can sacrifice the scent*, I strongly recommend Solanum jasminoides ‘Album’ (also now known as Solanum laxum ‘Album’), a beautiful, vigorous, drainpipe scrambler, which uses its leafstalks (petioles) to grab hold of available support (see above). Two vertical wires are all it needs to get going and, once aloft, it will produce showers of starry yellow-centred unscented “potato” flowers for weeks, often months.
In London it is generally evergreen, but roughly one year in four a frosty wind will “get” its upper regions, turning them to black dishrags until you haul it down and lop it. It will set off again from the base in March, hitting the heights and flowering again before midsummer. Do not be tempted by Solanum crispum ‘Glasnevin’ which is not a true climber. * For summer scent, grow shrubby perennial stock (Matthiola incana) elsewhere on your plot.
Copy of Tip for late April: camellia essentials
Spotty shrubs
My arbutus (strawberry tree), much admired for many years, is now suffering. Recently some branches have black marks on leaves which have shrivelled. I have sawn off one dead branch, but now fear for the remainder of the shrub. Can you diagnose and prescribe a remedy?
Basil Hillman, via email
Shrubs don’t live forever, nor will they keep their looks without input. After careful perusal of your pictures, I reckon this ailing thing has suffered in the feeding/TLC department, which has left it weakened and susceptible to disease. The giveaway, I hate to say, was the messy leaf-litter and competing all-sorts around its base. (Pictures are so helpful, readers, but they tell me a lot about your gardening habits…). In this case the spotty leaves look to me like signs of a fungal disease of some sort – similar to the fungal spot that almost defoliates Photinia fraseri in early spring, I suspect. Leaf spots are hard to control using available fungicides, although you could try spraying with systemic Fungus Fighter Plus. Picking up all fallen leaves will help limit the numbers of spores wafting around, while treating your plant now and every spring with a general fertiliser and a drench, before covering the ground under its entire canopy with a mulch, will encourage new growth and help fortify it.
Agapanthus for the spotlight
I have a fairly informal garden with a square pond in the centre. I want to plant a small interesting shrub in a container on the paving by the pond. I like the umbrella shape of Acer palmatum dissectum, but suspect it would not do well in an exposed, sunny site. Can you suggest an alternative specimen plant?
Pat Bolland, via email
You’re right. With leaves that scorch easily, it is likely that a Japanese acer would not live long enough in a container to form a classic umbrella shape. They are woodlanders that, when young, only thrive under a higher deciduous tree canopy which offers protection from wind and sun.
Your picture helps me get a feel for your garden: The pot is glazed and attractive (a “statement” in its own right), the pond has a paved surround, and the surrounding garden is open and classically informal. What I feel would look great is a stately, clumpy, agapanthus. Agapanthus looks exotic and “difficult” but the hybrids are hardy and their seed heads remain beige and beautiful into late autumn.
A good-sized plant, or two or three smaller ones tucked in together, would probably flower a little this year but, given a weekly liquid feed, would come into its own after that.
