Buyer beware! 8 garden red flags that everyone should watch out for

The search for the perfect home is challenging enough, with a leaking roof or rising damp coming top of the list of unpleasant discoveries after new homeowners have moved in. But those aren't the only problems new house buyers might face, as too few pay attention to what's in the garden before buying. So which red flags should you look out for and what should you do about them?

1. Invasive plants that could devalue your home

Invasive plants like running bamboo, Russian vine or Japanese knotweed can not only cause problems for you as an owner, but they can affect the value of the house if you decide to sell in the future.

Japanese knotweed is expensive to get rid of, and banks usually require proof of an eradication management plan before issuing a mortgage on a property. Anyone selling a house is legally obliged to declare if there is existing Japanese knotweed, so make sure you check the garden carefully when you look around, as it can often be missed.

Running bamboo can spread over a metre a year and can be extremely difficult to remove, so if you find bamboo growing in a potential new garden, check which type it is and look for runners or other signs that it is an invasive variety.

Russian vine is also known as 'mile-a-minute' because it grows so quickly. If it's growing in your garden it can become a nuisance for neighbours as it quickly breaches garden boundaries. However, this also means that Russian vine growing in neighbouring gardens could pose problems for you, and if your neighbours aren't keen to get rid of it, you could be lumbered with it. So check before you buy!

Himalayan balsam is typically found near water courses and train tracks, where it quickly spreads by wind-blown seed. It's easy to get rid of, but persistent. Keep an eye out for it if you live near a canal, river or train line, and pull it out as soon as you see it, ideally before it flowers and sets seed.

2. Who really owns your garden fence?

Privacy can be an issue in gardens. Is the garden overlooked because of low fences or surrounding buildings? If there are any issues, will they be easy to resolve? A low fence may be ok if your neighbours are friendly and interested in discussing replacing the fence together. Check whose land the fence belongs to – the ownership of the fence depends on the property deeds. You may be responsible for replacing it or maintaining the boundary. Check also that the boundaries match the deeds and that there are no existing disputes with the neighbours.

3. Why you should visit during rush hour

Don't just look at the garden from the house or the patio – spend some time in it over a couple of visits, and at different times of day. There may be noise if you're below a flight path or near a busy road or school. If it's near a road, you might not notice the noise if you're there in the middle of the day, so check again at busier times if you can.

4. Spotting drainage issues

Soggy areas in the lawn or moss growing on hard landscaping could indicate that the garden has drainage issues. Check that the hard landscaping is sloping away from the house. If it slopes toward the house, water can pool around the foundations.

5. Why that narrow side path really does matter

If you're planning any hard landscaping or garden transformation, look at how easy it is to get to the garden from the front. Some houses have narrow passageways which you won't be able to get heavy machinery through, while others have no access at all, so you'll have to take everything through the house. Whether or not this is a problem depends on what you plan to do to the garden and the type of garden it is. Is it difficult to wheel your brown bin from the front to the back? This might not seem important at the time, but it could be irritating when you're living there.

6. The neighbour's security light problem

Check whether there could be any issues with neighbours' garden lights or security lights shining into your garden. As well as being irritating for you as a resident, light pollution has a negative impact on wildlife, including moths, bats and birds such as blackbirds and robins.

7. The toxic plants hiding in plain sight

If you have children or pets, have a look to see whether there are any plants that may cause harm. While many common garden plants – such as foxgloves and daffodils – are poisonous to eat, they are very unlikely to be ingested. However, some plants – including giant hogweed and plants in the spurge (euphorbia) family – have toxic sap that can cause severe skin irritation if you come into contact with it.

8. When trees become a structural threat

Trees that are planted too close to the house can cause structural damage. Their roots can get into pipes and also cause subsidence if they take too much water from the soil. There is also the risk that branches may fall onto the roof. If there are any trees that would need to be removed, this can be costly and should be taken into account when negotiating.