It is important to realise that not all mowers are created equal, and you need to have the right lawn mower for your type of garden. Apart from some mowers being much easier to use than others, different mowers also have a different impact on how your garden will look.
The key advantages of petrol lawn mowers is that they are both powerful, and highly mobile. A basic petrol lawn mower will have at least 3hp where as an electric mower will only have up to 2hp. This makes them capable of cutting through long, thick grass with ease, something an electric mower would struggle with. The other advantage they have over electric mowers is that they don't require a long power cable to be connected and dragged behind it. Depending on the size of your lawn this could be quite an important issue.
Petrol lawn mowers come in both the 2 Stroke and 4 Stroke variety. 2 Stroke lawn mowers are more powerful, less expensive, have a better power to weight ratio, and can be operated in any orientation. However, they are also louder, less fuel efficient, and do not last as long due to the high revving engine. They also require the petrol to be mixed with oil prior to use in order to lubricate the engine.
4 Stoke lawn mowers by comparison are not as powerful, but contain an oil sump (a separate oil chamber) and don't need the fuel to be pre-mixed. This saves the operator from mixing the fuel but it also means that the mower cannot be tipped on one side as it will cause the oil to fall out of the sump into the fuel chamber.
Electric Lawn Mowers (rotary)
The key advantage of an electric lawn mower is the price. A basic rotary electric lawn mower will cost you about half the price of a petrol mower, as well as being lighter, more quiet, and requiring less maintenance. As mentioned above the big disadvantage of an electric mower is that they lack in power when compared to their petrol based alternatives. Most electric mowers also use a power cord which can get in the way but there are also some that are battery operated and simply need to be charged over night.
For a small lawn an electric mower should do fine, provided you mow regularly. If it is any larger or if the grass tends to get out of hand then you will need the extra power of a petrol mower.
Cylinder mowers consist of a cylinder and a number of horizontal blades that spiral around it. If adjusted to the correct height a cylinder mower will give the best cut of any lawn mower. They are however, best suited to flat lawns and can be difficult to use on bumpy or tall grass.
The number of blades that spiral around the cylinder determines the quality of the finish. The more blades the better the cut. Cylinder mowers can also be fixed with a roller which flattens the grass giving a smooth finish. A cylinder mower with a rear roller will give the best striped effect.
Some cylinder mowers are entirely hand driven whereas others may have the blades driven by an engine. Self propelled cylinder mowers use an engine to propel themselves forward as well as to turn the blades. This can save the operator a lot of energy as little effort is required to move the mower around the lawn.
Maintaining a cylinder mower in good working order is typically harder than maintaining a rotary mower.
Hover Lawn Mowers
On a hover lawn mower the rotation of the blades creates a downwards draft and the escaping air lifts the mower off the grass making it hover a few centimetres above the ground. This makes it very easy to push around the garden and, providing that you are not interested in getting stripes, means that you can mow the lawn from side to side if you wish. Hover lawn mowers are cheap, light, and quiet. On the down side they are also quite low power and so best suited to small lawns that are mowed often. They typically come in electric but there are also petrol versions available. Flymo are some of the most common Hover Lawn Mowers.
Self propelled lawn mowers are typically petrol rotary mowers. They are self propelled in the sense that the engine powers the wheels making the mower move forward by itself. This saves the operator from pushing it and makes it far easier to mow a large lawn. The only downside to self propelled mowers is that they have less power as the output from the engine is split between turning the blades and turning the wheels.
There are generally two types of ride on mowers. Those with their cutting decks underneath the tractor, generally referred to as lawn tractors, and those with their mowing decks in front of the machine, often called zero-turn mowers because of their maneuverability. Mowing decks on ride on mowers are rotary and have two or three cutting blades. Deck width can vary in size anywhere from 38" to 54" and wider for commercial mowers.
There is a wide range of brands on the market that offer various features and engine size. A model with an engine output of 8.5HP would be suitable for a lawn up to one acre in size. If your lawn is larger than that then you should consider a model that has 11.5HP to 13HP as they will not have to work as hard to do the job.
By paying a more you will get a machine that can handle tough conditions as it will have been built with rugged conditions in mind. You will also get better features and a more comfortable ride which is a big consideration.