A. Not an easy one. Stags Horn Sumarch will sucker at the drop of a hat, any attack on the parent plant will result in all roots near the surface throwing up suckers like there's no tomorrow as a survival response.

You can get rid of it by a combination of chemical and physical attack, though each will result in a plethora of suckers. If the suckers are in a lawn, you can mow them down when they are small (you may wish to do this for your neighbor as a gesture of goodwill) and keep on going. 

I'd dig up as much as you can of the roots from the parent plant, you then need to attack the new top growth of suckers with a glyphosate based systemic weedkiller (one that is taken up by the leaves and taken to all parts of the plants). More than one combination of physical and chemical attack will be necessary, but eventually you will conquer the thing.

There are a number of pesticide resistant strains these days. The best bet is to keep a careful eye on your tree and spray at the absolute first sign of infestation. The pesky little critters have a very high rate of reproduction and can soon reach high densities.

Malathion, or similar insecticides work but must be sprayed at 3 - 5 day intervals. The real secret to beating these as many other pests is to get them quickly and before they establish. In the summer I usually keep a small spray of insecticide permanently made up to blast these and other pests such as aphids with as soon as I see them.

You need to make sure that the spray actually reaches them all. I know it sounds obvious, but they hide under leaves and make fine webs over themselves that even fine spray drops don't always pass through.

There is a predatory mite that you can buy as a means of biological pest control that has very good results if used at the right time, and they can't get resistant to that!

If you dig them into your veg patch every year, I would expect it to reach a certain level of acidity and then not get any greater, as you add more leaf mould, so another lot will rot and the acidity of that bit will reduce.

The overall effect won't be great however. If you have lots of leaves every year, it would be a real waste of valuable organic material not to use them. What I would do is add some lime to the heap when you gather them up in the autumn. This will help the pH of the leaf mould and also help the microbes to break the leaves down, they operate best in slightly alkaline conditions.

The lime will also help your compost heap when the leaves are dug in as most vegetables prefer alkaline to acidic conditions.

Leaf mould takes longer to break down than ordinary compost, so don't dig last autumns leaves in until the next autumn, they usually need at least 12 months, longer if possible.

Q. We are having some trouble with a steep bank. We want to plant with ground covering plants but until they grow we need to suppress weeds, have you any suggestions?

A. The simple answer is to mulch between the weeds as far as possible with bark chippings or compost. This may be a problem on a steep bank however. "Landscaping fabric" a woven plastic material available from garden centres and horticultural suppliers is good if difficult to lay between plants in situ.

My own approach would be to get a small 1L hand sprayer (or a bigger sprayer if you have it, but on-off control is important) and go around spraying carefully and very close up with a systemic weedkiller such as "Tumbleweed", use a piece of board to hold your ground cover plants out of the way and be as careful as you possibly can. You don't need to spray the whole of the weed plant, but aim for the centre and as much leaf area as you can.

Q. Raking back the gravel in my front garden I discover Tarmac. Attacking the Tarmac with a pickaxe revealed about six inches of hardcore. The plan now is to go for a raised flower bed! How deep does a raised bed need to be? I plan to plant climbing roses, clematis, small conifers.

A. For planting shrubs you need a minimum of 18" to 2ft for a raised bed, the deeper the better really. However for a lower bed, you could dig out the tarmac and gravel beneath the shrub and replace it with soil before planting above the hole you have made.

You need a minimum of a 6" diameter "plug" through the tarmac/gravel into the soil below, the bigger the better, 12" would be good, 24" better. You have to bear in mind that dryness will be the main problem and drainage will be good (excellent in your case) down to ground level, once the plant roots get below this, they'll be more self-sufficient.

Q. I have a Garden 10 meters by 3 meters. The topsoil seems very thin, then there is clay for at least another 60 cm or so. Underneath this is a chalk/flint layer (so my next door neighbor tells me). When it rains, and for some time after the ground is waterlogged and I can't even step into the area without loosing my shoes! It is fairly depressing.

Unfortunately the only access to the garden is through the house and I have no outside drains in my garden (It is a terraced house). How can solve this problem??

