Guide to hot composting: how to get the best garden compost in just four weeks

Hot composting has become a bit of a trend lately. Buy one of the new hot composting bins and you'll soon see why. It lets you make high-quality compost at home in weeks. It's so simple to do and rewarding too when you feed your own garden with something nutritious that you've made from scratch yourself. No more carting heavy bags of compost home from the garden centre either. You can also make your own hot compost heap if you don't want to invest in a bin. This method requires a little more time and diligence, but it's pretty straightforward too.

Composting is a great way to be more sustainable, help the planet and cut down on waste. Plus of course it's a wonderful way of feeding your garden with the nutrients it needs to stay looking good. If you've already used our guide on how to compost to make your own cold compost, it could be time to switch up the action. So if you want to give hot composting a go at home, keep reading for our easy guide.

What is hot composting? 

As the name suggests, it’s all about the temperature. Let's start with cold composting first, which is the more commonly used method you might be more familiar with. This involves slowly adding organic matter to a compost heap and leaving it to break down in its own time. Hot composting refers to a method that produces compost in a shorter period of time stimulated by warm temperatures in the heap. While cold composting is the easier method, many gardeners say that hot composting produces better results.

What can you use to make hot compost?

Now for the science part. Your ideal compost mix will need to be 25 parts carbon to one part nitrogen. Although this sounds tricky at first, getting the right mix is easier than you might think. 

Typical ingredients that are rich in carbon include the likes of shredded paper, straw, twigs and dry leaves and these will form the main bulk of your compost. For the nitrogen elements, things such as grass clippings, fruit and veg scraps, garden waste, coffee grounds and chicken or farm animal manure are all viable options. 

How long does it take to make hot compost? 

If you get it right and follow the formula you'll see great results in as little as four weeks. As long as you monitor the compost and record the temperature everyday (more about that later), plus turn the compost every four to five days you'll be on the right track. After one month, you should have turned the pile four times. By this point, most of the pile will be a dark, crumbly compost. Now you must let it rest for a couple of weeks before you can start using it.

Top tip: It's best to place your compost heap or hot compost bin in a spot where it will get the most sun. Shady spots won't benefit from the added heat you'll get from the sun. 

Is hot composting better than cold composting?

The main benefit of hot composting is the speed at which waste becomes compost. A traditional composting bin can take anything from six months to two years to transform waste into compost. Hot composting can take as little as four weeks to produce compost. 

However, although the process of cold composting is slower, its low maintenance method can be appealing to many people as there's little that needs to be done to create your compost. On the flip side, many shop-bought hot composters such as HotBin (opens in new tab) can take a wider range of home and garden waste than you could use in producing cold compost, including meat and chicken bones, so it's a good way to ensure food and garden waste can always be put to good use.

How to use a hot compost bin

If you like the idea of hot composting, but don’t have the time to spare to make your own heap from scratch, it might be worth investing in a hot composting bin, which helps to simplify the process. The bin maintains a steady temperature of 40 to 60˚C, even in winter. All you need to do is regularly add food or garden waste, and a bulking agent or shredded paper to keep the air flowing inside the bin. 

How to make hot compost – a step-by-step guide

1. Mark out space for a pile that is at least 120x120cm. Alternatively, invest in a hot compost bin to make your compost in.

2. Have all your organic matter to hand at the start. Chop up the ingredients. An easy way to do this is to run the best lawn mower over them a few times. It's important to chop everything up so that it breaks down as quickly as possible.

3. Add a couple of shovelfuls of ready-made compost that will work as an ‘activator’ to kick start the process, then mix all the ingredients in a pile or bin.

4. Add water so that all the ingredients are evenly moist.

5. Maintain the compost heap by keeping an eye on the soil temperature and moisture. The pile should heat up within 24 to 36 hours. Between 60 and 68˚C is the ideal temperature. You can monitor this with a compost thermometer (opens in new tab). Some of the bins have an integral monitor in the lid to make it easier for you to keep an eye on the temperature.

6. When the pile starts to cool it's time to turn it to aerate the contents. This restarts the microbial activity and gets things 'cooking' again.

7. In terms of moisture, if the compost is looking too dry, give it water. However, if the pile starts to smell unpleasant, it's probably because it's too wet. Adding shredded newspaper or another high-carbon material will soak up any excess moisture. If rain is due, cover the pile with a tarpaulin to stop it becoming waterlogged.

8. After about two-three weeks of following this routine, you should have dark brown, crumbly compost. It's important to let it 'rest' for a further two weeks before using it.

The best compost bins

Not quite ready to give hot composting a go and prefer the idea of sticking with the more traditional method of making cold compost? Check our these latest deals on compost bins. 

Read more: 

• How to make leaf mould: turn fallen leaves into a rich soil conditioner
• The best compost bin: find the perfect design for your needs
• 5 ways to make better compost: improve yours with our top tips