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Devon gardens to visit, a rescue plan for star jasmine, problems with blueberries, by garden expert Helen Yemm

Stream in front of the house at Coleton Fishacre, Devon
Stream in front of the house at Coleton Fishacre, Devon Credit: The National Trust Photolibrary / Alamy

Every week, Telegraph gardening expert Helen Yemm gives tips and advice on all your gardening problems whether at home or on the allotment. If you have a question, see below for how to contact her.

 

JOIN HELEN YEMM ON A TOUR OF DEVON GARDENS

There are still a few spaces to be had on what promises to be a lovely Boxwood tour this coming Sept 16-19 – a time when, as summer fades into autumn, British gardens can be at their most beautiful and are still packed with late summer colour.

I will be hosting the tour, and we will be led once again by garden historian Sophie Piebenga. Our base will be the exquisitely comfortable Endsleigh Hotel (one of Olga Polizzi’s stylish recreations), with its atmospheric Humphry Repton-designed gardens that we will enjoy and explore, overlooking a tranquil stretch of the Tamar. Days spent visiting some of south Devon’s most beautiful and intriguing gardens together will be followed by evenings of superb food and I am sure, much animated garden-chat.

On the menu will be a collection of thought-provoking gardens to suit all tastes – from Alasdair Forbes’ challenging symbolic gardens at Plaz Metaxu and Keith Wiley’s ground-breaking and aptly-named Wildside to the gentler acreage of The Garden House (where Keith was, for 25 years, the head gardener), the arts and crafts-era garden at Coombe Trenchard Manor and the subtropical plantings of the wooded coastal coombe garden at Coleton Fishacre, once the home of the D’Oyly Carte family.

We will also have lunch at Dartington Hall, stroll through the gardens and see Dan Pearson’s plans for their development.

The tour costs £2,380 per person sharing, with a single supplement of £300 and includes all meals, accommodation, guided garden entries and coach from Tiverton Parkway station, where the tour starts and ends. I do hope you will be tempted to join us.

For further information and 
to book, please contact Boxwood Tours, Quality Garden Holidays (01341 241717; boxwoodtours.co.uk; email: [email protected] tours.co.uk).

JASMINE CRUNCH TIME?

My adored inherited evergreen star jasmine on a west-facing wall seems to have lost its way. I treated a worse-than-usual scale insect infestation with an early spring spray (using Ultimate Bug Killer as suggested by you, I think). This was followed by the usual reddening/dropping of old leaves, also worse than usual. Growth looks gaunt, flowers are smaller and fewer than usual. I have never dared prune it. Would cutting it back rescue it, or kill it?

Bridget Moffat – via email

Trachelospermum jasminoides Credit: Gary K Smith / Alamy 

Provided the roots have plenty of space and the plant is treated to a spring drench of Maxicrop Seaweed plus Sequestered Iron (because of the general poverty and alkalinity of soil at the base of walls), you can, and probably should, prune your star jasmine if you have never done so.

Crunch time for my own 10-year-old trachelospermum (T. jasminoides or smaller-leafed T. asiatica) that had simply been allowed to clamber, twine and flower its socks off, came in spring 2018, when I noticed it had started to cantilever away from its trellis, its gaunt-looking branches only leafy and flowering on their extremities. Reluctantly, in March, I cut it right back to bare wood, suspecting that I might have to do away with it.

But it came back. There were hardly any flowers on the fresh growth that clothed it by late summer that year, but this year it is transformed: healthy, pest-free, relatively compact, currently covered in flower buds. The future? I shall tidy up a few wavy surplus shoots as flowering finishes, and I shall keep control by pruning it lightly each spring. I hope this is encouraging.

IN A BLUEBERRY JAM

I have two potted blueberries. Both usually fruit well, but last year one had an enormous amount of berries which stayed tiny. The same has happened this year. If I remove some of the fruit will the others grow to proper size?

Jakki Antrobus, Cheshire

Blueberries Credit: Phil Darby / Getty

Blueberries in pots are vulnerable 
to drying out and heating up. Is 
 the problem plant in a smaller pot than the other?

Heat sounds like the problem last year and I am not sure how you fared in Cheshire, but in the early part of this year in the South East we had very little rain and from time to time, considerable unexpected heat. I expect that few of us realised our blueberries might need water, just as the fruit started to develop. I would not remove any fruit, as they may yet enlarge after so much rain.

Rehouse your blueberries in wooden tubs that don’t dry out and heat up so easily, giving them some fresh ericaceous compost. Feed them in spring, with a high potash fertiliser, and after fruiting, with a general fertiliser.