(12 customer reviews)

Original price was: £128.99.Current price is: £109.64. inc VAT

FREE Delivery by Tuesday, 23 July, 2024.

The Thermo King compost bin uses Thermolene technology to insulate your compost, speeding up the process and producing good quality compost faster. Your composter will arrive flat packed for quick assembly and is manufactured from 100% recycled plastic.

This item: GARANTIA® 900L THERMO-KING composter
Original price was: £128.99.Current price is: £109.64. inc VAT
Original price was: £128.99.Current price is: £109.64. inc VAT
Original price was: £27.19.Current price is: £22.99. inc VAT
Do I need a soil fence? The soil fence prevents any rodents or small animals from burrowing under and into the composter. A soil fence isn’t needed but if you have any rodents or other small animals in your area then it might be something you will need to consider.
Length: 1000mm - Width: 1000mm - Height: 1000mm
Product price
inc VAT
Additional options total:
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Order total:
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SKU: 626003 Brand:


  • Thermolene promotes fast composting due to optimal aeration system and thermo walls
  • Easier filling with two large filling hatches
  • Cover lock to regulate air circulation
  • Easy assembly without tools
  • Made from 100% recycled material (PP)
> Product Manual

Free Delivery

  • Delivery lead time is 4-6 working days on all orders however for our large underground rainwater tanks please allow 7-14 days.
  • Price is included to mainland UK, quotations for highlands and islands available on request.
  • We use a number of different hauliers and also deliver on our own vehicles.  We try to provide a tracking number for all orders but can accept customer enquiries by phone and email if you don’t receive a tracking number.
  • Decorative water butt orders will be palletised curbside deliveries.  The customer being home to accept the delivery is advised but not essential.


You have 30 calendar days to return an item from the date you received it. To be eligible for a return:

  • Your item must be unused and in the same condition that you received it.
  • Your item must be in the original packaging.
  • Your item needs to have a receipt or proof of purchase.


Once we receive your item, we will inspect it and notify you that we have received your returned item. We will immediately notify you of the status of your refund after inspecting the item. If your return is approved, we will initiate a refund to your credit card (or original method of

You will receive the credit within a certain amount of days, depending on your card issuer’s policies.

Additional information

Weight 21 kg
Dimensions Length 1000 mm x Width 1000 mm x Height 1000 mm
Colour/ Material



3 Years


900 Litres

12 reviews for GARANTIA® 900L THERMO-KING composter

  1. Karen Forrest

    I’m very impressed with the service. Delivery was fast and goods were well packaged. Assembly of the 900l ThermoKing was child’s play, easily doable for one person. I did 3 in 20 minutes on my own. They appear extremely sturdy now they are put together. So impressed that I’m about to order another 10. We have 4 acres of mature land and our gardener will have them discretely dotted around. Highly recommended!

  2. Louise

    I have had my Thermocomposter for nearly 2 years, its excellent, really effective. It’s in a shady part of the garden but generates plenty of heat and is working well, it’s amazing how quickly it breaks down the garden waste

  3. Peter

    Bought 2 of the GARANTIA® 900L THERMO-KING composters (thanks for the discount on the second!). It took much longer to clear the old composting area in the garden than to assemble and fill these 2 composters. Assembly was straightforward. There was some excess plastic on 4 of the assembly points. Easily trimmed with a not too sharp knife. Now one composter is full and noticeably warm after only a couple of weeks. Second one is half full. Only one issue with them. Only one of the boxes had assembly instructions (it was the second one that I openend of course). However, it was easy to work it out. Ordering was easy and delivery quick and on time.

  4. M J Sprague

    A little fiddly to assemble single-handedly but quite doable. The Garantia 900L Thermo-King composter certainly looks impressive and is already being used. Time will tell as to how well it produces compost but I am certainly optimistic that it will do a good job.

    • Garden Tech

      We appreciate your feedback and are delighted you’re happy with the GARANTIA® 900L THERMO-KING composter.

  5. Paul Thompson

    Very happy with the Thermo King 900l composter. Good product, quickly delivered and easy to assemble. Now gradually filling and looking forwards to the compost. Used some of the old compost from our previous bin to seed this and ensure the worms were present in good numbers.

    • Garden Tech

      Your positive feedback motivates us to keep delivering excellence to other gardeners. Thank you Paul!

  6. Marilyn Mills

    Excellent product. It’s early days yet but I’m very happy with the sturdiness and large capacity of the bin. It appears very well made and built to last.

  7. Peter Wilson

    Marvellous compost bin, so much neater that open pallets and mesh. Really large capacity allowing plenty of material to be added. Very easy to put together and works extremely well.

  8. Andy

    It is perfect for my needs. Oddly enough it is living in my greenhouse at present, as I wanted it to use the heat generated to protect my seedlings and the flat top is perfect for resting my most most precious seed trays. Toms and cucumbers doing well! Thanks

  9. Sarah Woods

    The ThermoKing composter is a great product, delivered promptly. I ordered easily without having to set up an account too.

  10. Edmond Chau

    Efficient service and delivery. Easily assembled. I can’t commend on whether it gets high temperature yet as I only put it up a couple of days ago and we are in the depth of winter. The reason for 4 stars instead of 5 is the uncertainty of its efficacy.

  11. Andrew Sparling

    Bought two 900L THERMO-KING composter bins and now wish we’d bought a third! Easy to put together and seem strong. Hoping we get lovely compost.

  12. Andy Baker

    Very impressed, I invested in a compost thermometer at the same time of buying this and occasionally probe the contents. I have seen up to 60 degrees C inside this composter a couple of days after adding a fresh layer of shredded material which shows that the process is superbly effective at killing weed seeds etc. Great product and I would highly recommend it.

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How do composters work?

Composters, also known as compost bins work through heat, moisture, and air; where the bacteria breaks down the carbons 0f garden and food waste. Compost is very good for plants and can encourage growth, so it is no surprise to see more and more people making their own compost rather than store-bought packs.

Simply put the food waste or garden waste (lawn trimmings etc) into the composter, and assuming the material is biodegradable, eventually, over time this will break down to create a nutrient-rich mulch. This can then be put onto plants and borders, to help encourage growth.

What size compost bins do you sell?

Garden Tech stocks 280, 300, 400, 450, 600, 900, and 1000 litre composters.

How do I remove the compost from my composter?

Our compost bins have a small, easy access door at the bottom to allow you to collect the compost.

What is a soil fence?

A soil fence composter barrier will prevent rodents and burrowing creatures from getting into your composter while allowing worms and micro organises to pass freely between your compost and the soil.

What size compost bin do I need?

The size of the composter that you require is determined by the volume of vegetable material to be composted. A 300-litre bin is ideal for beginners, but large families and avid gardeners may wish to go bigger.

Do you have replacement lids?

Garden Tech can offer replacement lids, if requested.

How many compost bins do I need?

Many customers prefer having two compost bins as it also gives you a place to store finished compost to use in the garden as and when needed.

What size should a compost bin be?

In general, bigger is better, but 3 feet by 3 feet (1000mm x 1000m) is a manageable size for most gardeners. The compost bin(s) should be placed in full sun, if possible – shade will of course reduce the temperature and slow down the composting process.

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