Can You Compost Flour?

Flour is a store cupboard essential for any keen baker, but if your foray into baking didn’t quite work out, you could be left wondering what to do with old flour.

Can you compost flour? Yes, you can add flour to your compost bin. All types of flour can be composted, including alternatives like almond and coconut flour. Old rancid flour is fine too.If the flour is infested with weevils, you can freeze it to get rid of them before you add it to your compost pile.

How to compost flour?

When flour gets wet, it becomes very sticky. If you add too much flour to a moist compost pile, it can clump and block air and water from circulating. A compost heap that lacks air and water will be a smelly one.

To prevent this from happening, only add small amounts of flour to your compost bin and mix it in thoroughly as soon as you add it. If you have a lot of flour to add, it’s best to space it out over a few days or weeks. 

Another trick you can use is to mix your flour in with something chunkier before you add it to your pile. Woodchips are perfect. Mixing the woodchips in with the flour gives it more texture and creates air pockets so oxygen can flow freely.

Can you compost flour bags?

The majority of flour bags are made from multi-walled paper, so you can add them to your compost pile. The bags can be several layers of paper thick, so it’s best to shred them before you compost them. Shredding the paper will speed up the decomposition process. 

Flour is packaged in paper because it’s a breathable material. Plastic would trap moisture within the packaging, which could cause the flour to mold. 

Although it’s unlikely, if you’re concerned that the flour bag might have a plastic lining (which isn’t compostable), a good test is to rip the bag. If the material tears cleanly and easily, then it’s just paper. If it’s hard to rip, then the bag probably has some sort of lining.

Can you add flour to a worm bin?

Yes, you can add flour to a worm bin but sparingly. The moisture in a worm bin can quickly turn big lumps of flour into impenetrable dough balls that the worms will avoid.

The best way to add flour to your worm bin is to lightly coat the surface and then spray it with water. The water helps to wet the flour and prevents it from sticking to the worm’s skin. 

Some people use their red wigglers for fishing as well as composting. For fishing, the bigger your worms, the better. Bigger worms also benefit your composting efforts because larger worms can eat more.  Wheat flour is often used as an ingredient in fattener recipes because it’s a good source of protein for the worms.

Is flour a green or brown composting material?

Everything you put in your compost bin can be classified as a green or brown material.

Composting materials are either brown (carbon) or green (nitrogen)

Green materials like grass clippings are high in nitrogen, while brown materials like dried leaves are high in carbon. 

Flour is a tricky one to classify. Some people say flour is a brown material because it’s a carbohydrate and dry. However, flour does contain protein (i.e nitrogen), meaning you could think of it as a green material.

There’s a wide variety of different flours, and each type contains a different level of protein. In general, the lower the protein percentage, the less nitrogen it contains, and the ‘browner’ the flour is. We’ve looked at data from the US department of agriculture to determine precisely how much protein is in certain flours, and therefore where they sit on the green to brown scale.

Here are our results:

FlourProtein %
Cake Flour7%
All-Purpose Flour11%
Bread Flour14%
Coconut Flour15%
Almond Flour20%

Alternative flours like coconut and almond flours have the highest protein percentage, while cake flour has the lowest.

Different flours have different nitrogen levels

Whether a material is green or brown doesn’t affect how well it will compost, but it’s useful knowledge because in order to compost effectively your pile needs to have a good balance of green and brown materials. For more information on how to get the perfect ratio, check out our comprehensive guide on how to compost.

How to make your flour last longer

If you know you’re not going to use your flour up before it goes bad, here a few tricks to help it keep for longer.

  • Transfer the flour into an airtight container such as a tupperware box or a mason jar. This will stop moisture from getting into the flour and causing it to mold.
  • Storing your flour in the freezer will help prolong its shelf life. All-purpose flour can last up to 2 years if frozen, but only 6-8 months if kept at room temperature. If you keep your all-purpose flour in the fridge, it will last around a year.
  • Putting your flour in the freezer also kills any weevil eggs that may have survived the manufacturing process. No one wants weevils hatching in their flour!
  • If you’re lacking room in your fridge or freezer, then try putting a few bay leaves in your flour. Weevils are said to hate the smell of bay leaves, so this should keep them out.

You’ll usually be able to tell if your flour has gone off by smelling it, or if you can see bugs.

Another use for old flour is to use it to make bird treats. Mix the flour with bird seeds and water, shape into balls and bake for around 20 minutes. Birds will be flocking to your garden in no time.