There are many different types of fertiliser and weedkiller that can be applied to lawns, but why would you want to do so? The general answer is to improve the lawn, which they can do in a number of ways.

Fertiliser, which may also be sold as lawn food or as some types of lawn greener, is used to provide extra nutrients to help the grass grow. Grass that hasn't been treated can deplete the nutrients that are in the soil and, if they aren't replaced, this can make it easier for hardier plants such as weeds and moss that are better suited to growing in soil with poor levels of nutrients to start invading the lawn.

Weedkiller, naturally, kills weeds, and some types are also designed to kill moss as well. Be aware that after a lawn has been treated with moss- and weedkiller it may look patchy after the moss and weeds have been killed off, as a lot of the "lawn" may have actually consisted of weeds. At this point grass seed may well need spreading on the patches that appear to establish new grass there before the weeds come back. This should probably be done at the beginning of the growing season so that the new grass has enough time to establish itself.

Be Sure to Read the Instructions

Before applying the fertiliser, or weedkiller or a combination, to your lawn, make sure you read the instructions, and read them properly. Most chemical supplements have various prohibitions about when they should, or should not, be applied, especially regarding pets and children, the treated areas, and those fertilisers combined with weedkillers, or weedkiller by themselves. Weedkillers are normally poisonous, so care needs to be taken with their use. Accidentally getting them into a fish pond will have potentially fatal effects on the fish for example.

Some supplements will require "watering in" before allowing children or pets on the lawn, although keeping them off is not the easiest thing to do. Often, you will need to water the lawn if it doesn't rain within a specified amount of time as stated on the container the supplement came in after it is applied. This is frequently true even with those that don't require children and pets to be kept off the treated area until it has been watered in, as they often still need watering in so that the fertiliser or weedkiller actually works. This normally applies to fertilisers rather than weedkillers, as the nutrients in them need to soak into the lawn. Weedkillers may need time to affect the leaves of weeds before they are washed into the soil.

Conversely, the supplements often cannot be applied to a lawn if it is too wet - or too dry - or in direct sunlight. Frequently, they will need using several days after a cut and several days before the next one so, if the grass is being trimmed once per week, apply the supplement in the middle of that period, giving the lawn several days to grow before applying them and several days to absorb them before cutting.

Different Types of Fertiliser and Weedkillers

There are a variety of different lawn supplements on the market and there are differences between them, as they are often designed to be used at different times of the year and to do different jobs. Some supplements will simply fertilise the lawn, others are designed to kill weeds and moss and yet more will combine both of these functions.

Consequently, outside the seasons in which a particular type of fertiliser or weedkiller is used it may be harder to find it for sale or, a rather better outcome, it may be sold at a discount. In the latter case it will need storing until it is used then.

Other products may be more designed for patch repair, and are used on areas of the lawn where the present grass is in poor shape, whether because it has been worn away by regular use or because weeds have throttled the grass that was there and then been eliminated to name a couple of reasons. Shady, sunny or wet areas may have suffered damage due to the conditions being less than idea for the strain of grass that was there.

How is the Fertiliser or Weedkiller Applied?

Once the amount has been determined, and a suitable type of supplement chosen for your needs, it will then need applying to the lawn. Some containers, usually the smaller, plastic ones, rather than the large bags of weedkiller and fertiliser, come with a built in spreader. With these they are simply help whilst you walk across the lawn and the supplement is then distributed. This doesn't tend to do it that evenly, as it is affected by how constant your pace is and being able to walk paths at the required distance apart. Patch repair kits will naturally only need applying in the areas that are patchy, rather than over the entire lawn.

For applying larger quantities over larger areas of grass a seed and fertiliser spreader is a possible alternative, which come in different sizes. These can distribute the supplement more evenly, and can be easier to use than the container the supplement comes in, if it does. Those without a built-in dispenser will require some other method of applying the, which could be just reaching into the container or bag of supplement and scattering it by hand, although this method increases the likelihood of the supplement getting somewhere it shouldn't and tends to give a rather uneven distribution.