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

How can I stop cats using my small garden as a toilet? The smell is disgusting on the warm evenings we’ve started having which are the only times we use the garden. The Harveys, London

Victorian gardener Mrs Haweis, who wrote the catchily titled ‘Rus in Urbe or Flowers that Thrive in London Gardens & Smoky Towns’ had a running war with cats. She said that the beasts should be taxed because they possess ‘…..no homes no principles, no remorse.’ I’m rather fond of them although their lavatory habits are infuriating. I used to recommend water pistols, kept at various strategic places through the house and garden, to ‘shoot’ cats as they appear. They hate water and will get the message. This is not an option if you’re only at home in the evenings. Instead, try a new type of ultrasonic deterrent which emits a cat-scaring sound only when the animal is around – this a crucial difference to conventional ultrasonic devices which are simply ‘on’ or ‘off’ although some can vary their pitch. The new type means that cats never get used to the sound and will stay out of your garden permanently. However, beware of rip-off merchants. It looks as if the device works best when it is plugged into the mains rather than working for batteries – and the cost, including delivery, ranges from £25 to nearly £100! Primrose, London sells it for about £25 www.primrose-london.co.uk which seems reasonable but let me know if you find a cheaper supplier.

Another option, if you or your partner wants to be macho about the cat problem, is to buy a Mega Sonic Scatter Cat Repeller Gun with laser sights www.martleyelectronics.co.uk which means pointing and triggering an ultra-sonic gun at the culprits.

Finally, to return to the redoubtable cat-hater, Mrs Haweis, I sometimes feel she was the world’s first makeover gardener long before the likes of Diarmuid, Charlie and Alan. This is her recipe for an instant garden in 1880s London: ‘..a shillings worth of seeds, with a barrowful of gravel, will make a decent scene of a dirty little wilderness. Tile edging is cheap. A small fountain with a pipe laid on a top cistern costs little. Rockeries are easily got up. Turf itself can be persuaded.’

I was searching house foundation problems and flowering cherry tress when your advice on the Timesonline page came up. There is a spring flowering cherry in the garden next door to us. It is over 25 foot high and is some 8 foot from the wall of our house. The roots have already caused the paving on our side path to lift. I am concerned about how it might affect the foundations of our house. I would be grateful if you could say if it is likely to cause damage to the foundations. Bill Buckley, Harrogate

This is a tricky question for a number of reasons and I think that, if you are certain that the paving was lifted by the neighbouring tree’s roots, you need to discuss the problem with the tree’s owner and bring in an expert to find out if any damage has been or will be done to your house. It may be worth contacting your local council’s tree expert – they can sometimes be helpful in matters like this. One thing to bear in mind is that tree roots exist to find moisture as well as providing anchors. Therefore, unless your house foundations are damp or there are broken drains nearby, the roots may be avoiding the foundations. On the other hand they may not and so you need to get an expert on site to give highly specific advice.

Is it true that compost run-off ‘burns’ plants? N. Wilkinson, Aylesbury

It can if it hasn’t been diluted. On the other hand it makes a fantastic feed when it’s diluted at a rate of about 1:10. I have been feeding my cucumbers, amongst other plants, with my compost ‘tea’ and they are threatening to take over the house.

Can Eucomis survive in borders? Anna Valtorta, Venice

Yes, so long as they have a sheltered, sunny spot and fast-draining fertile soil. Having said that they like plenty of water when in flower. In Venice you’re unlikely to get the really low temperatures that can kill Eucomis in winter but, if in doubt, add extra mulch in autumn.

The grasses in my garden have been caned by the rain. Betty Holbarrow, Berks

I’m not surprised given the exceptional rainfall we’ve had. Stipas and Deschampsia seem to be less robust in heavy rain but compact plants like Corynephorus canescens – and tough old Miscanthus should be OK. All the same I have little sympathy with grass lovers. Why not plant beautiful flowers or lush foliage plants instead of grim old grass which only looks good for a few weeks a year and then only in certain lights?

Are there any climbing roses which thrive in shade? Name and address withheld

On the whole roses like the sun but a few will tolerate shade. My favourite of these is the deep red, deeply scented Souvenir de Docteur Jamin which was looking particularly good at David Austin’s stand this Chelsea. New Dawn, the wonderfully scented pink rose Zephirine Drouhin, Sander’s White, Gloire de Dijon and Mme Alfred Carriere are also good roses that will grow in shade

Can spiders bite? Jon Barnard, Liverpool

Yes – and if you are affected you may need to get help - fast. For more general information about spiders that bite in the UK the Natural History Museum’s site is helpful www.nhm.ac.uk. Even the common garden spider Araneus diadematus bites.

We’re off on holiday for a week at the end of August. When we returned from holiday during the hot spell earlier this year our garden pots were dead. Our neighbour swore he’d watered them! Name and address withheld

Non-gardeners never water enough (I assume your neighbour is not a gardener) and so you have to educate them. Have him round for a drink and show him how much water you have to give to pots etc and tell him how many times it needs to be done during hot weather. To be on the safe side, gather all your pots into one shady place and add a water-retaining mulch. The alternative is a computer-controlled irrigation system – but that costs serious time and money www.garden4less.co.uk

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

Explore Gardens

• Hampton Court Palace Flower Show

• Chelsea Flower Show

Times recommends

• Here comes the glass sun – garden honours Beatle
• Gardening tips: 10 things to know about Horny Goat Weed or Epimedium
• Diarmuid Gavin shares tips on how make your garden fun and funky