Can We Compost Sunflower Seed Shells? How?

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In Brief: Can We Compost Sunflower Seed Shells?

Yes, you can compost sunflower seed shells but in limited amounts. The large quantities may take a longer time to decompose. The entire plant contains chemicals that may inhibit the growth of other plants. There is little research on whether the allelopathic chemicals of sunflower seed shells negatively impact the compost. Alternatively, they may be used as weed-suppressing mulch.

Are you looking to compost the sunflower seed shells?

If yes, you have come to the right place. This comprehensive guide will help you decide on it.

Let us learn more!

Can We Compost Sunflower Seed Shells?

Yes. You may compost sunflower seed shells but in moderation.

Few gardeners are against composting them as they release allelopathic chemicals. These chemicals may inhibit the growth of nearby plants. Also, they decompose slowly and so the chemicals may last longer in the pile.

There is limited research on composting sunflower seed shells. Future research will determine if composting sunflower seed shells have a negative impact. So, I would avoid composting large quantities of shells.

Also, many gardeners suggest a possible use of them as a mulch in an established flower garden. These may reduce weeds.

How To Compost Sunflower Seed Shells With Ease?

Collect the sunflower seed shells, rinse in water to remove the salt, and add to the compost bin. You may layer it with high-carbon plant waste to aid in decomposition. It takes a long time to decompose.

The sunflower seed shells, also called hulls are tough and fibrous. So, they take longer to decompose. The different steps in composting sunflower seed shells are mentioned below.

Prepare the sunflower seed shells – Collect the sunflower seed shells. You may wear gloves to protect your hands if collecting the shells from the bird feeder. Rinse them off to remove the salt if using shells from seeds sold for human consumption.

Add them to the compost bin – Throw them into your bin. You may crush them to decompose faster.

Layer them with other plant waste – Layer with high carbon matter, including grass clippings, pulled weeds. Some prefer to lie them on top of the already composting material.

Collect the compost – Allow them to decompose fully before collecting the compost. It may take some time to degrade.

Are Sunflower Seed Shells Allelopathic?

Yes, every part of sunflower plants is allelopathic. The sunflower seed hulls may carry some chemicals that inhibit the growth of the plants.

These chemicals may influence the germination, growth, and survival of the other plants. Future studies will determine the nature and effect of harmful chemicals from seed shells.

Are Sunflower Seed Shells harmful to the soil?

Sunflower seed shells release allelopathic chemicals into the soil that may be harmful to the growth of certain plants. But, these shells may be decomposed. However, they take a longer time to degrade completely.

These chemicals prevent the growth and germination of certain plants. You may not be able to grow plants sensitive to these chemicals in such soils.

They may be harmful to birds if coated with salt. However, the sunflower seed shells do decompose. But, they may take a long time to degrade completely.

One benefit is that they may be used as mulch to prevent the growth of weeds in established gardens. It may reduce the use of herbicides for sustainable agriculture.

Does Composting Reduce Allelochemicals?

Yes, the composting may degrade the allelochemicals due to the action of microbes. But more research studies are required to study the effect of composting on chemicals from sunflower seed shells.

There are no research studies available studying the degradation of allelopathic chemicals from sunflower seed shells during the composting process.

As the sunflower seed shells decompose slowly, these chemicals may last longer. They may degrade over a long time.

So, more research studies are required in the future.

How long does it take for sunflower seeds shells to decompose?

Sunflower seeds may take at least three years to decompose completely as they are tough and fibrous. They may be mixed with organic matter to fasten the process.

Some experts mention that sunflower seed hulls may take at least three years to decompose. They can be added to the compost heap but take a long time to decompose.

A research paper showed that co-composting of sunflower seed shells with organic amendments had better decomposition compared to others.

It is recommended to mix the sunflower seed hulls with organic matter to fasten the decomposition.


Are sunflower seed shells good for anything?

Yes. Sunflower seed shells make a good mulch as they reduce weeds. They work well in gardens and flower beds. It may also be used for the growth of fungi.

What is a sunflower seed shell made of?

The sunflower seed shell is made of lipids, proteins, and carbohydrates. The carbohydrate fraction is mainly made of cellulose that make it fibrous and indigestible. Avoid munching on sunflower seed shells as they may damage the digestive tract.

Bottom Line

Hope this article has answered if we can compost sunflower seeds.

Also, let us know your preferred method of composting sunflower seed shells!