All through the cold weather, you have to defend the plants in your greenhouse from frost damage and one of the most ignored pieces of gear is a decent greenhouse heater. And the good news is is that you can pick up a decent heater for your greenhouse relatively cheaply.

Now dependent on your requirements, 'cheap' can still be expensive and you can safely assume to spend less or more depending on the size of your greenhouse. If you only have a smallish area to heat inside your greenhouse you can effortlessly pick up a greenhouse heater for the job for less than £30. If you have a bigger greenhouse or need a bit more humph, then the cost of a good greenhouse heater could run into the £100s. As you can see, you need to be pretty sure of what you require before putting your hand in your pocket, else you can end up spending more than what you really need to.

The insulation on most plastic greenhouse have quite a low insulation value and so the buying of the correct greenhouse heater is crucial to replace any lost heat. When extra heat is needed to retain the temperature at the precise levels, you're best off using a paraffin or electrical heater. In addition, a thermostat is vital to ensure you can accurately control the temperature within your greenhouse and fortunately, most variations of heater come with one already installed.

I'd rule out a gas heater as the initial cost in buying one can be a little too high. That's just my view, of course, and I certainly wouldn't advise you not get a gas heater based purely on the price, in fact, they can be a better option in the long term. 

The running costs of your greenhouse heater are an essential consideration. The current price per unit of electricity in the UK is about 15p (average) which will see the cost of your running a 1000w greenhouse heater to be rougly that amount per hour. A paraffin greenhouse heater, though, could cost twice as much for the same period of time. You do need, though, to take into account the fact that a paraffin heater manages to preserve it's heat for a period of time when turned off while an electric model is off when its off.

Personally, I go with electrical greenhouse heaters as I favour the upfront low-priced option for the models - I had only a small budget when I started and so the low-priced models and inbuilt thermostats meant I could exactly maintain the temperature with a small start up cost - again, though, that's just my opinion and you shouldn't be put off other options.

If you've ever wondered how petrol lawn mowers work, then you're not alone. With any luck what you read further down will help you answer the question. 

The similarities amongst the petrol lawnmowers you can buy (for instance, the Mountfield S461 PD) and the electrically powered mower are much the same. The foremost difference, of course, is the basis of the power that turns the cutting blades and, in some cases, the back wheels and / or rear roller. Unfortunately, more power means more money but if you look around you should be able to find some cut-price petrol mowers that are up to the job! 

Generally, a 4 stroke engine is attached onto a petrol powered mower which produces a decent amount of power for any sized turf. And the good news is most of these mowers use the same petrol you put in your car from the gas station. The combustion within the engine then powers the cutting blades of the mower which can either be rotary or cylindrical. 

Think of a rotary blade being the big hand on a clock. It rotates round cutting the lawn as it does. There are generally 4 cutting blades and they are designed similar to a planes propeller so that they suck up air. The difference in pressure that follows above and below the blade results in the grass being pulled up, somewhat, ready to cut. 

The cylindrical blade lawnmower works much like you’ll see on a combined harvester. The cylinder will turn over and over slicing at the blades of grass as it does. 

The following steps below will give a good indication of how mowers work : 

To fire the engine up, the operator typically tugs on a cord that starts things up. This is in all probability familiar to you if you've ever worked with a chainsaw or the engine on a speed boat. You may be fortunate to come across a petrol lawn mower with a starter key which is identical to how you start your car before a journey. 

Depending on the model of lawnmower that you use for your lawn, the engines purpose is to deliver power to a number of different features upon the lawn mower. Firstly, and most importantly, it will generate the power to the blades to rotate and cut the lawn. The less important role of the engine is to be responsible for drive to the back wheels of the lawnmower if you happen to have a self propelled model. Once more, there is a price you need to consider - the more an engine has to do, the more power it needs to produce which by and large means a bigger engine for the lawn mower. 

The engine is usually operated by a throttle that you'll find on the the handles of the mower. As ever more thottle is given, the engine will produce more and more power to be sent to the blades and / or rear wheels. As the RPM increases, so does the energy output of the motor. 

Once they have power from the engine, the cutting blades get to the task and capture the blades of grass in their grip and cuts them to the height that you have selected. The cutting height of the blades is determined by the model and is commonly between 20mm and 80mm. The is usually set by a small lever which grants a number of diverse settings. For a healthy lawn, its essentialto cut the grass to different heights during the cutting season - this is typically determined by the type of grass you have and how dry or wet the spring / summer is. 

To finish, we need to dispose of with the grass cuttings. Different mowers offer different options but all will offer a grass collection box of some type. The grass collection box is attached to the rear of the mower and collects the cut grass. Some lawnmowers also offer a discharge option where the cuttings are cleared from the mower to the rear but also, sometimes, to the side. Mulching is another option offered by some petrol lawn mowers. The lawn is cut into tiny clippings and then dropped back onto the lawn where they've just come from. These little grass cuttings will be broken down and in turn, help to fertilize the soil. 

And there you have it. You wanted to know how lawn mowers work, and there you have it. As with most things, there are devils in the detail, but as a rudimentary 'how do' article, that's how they work.