One of my neighbors dug out all of the clay and replaced it with topsoil and put in drainage to the main drains (but they are at the end of the terrace with easy access and a back gate. The other dug a big hole (2' x 3' x 2') and filled it with pea shingle. I can't help thinking that the reason mine is so bad is because the sump hole is next to my fence! What can I do?

(I live in Burgess Hill, this is on the south downs and used to be well known for its pottery works! Hence the heavy clay soil)

A. Not an easy problem to solve. If you want to deal with it properly then you aught to call in a drainage expert who could assess the site at first hand and suggest a solution, probably involving pipes set beneath the soil leading to a soak away at the end of your garden.

If you want a cheaper answer however it's going to entail a lot of work. It's difficult to advise not seeing the garden directly. My first approach would be in penetrating the clay layer to the chalk and flints underneath, a soak away like your neighbors may help or a series of mini-soak aways. Dig a couple of holes about 12" in diameter (about 6 ft apart) down to the chalk layer and fill the hole with shingle apart from the top few inches where you can replace topsoil. See if this has an effect and then extend if it appears to work.

You'll end up with a lot of clay to dispose of down the tip, but there's no real alternative other than call in the professionals, do it a bit at a time and you'll get there.

It will also help to dig organic matter, and pea shingle into the soil in as large quantities as possible, ultimately however it is the removal of the clay that will help unless you want your garden to be elevated by a foot or so thanks to the added material.

Q. We are not very good/successful gardeners and to make matters worse we are on solid clay. Hence we have had an extensive area of patio and decking in excess of 80m2 just laid and have decided to have lots of varying sizes of pots around the patio area. However, it appears that we need to be careful in what we plant as we are prone to quite a bit of wind and frost. Could you please suggest plants to put into these pots, some pots are already purchased and quite large. I like the idea of small trees and shrubs. The garden is south facing and is largely in the sun for the majority of the day.

A. If you going to plant a lot of containers, you have to make sure that you're going to water them regularly. They are more effort than having plants in the ground as they can dry out much more quickly having a lesser root system. If you have a lot it may be worth you looking at installing an automatic watering system.

It might sound like I'm avoiding the question, but I'd recommend you buy a good container gardening book as there are literally hundreds of plants you could grow, a book should cost you the same or less than one plant and so will easily pay for itself.

These will be ok in the conditions you describe:

There are a good number of small, slow growing conifers,
Buxus sempervivens - box,
Hebes,
Lavender,
Herbs in summer at least,
Rhododendrons (make sure you buy ericaceous compost),
Roses

Q. We have 4 dogs but we also like to grow herbs etc. At the moment we have the herb collection in pots, either perched precariously on bricks to keep them above dog leg height, or on a bench. As our collection grows this is becoming less practical. Short of banishing the dogs from the garden, can you suggest a practical, economical and hopefully attractive way to keep a large herb collection safe from canine contamination?

A. The best bet I think would be to build a raised bed. You can do this easily by using railway sleepers, a low brick wall or thick marine ply held in place with stout stakes. About 18" high would probably be adequate, and the herbs will like the extra drainage provided by the raised bed. You would probably like the fact that you will need to water less than you do in pots as the soil volume is much bigger.

We have tried digging it up several times but the roots seem to go down forever and we can't seem to get rid of it, it seems very determined ! We want to patio the area but need to get rid of the weed first.

We have 2 cats so am not sure what we can use to get rid of this weed without causing them any harm.

A. Japanese knotweed was introduced initially as a garden ornamental, but is now rapidly running amok in some parts (like in your garden!).

If you try and dig it out, you will invariably leave several broken pieces in the soil that will re-grow. With such perennial weeds, the only way to go is chemical. First of all dig as much up as you possibly can and take it down the tip (i.e. not onto the compost heap), stand back and let it re-grow. It will grow, but weakened as much of the food reserves are now down the tip. When there is plenty of leaf apply a weedkiller such as glyphosphate, Murphy's "tumbleweed" or the like. Keep the cats out of the way while you do this, (anything gentle enough to be animal safe is also pretty plant safe). The weedkiller needs to left a couple of weeks at least to do its job right down to the roots (follow the instructions on the container, you don't need to keep the cats out of the way all this time).

I'd then have another go at digging and remove any remaining pieces. It depends on how bad your infestation is, you may be ok now, or you may need to leave it to grow and then weed kill again. Long winded and labourious, but it will work.

