The dictionary describes a weed as either; "a valueless plant growing wild, especially one that grows on cultivated ground to the exclusion or injury of the desired crop." or "any undesirable or troublesome plant, especially one that grows profusely where it is not wanted.". Sound familiar? This article will help you identify what type you may have encountered in your garden and, more importantly, the best way of killing weeds.

Killing weeds is not as simple as it sounds. You could spend hours in the garden digging, hoeing, picking seedlings, following roots and lifting paving slabs to try and get to the bottom of the problem but there is only one solution that is almost always guaranteed to work when killing weeds, and that is using a weed killer. Before you choose which type of weed killer you need, it is best to identify the type that you have in your garden so you know when to tackle killing weeds.

There are three main categories of weed:

Annual – these weeds only survive for one season and then spread their seed in the autumn ready to germinate for the next season. By killing weeds of this type before they seed, you will prevent them coming back the following year. Examples of Annual weeds: Chickweed, Purple dead nettle, Groundsel, Annual nettle, Fat hen, Opium poppy, Hairy bittercress, Annual meadow grass, Speedwell, Yellow oxalis.

Biennial – this type of weed take time to mature and, after two seasons, will be old enough to produce seed and will then die leaving the seeds to grow. Killing weeds of the biennial variety is best done in the first year of growing when the plant is low to the ground. Examples of biennial weeds: Caper spurge, Evening-primrose, Giant hogweed, Goat's-beard, Hogweed, Spear thistle.

Perennial – these weeds form a root system and can live for many seasons if not tackled early. It is more difficult killing weeds of this type as they have different ways of ensuring they survive and reproduce. They can produce seeds like annual and biennial weeds which can be spread over wide areas by the wind and also by animals that may eat them, and also their roots can reproduce stems even if the original plant above the ground has been destroyed by grazing animals or even fire. These roots can lie in wait underground until the start of the new season. Examples of Perennial weeds: Bramble, Sorrel, Bindweed, Mugwort, Clover, Creeping buttercup, Ground Elder, Yarrow, Dandelion, Creeping thistle.

So now you know the three types you need to know when best to go about killing weeds. As mentioned earlier, weed killer is by far and away the best and most effective way of killing weeds and their roots.

There are two types of weed killer on the market – selective and non-selective. These both have different purposes and applications. If you are killing weeds over a large area then non-selective would be the best choice as it kills all plant life it comes into contact with. Selective weed killers are designed to only target only one species when killing weeds and, as long as they are used correctly, should not cause damage to plant life in the surrounding area and are mainly used in the agriculture industry where weeds may have developed amongst crops so need to be targeted specifically without harming the produce.

Killing weeds of any of the three types listed above is best done by using a non-selective weed killer that not only attacks the foliage of the weed but also the roots. When tackling biennial weeds always try and kill them in the spring before they spread their seeds and cause further problems. If you have a problem with perennial weeds then tackle them in their first year of growth, again before they can spread their seeds which could develop the following season. Perennial weeds are a little harder to attack – as they are not always above ground, non-selective weed killer has to be applied to foliage when killing weeds so you will have to look out for when they appear above ground and target them then.