How To Regenerate Spent Compost?

Compost is a wonderful addition to any garden. Well rotted, aged compost is excellent for providing nutrients to growing plants, plus it is a great way to use up your kitchen scraps!

However, like most things, compost does have a shelf life. How to regenerate spent compost is a great question to ask if you are wondering how to awaken your compost’s qualities.

Can You Add To Finished Compost?

There are a few different types of composting about these days, but the most common is the cold composting technique.

This is where you don’t make a batch of compost all at once, but simply add a few bits here and there and let the decomposing bacteria do their thing.

This type of compost is never really “finished” – the top layer, where you add more kitchen scraps and carbon based materials, continues decomposing, while the lower layer has already done so.

As long as you add your new compost offerings to the top of the pile, and use the underneath section to fertilise your garden, you can keep adding to your compost this way.

Using a compost bin for this method of compost is the best option,as they can retain a bit of heat and are a good size.

You can also add your scraps to the top and remove the compost from the door at the bottom using one of these.

Make sure you turn your compost relatively regularly, to mix up the materials you have. When you turn it, add a shovel of the compost from underneath to the top.

What Do You Do With Finished Compost?

Compost is a truly wonderful thing. Packed with nutrients to help your growing plants, it is the most natural of all the fertilisers.

However, you do need to check that it is completely ready before you use it on your garden, to avoid attracting pests or damaging your garden plants.

  • The texture should be smooth and crumbly. You might see the odd seed or stone that takes longer to break down, but in general there shouldn’t be any recognisable bits.
  • It shouldn’t smell offensive. Compost that is ready to spread on the garden should smell a little sweet, like a damp forest. Sour odours or the smell of ammonia are a sign that it is not quite
  • The colour should be dark. Compost is known as “black gold”, and when yours is done you will see why this is!
  • It will be smaller than when you started. Compost will reduce its overall size by about 1/3 when it has finished all that great decomposing.
  • The temperature of the pile should be similar to the outside temperature. A compost pile that is hot to the touch means it is still decomposing and needs to be left for longer.

Once your compost is ready, there are a great many things you can do with it:

Mix it with soil to make a good potting compost

Use 1 part compost, 1 part vermiculite and 1 part topsoil to make a great start for your seedlings.

Spread it over your flower beds

Using compost as mulch will not only give nutrients to the soil, it will also prevent evaporation and help to control weeds.

Make compost tea

For a concentrated shot of nutrients straight to your plant’s roots, steep compost in water to give them an extra boost.

Feed plants

Adding a bit of compost to the holes into which you will plant things is a great idea, as it means they already have some extra nutrients.

Improve lawns

Spreading a good 2 inch thick layer of compost on your lawn in the autumn is a great way to improve it for the next growing season.

Sprinkle it over garden beds

You don’t even need to dig in the compost; rains and worms will do it for you!

Dose fruit trees

It’s easy to forget about your large, well established fruit trees, but they too will benefit from a dose of compost! Spread it around the roots in early spring, before the buds have opened.

Use it to grow heavy feeders

Melons, cucumbers, squash, tomatoes and aubergines have large nitrogen requirements, and will thrive with a bit of added compost.

Can You Reuse Compost In Pots?

Compost can be resued, as long as it hasn’t been used to grow plants that became diseased. Tomatoes which have had blight can spread this for years through the soil, so never reuse this compost.

Compost can be stored easily in pots, and it actually makes a good solution for keeping your leftover compost that you don’t want to use right now.

Start by tipping out all your old compost onto a tarp, and sifting through it for old roots and weeds.

Let it dry out in the sun to prevent any mould from forming when you store it – it doesn’t need to be a dry as a desert, but removing most of the moisture is the way forward.

It’s a good idea to swap over your composts – the type that has grown flowers this year is best used for vegetable next year, and vice versa, to prevent disease spread.

Leaving it out in pots in the winter is a good idea, as the cold temperatures will kill off pathogens.

Here is a good video showing you the best way to reuse your compost in pots:


Can I Just Put Compost On Top Of Soil?

Spreading compost on top of the soil is not only good for the soil, but very easy work for you!

You can simply lay a 2 inch thick carpet of compost on top of the soil and leave it – the weather and various insects will help the soil absorb it.

Spreading compost on top of soil is not only good for adding nutrients, it can also improve the structure of the soil and help its moisture retaining properties.

Final Words

Now that you have a few ideas under your belt on how to improve your compost and keep even the most spent pile working, you can go forth and compost!

Keep your garden healthy and your plants thriving with the tips above – you can thank us later. And if you’re looking fore more composting advice, read my guide about ericaceous compost.

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