Alternatively, if you are determined not to use chemicals, cover the whole area with old carpet or thick plastic, pull it up every so often and pull/dig the growing weeds, put the carpet back. In this way the weed roots will constantly be supplying energy to make new growth, but not be allowed to replace it by ever having any leaves in the daylight. This will take at least a year, maybe more.

A. How long has it been filled with water? If barrels have been allowed to dry out they will initially leak like a sieve when filled until the wood swells and fits together tightly.

If this doesn't happen, then it is not an easy thing to correct. You will have to dry the barrel out first to apply any water proofing compound, this means that the wood will shrink, once wet again it will swell meaning that it will move and so possibly the sealant won't work any more.

If your barrel is almost totally in the ground however I think the easiest way would be to pull it out and then line the hole with plastic, almost any will do as long as it's reasonably strong, and then put the barrel back. It will still leak, but the water won't leak away and the problem should be fixed.

If this is not possible, then take the barrel out of the ground, dry it out and clean the leaking points thoroughly, the best bet for a sealant is probably a silicone sealant available from pond supplies shops. Like I say though, this is a bit hit and miss and you may need to resign yourself to the fact that your barrel will now make a better planter than pond.

A. It depends on the length of the barrier, your budget and also how high you want the barrier to be.

For noise suppression a fence works best, the noise bounces back off it. This can be planted in front or behind with a hedge to hide the fence and also help soak more noise up. The hedge will also help to reduce dust and pollution from the road.

You need a thick dense hedge to suppress noise and the two plants suggested are ideal, evergreen, dense and quick growing (though slower than a fence!). Of the two I'd go for laurel, it's less unruly than Lleylandii and looks better too (it also flowers in spring). You could use Lawson Cypress if you don't like laurel, it's not as quick as Lleylandii which has advantages and disadvantages.

Another trick you could try is to have a small water feature in your garden. It's surprising how a fairly quiet feature with running water can help to disguise background noise.

First of all dig out as much of the root as you can. If you can't easily pull the growing ivy from the hedge, cut it off just above ground level, once the leaves have gone brown, they will be easier to remove as they won't cling anywhere near as tightly.

Once you've dug out as much as you can and have cut the rest off, stand back and let the plant produce a rush of tender green growth. Then you get really nasty with it and paint the ivy leaves with a systemic weed killer that is taken up through the leaves and taken to the roots. Make sure you wear rubber gloves when you do this. It will take a couple of weeks depending on the temperature for this growth to die down - remove it and wait for the ivy to repeat its process when you then again repeat yours with the weedkiller.

If you keep on top of it you'll succeed. What you want to avoid is letting it grow too much again and start to regain its strength.

It sounds like this pair have got into the habit, leave it for a couple of weeks or so and then remove it, they should be trained by then and go elsewhere. Of course there's nothing to stop them trying later on or another pair from arriving, but it's not that likely if your pond is small.

If that doesn't work, then try the naive approach - "What will you be doing with the garden? How will we be able to arrange our furniture is the slope is so great?" If you get no joy from the sales representative, ask to speak to the area manager. Bear in mind that builders often cut corners on the garden especially if it's not mentioned, "don't ask don't get" is often the rule. Simple landscaping is of negligible cost compared to the house and they may well get a JCB to shove soil around to make it more sensible for you. This kind of approach is best before any kind of deposit is handed over and sale agreed.

If this still doesn't give you a result, then all is far from lost. Drainage and flooding - shouldn't be a problem as this certainly is the builders responsibility. Ask about it if you are concerned and keep a record of what was said, by whom and when.

The garden can be dealt with by terracing, large flat patio / deck area near the house then retaining wall/s further up the garden to give useful areas. These conditions are frequently easier to deal with than is immediately evident to the inexperienced eye, a landscaper (not necessarily a hugely expensive designer) should be able to come up with some quickish simple solutions.

In short, don't worry too much about flooding, don't be afraid to ask the builder to correct things that you aren't happy with and if all else fails it's probably easier to rectify than you imagine.

Syn: "Synonym" e.g. Tom, syn. Thomas, Bill, syn. William, Bob syn Robert. A name that is the same as another name for the same plant / species / variety etc. but not the accepted one.