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

We intend to collect enough rainwater to make our half-acre garden self sufficient. Advice please. Margot Hamilton via email

Depending on the needs of your garden you’ll need anything from a 6,000 to a 12,000 litre collection system which is a lot of tank. The best advice is to bury the tanks. You then have to decide whether or not the mains is to be connected (for topping up) and whether you want to use the water inside the house for flushing loos etc. All this will dictate the size of your tank/s. Then there’s the question of how you will utilise the water. Will you have the tank collected to an automatic watering system and, if so, will you want leaky or porous pipe? If the former do you want it pressurised (to give an even feed throughout the system) or not? There are so many decisions you will have to make that it’s worth talking to several specialist companies. There are lots on the web (such as www.freerain.co.uk/rain%20king.html). I have seen a demonstration by Watermatic systems www.watermaticltd.co.uk and they look like the business but the main thing is to find the system best suited to you and your garden.

I want to have a new year’s party in my garden and want to add mist.Don Singleton via email

There are two types of misting machines. One works by pressurising the water from an existing pond or water source http://www.mistmakers.co.uk/ so that the mist floats above the pond. The other is a chemical system http://www.cheapdjgear.us/Fog_Machines_and_Fog_Juice_s/22.htm used by DJs. The websites here are not recommendations so much as examples. You’ll find lots more.

My eucomis have disintegrated into a heap. Should I bring them indoors or is it too late? Phil Berry via email

If they are planted into the ground I should leave them. If in pots they should come into a frost-proof shed. Keep them moist, never damp, and start watering again in earnest next May. They should be fine so long as their bulbs have not been frosted.

My husband almost succeeded in burning down the party boundary but says that any damage is offset by the huge amount of potash generated by his Guy Fawkes inferno. How should we apply it? Name and address withheld

Ideally, store it until next spring when you should apply it as a mulch around hard-working fruiting or flowering plants. Potash is highly water soluble and, if applied now while plants are dormant, most of the goodness will have washed away by next spring when most plants start gearing up.

I am bored with the rose arches and pyramids available and would like something to put in a mixed bed to show off a climber. Laura Linton via email

Make your own design and have it made a local blacksmith. Just remember the golden rule that rose arches and supports are never high enough. They must be 8 ft minimum and much more robust than the twiddly things you can buy off the shelf. There are some exceptions like this http://www.classic-garden-elements.com/index_rosenl.htm which is excellent in terms of construction and looks.

Nearly broke my back skidding on my stone terrace. How can I sort out almost invisible slime to prevent further near-death experiences? Jules Bartholemew via email

Pressure washing will do the trick and so will Green Slime Remover http://www.lawsonscleaning.co.uk/productinfo.php?pid=1252. In the old days I would have recommended scrubbing the area with Jeyes fluid but it is no longer legal to use this stuff for terraces and so I would not dream of suggesting it.

I bought a green roof which has died off in parts and grows grass (not part of the original stuff we bought in blocks which was sedum) in other parts. Karen Hogan via email

It is a living roof and will therefore grow plants appropriate to the surrounding conditions. If the sedum is dying it is worth discussing the problem with the company that sold you the roof.

I am about to cut back my neighbour’s tree. Its branches have been shading my bed. Is it correct that I must return the branches to him, i.e. chuck them over the fence? Name and address withheld

I have always believed this to be the case but now discover, thanks to my learned friend the barrister Desmond Kilcoyne www.42br.co.uk who writes for the Sunday Times. He tells me that, strictly speaking, the branches have to be offered to your neighbour but, if s/he does not want to take them, it is your responsibility to dispose of them.

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

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