Flour As Fertilizer: How and When to Use It

Wheat flour can be added directly to the soil, it is high in nitrogen. Flour can be used sprinkled around plants to deter pests or composted to use as soil amendment down the road. 

Flour is easily attainable and can be used in nitrogen-poor soil like clay. 

Flour As Fertilizer: How and When to Use It

Can Flour Be Used as Fertilizer

Flour can be used as a fertilizer in the sense that it improves the composition of some types of soil. Flour can improve soil texture and nitrogen levels in the soil. This is important for plant health. 

Nitrogen-poor soil is often hard-packed or clay, but any soil can be nitrogen poor. The best way to tell the level of nitrogen in your soil is to use a soil test kit and get actual levels measured. 

You can order these tests online or more detailed analyses are often available at your local agriculture department. Find information on your state website about soil testing. 

If you have nitrogen-poor soil, the flour will be a good fertilizer for your garden. It is recommended that you spread the flour over the dirt and then mix it with the soil. Because the particles are so small the flour will break down quickly. 

Flour can be mixed into the soil just like other kitchen scraps or other finely ground food products like alfalfa, corn meal, or nut flour. 

These products may improve the soil and would be classified as soil amendments rather than fertilizer by most gardeners.

Flour can attract rodents so mixing it well with soil or compost can help keep them from being attracted to your plot. 

When To Use Flour As Fertilizer

Flour is a good fertilizer or soil amendment for nitrogen-poor soil like clay. Flour is an organic soil amendment so it will help aerate the soil and add nitrogen. 

If you have hard soil, adding amendments should be part of your preparation before planting. Use organic matter like flour, alfalfa, peat, or leaves to add nitrogen and soften the soil. 

Hard-packed or clay soil needs to be aerated before planting to allow your plant’s roots to grow and to allow water to penetrate the soil. 

Flour can be applied at any time after it has been composted in a mixed compost or alone. Flour breaks down in less than 30 days in a compost environment so it can be composted very quickly. 

Flour can also be used to deter pests like grasshoppers.

If you have trouble with pests in the garden, flour can be used to deter them. Grasshoppers and other chewing insects can be stopped with flour dusting. 

You must dust the plants with flour and the gluten in the flour will become like glue in the mouth of the insects and stop them from being able to chew the plants. 

After 2 or 3 days rinse the plants well to remove any remaining flour. 

You may have to repeat this process a few times during the season, but it is a well-established way to manage chewing insects. 

Flour can also be used on rose bushes and other plants to get rid of aphids. Aphids can be very stubborn so a simple remedy is welcome. 

To treat pests with flour you should dust the plants with flour with a standard flour sifter or garden duster. 

The flour should be rinsed off the plant after 2 or 3 days and reapplied as often as needed until the aphids are no longer present. 

This gardener found flour effective after just a few applications. 

How to Compost Flour

Flour is safe to compost and breaks down quickly. Flour should be sprinkled in layers into the compost pile to prevent it from becoming gummy. Flour can be composted alone, but should be composted dry rather than wet to improve the rate of breakdown

This gardener did a very comprehensive experiment composting flour in her composting bin. Her experiment indicates that composting dry flour is better than wetting flour before composting. 

If you are composting flour, check to be sure there are no weevils in the flour. These pests often develop from eggs that are present in the wheat when it is ground into flour in the mill. 

It is recommended that you freeze any flour that may have weevils before composting. 

You can avoid any issues with weevils and weevil eggs by freezing the flour for three to seven days at 0 degrees Fahrenheit.  

If you find that your flour has weevils it is generally safe to eat, but very unpleasant. Use that flour in your compost instead. Grow new food with it! 

When composting flour in an existing compost pile you can sprinkle it in layers with other kitchen scraps or leaves to prevent the flour from forming clumps. 

The bag that flour comes in is also compostable, but it should be shredded and added to the pile rather than thrown in the unopened bag. 

Flour grains are so small that they are composted very quickly. Some have seen a pile of dry soil compost in as little as 15 days. 

Using Flour to Improve Plant Health

Flour is a good soil amendment to improve nitrogen in the soil. Nitrogen-poor soil may produce plants with overall yellowing, stunted growth, or odd root-to-shoot ratios. If you notice that your plants are not growing well, consider adding flour to your soil. 

Wheat flour is simply an organic soil amendment that can help aerate and improve soil texture. 

Flour as Soil Amendment

Flour can be added directly to your soil to help with soil texture. 

Wheat flour can work for this, but any finely ground organic material can work. 

Nut Flour

Rice Flour

Corn Flour

Bean Flour



All of these soil additions can improve the nitrogen in your soil as they will break down quickly because of the small size of the particles. 

Compost Flour

Composting flour makes it a rich fertilizer for your garden. Flour’s physical properties make it compost quickly. 

You can also add flour to an established compost pile and it will incorporate in just a few days.

Compost is already high in nitrogen, so adding compost will increase the nitrogen available to your plants. 

Check PH

Nitrogen uptake may not be optimal if your soil PH is 4 or lower. 

Checking soil PH is pretty cheap and easy and you can alter the soil PH with many inexpensive soil additions. 

Consider adding potash or burned leaves to low PH soil to raise the PH and improve nitrogen uptake. Ashes of any kind raise the PH of soil. Be sure to check the soil after the addition of these amendments to be sure the level is good for your crops. 

Fertilizing plants with nitrogen-rich flour can be an easy and inexpensive way to improve your plant health. 

Where to Find Expired Flour

Expired flour may be cheap or free for your garden or your compost if you know where to look.

Check these areas before laying out any cash for flour for your garden.  

Your Pantry

Check the dates on the flour in your pantry. If any are past their prime, turn them into new food by adding them to your garden. 

It is good to keep checking the flour in your pantry because it may contain weevil eggs which can hatch and spread to your other pantry items. So keep an eye on your flour for bugs. 

I know that I often have small amounts of specialty flours left over from recipes and special diet attempts. They are often expired and usually get thrown away. Composting these flours is a great way to use them. 

Flours of all kinds can be composted.

Grocery Outlets

Speaking of expired flour, grocery outlets often have expired flour on the shelf. If you bring them to the manager they may allow you to buy them at a discounted price. 

Our local grocery outlet puts flour on sale fairly often. 

If you have a large aphid problem or you are interested in adding a lot of flour to your compost you can also ask about a deal for buying in bulk for a discount. 


If you have a local supermarket you may have luck by asking them if they would be willing to donate expired flour. 

This is a great option if you are gardening for a nonprofit or community garden and you can provide them with donation documentation. 

Brave dumpster divers can also find plenty of good composting materials at grocery stores. 

Be sure to check local laws concerning dumpster diving as it is illegal in many areas. 

Buy Nothing Groups

Post an “In Search Of” post in your local Buy Nothing groups to see if any of your friends or neighbors have any expired flour to pass along. 

This is a great way to get free flour to add to your soil or compost pile.