e-mail Jane Owen with your gardening questions: jane.owen1@timesonline.co.uk

We are in despair about slugs and snails which have systematically destroyed our allotment this year. We applied the anti-slug nematode in April and that made a difference for a month – now it’s worse than ever despite picking off hundreds of snails and putting them in the field outside the allotments and using some nature-friendly slug pellets on our 40 X 40 ft plot. Edwina Little, Northolt

You are not alone. They are endemic this year. One of my friends recently got so fed up with the fact that his wife was doing what you have been doing - depositing his snails about half a mile away - that he decided to prove that this is a useless activity. He collected a bucket full and painted all the shells white. Guess what? Within a couple of days THE SNAILS WERE BACK. If you want to get rid of these infernal pests you must destroy them. You can do this by feeding the snails on porridge, boiling them and then adding some garlic butter (so delicious) or you can pour salt over the lot. Or drown them. Nematodes (minute, parasitic slug-like creatures which kill slugs and snails and can be bought online from various sites such as www.Organiccatalog.com, www.greengardener.co.uk, www.nemasysinfo.com and www.agralan.co.uk) are a particularly efficient method of killing slugs and snails but they are only effective when the soil is warm and then only for six weeks. In six weeks you can grow an awful lot – and then re-apply the nematode.

We have recently lost our tomatoes to the dreaded blight and could not have expressed our grief better than Alice Miles on 11th August. Ours grew on a tiny outdoor plot and we should be delighted to receive any advice you can offer as to what we need to do before planting out next year. S P Moran

Home-grown tomatoes are lovely but I’d be inclined to give the soil a rest for a year or so and buy fresh tomatoes from a local market. Hardly the same but it will save further heartbreak. The fungus which causes the blight, phytophthera infestans, can live in the soil and so, if you must persist with tomatoes (or potatoes), plant them in a different area. As soon as the first tomato sets, spray the plants with a copper-based fungicide or mancozeb and keep spraying regularly. Also avoid water splash (which can carry the infection) by watering at the base of the plants.

Some years ago I had trouble with clematis that would grow two or three feet and then die back. After several years of frustration I discovered that the cause was the bird feeder mounted on the post that supported the plant; the pumpkin seeds that the birds scattered are poisonous to clematis. How can I find out what other seeds or plants are not tolerated by their neighbours? Peter Dunn

I’ve come across plants like yellow rattle and mistletoe which feed off host plants and trees like beach which make it impossible for all but a few plants, like bluebells, to live under their canopy. But I have never heard of seeds affecting a plant in the way you suggest. And so I turned to Kew gardens for a second opinion and spoke to Annette Dalton, one of the garden’s horticultural managers. She confirmed what I say above and added: ‘seeds are susceptible to various fungi, and pumpkin seeds intended for human consumption have been recalled in the U.S. in the past as they were found to have fungi which release substances toxic to humans (aflatoxins). This could account for a fungal infection perhaps, but it's a long- shot.’

She went on to suggest you double check that your plant has all the basics needed for good health: ‘Is it getting adequate sun on the stems? Are the roots shaded? Is it mulched annually with well-rotted garden compost/manure? Do the leaves exhibit signs of nutrient deficiency? (Most commonly in Clematis - iron; intravenous yellowing of all leaves, manganese; intravenous yellowing of older leaves)

'It may be suffering from Clematis wilt, which is hanging around from season to season, so perhaps cut it back (look up the type to ensure the right timing) and clear all detritus from around it. Early next season water it a few times with a Magnesium chloride solution (Epsom Salts).’

By this time of year my garden looks dull. No flowers – nothing - although it looks fantastic from spring to June. And I hate chrysanthemums and asters. Steve Baker, Dorking

I’m not keen on them either but there are plenty more plants which look great now. A lot of the sages are in flower now www.dysons-salvias.co.uk in colours ranging from red to white to purple to sapphire blue (my favourite) and most have aromatic leaves. Some roses are having a second flush now, certain hardy hibiscus and abutilons look good now and Echinacea, rudbeckia (if you can stand yellow/orange flowers – I can’t) and late flowering clematis www.britishclematis.org.uk are all strutting their stuff.

The leaves of our strawberries, planted last year, have gone yellow. Name and address withheld

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