Can You Put Toxic Plants in Your Compost Heap?

Utilizing a compost heap for food and yard waste is an excellent way to reduce waste, but it is also an excellent resource for strengthening your soil and fertilizing your plants naturally. Everything that goes in the compost breaks down naturally over time, but is it okay to put toxic plants in your compost heap? 

You can put toxic plants in your compost heap. As the plants break down, the poisonous chemical compounds break down too. After 50-100 days, the toxins are almost undetectable, but you can speed up this timeframe by cutting large stems and leaves into small pieces before composting them. 

The rest of this article will give you more information about how toxic plants can affect your compost heap, some poisonous plants to look out for, and an overview of how the composting process works. I will also share some common home uses for your compost heap. 

How Toxic Plants Affect Your Compost Heap

Most toxic plants have chemical defenses that make up the toxins that make them inedible or poisonous. These chemical defenses are broken down during the composting process, eliminating the toxic factor over time

Some plants take longer than others to break down fully, but after 50-100 days, the toxic properties are practically undetectable, according to a study by the University of California.

If you want to speed up this process, you can cut up the larger parts of the toxic plants like stems and leaves. Smaller pieces break down much faster than larger ones.

One of the biggest concerns when adding toxic plants to your compost heap is how the toxic plants will affect the soil and other plants in the heap. The good news is that if your compost pile is appropriately maintained, you do not need to worry about toxins spreading to the soil or other plants.

To properly maintain your compost heap, you need to mix it well and keep it moist (not too wet!). It is also important to keep it in a contained, designated area. 

Which Plants Are Toxic?

It might surprise you to know that many edible plants actually contain toxic or poisonous elements, whether it be in their stem, leaves, or another component of the plant. These plants are all perfectly safe to compost, but it is important to ensure the composting process has broken down the toxic elements of the plant before reusing it elsewhere. 

Here are some of the most common plants with toxic elements:


Rhubarb stalks are perfectly safe and delicious – but their leaves have high concentrations of oxalic acid and are considered toxic to both animals and humans. 

Potatoes, Eggplant, Peppers, and Tomatoes

These common garden vegetables are eaten regularly all around the world, but their leaves and foliage actually contain steroidal alkaloids that can cause nausea, diarrhea, or even more severe reactions.  


While beautiful to look at, daffodils are not intended to be consumed. Every part of this flower contains lycorine, a toxic chemical that can cause vomiting, nausea, and pain. 


Foxgloves are gorgeous, bell-shaped flowers that usually grow in colors ranging from white to pink or purple. Found commonly in gardens, these plants are very poisonous to humans when ingested.

Additionally, foxgloves are known to cause adverse reactions by touch – so be sure to wear gloves if you are handling these toxic beauties! 

Easter Lilies

Easter lilies are lovely white lilies that are often used in bouquets, but be careful to avoid the sap from the stems and leaves, as it can be toxic to humans. Lilies are also harmful to cats, so you may want to keep these out of the house if you share your home with a furry friend. 

Cherries, Peaches, Plums, and Apricots

While delicious, these juicy fruits contain a pit that has cyanogenic compounds. These compounds are used for making cyanide and can be deadly. These compounds are only a danger if the pit is chewed, smashed, or broken; a whole pit poses no threat on the outside. 

It might be a bit alarming to know that so many of the fruits, vegetables, and other plants we grow have toxic elements, but you can rest assured knowing that people have been consuming and growing these organisms safely for generations. 

When proper care is taken, we can use the safest and most wonderful parts of these plants and compost the rest! 

How Does the Composting Process Work?

We know that over time, old plants, weeds, grass clippings, and even food can be broken down to create a healthy supply of compost – but just how does this process work? If even toxic plants can be composted, what happens during the composting process that removes those toxins?

As soon as your banana peels hit the compost heap, tiny microorganisms get to work like a compost army, feeding on the organic matter and breaking it down until nothing is left but the basics. 

In order to successfully break down the matter, microorganisms need oxygen. This is why it is essential to stir or “turn” your compost pile regularly. The movement introduces oxygen into the tiniest parts of the compost heap, allowing every bit to be broken down. 

Another critical component of the composting process is water. Water is necessary for microorganisms to live, so it is necessary to water your compost heap regularly. That being said, you do not want your compost heap to get too wet, so bear this in mind when choosing the location for your heap. 

You’ll want to maintain a warm, moist atmosphere and avoid exposure to excessive rainfall. The ideal temperature for your compost heap is about 140-160 °F (60-72 °C). You can successfully maintain this temperature by choosing an ideal location for your heap, turning it regularly, and preserving a moist, not wet, consistency. 

To summarize, the composting process works by:

  • Microorganisms eat the carbon waste, breaking down the organic matter.
  • The organic matter returns to basic parts.
  • Oxygen provides the microorganisms a thriving environment to eat.
  • Water helps microorganisms live and multiply.

Uses for Your Compost Heap

Having a compost heap at home is a fantastic resource for waste reduction, successful gardening, and lawn maintenance. 

Here are some of the most common uses for compost:

  • Fertilize your garden or lawn.
  • Use it as mulch in your garden beds.
  • Mix with soil as a soil amendment.

Compost makes a fantastic organic alternative to many store-bought fertilizers, soils, and other gardening support tools.

Let’s dig deeper into some of these common uses:

Fertilize Your Garden or Lawn

To fertilize your lawn, you can sprinkle a layer of compost 1-2 inches thick (2-5 cm) over the grass and use a rake to combine it well so that it can get into the roots. Using compost as a fertilizer for your lawn can help heal any problem areas and improve the overall quality of your grass.

When using compost to fertilize your garden, you can make what’s called a “compost tea.” By soaking the compost in water for several days and then draining the water, you can create your own organic fertilizer to spray or pour over your plants.

Use Compost as Mulch in Your Garden Beds

Mulch helps maintain moisture, provides essential nutrients to your plants and soil, and can even help prevent weeds from growing. Compost is an excellent mulch medium and can be placed in your garden beds to encourage a flourishing garden. 

Starting at the base of your plants and working your way out about 12 inches (30 cm), put down a layer of compost about 2-3 inches high (5-7 cm).

Mix With Soil as a Soil Amendment

Soil amendment is the process of creating healthy soil to provide the most nourishing environment in which your plants can grow.

To amend your soil, you can mix in or layer compost on top, which will naturally aerate and add nutrients to the soil. This process will improve the health of the soil for your current garden and for years ahead. 

For mixing, you should work with half compost and half soil. This method is also excellent for creating your own potting soil if you’re not working in a large garden. 

If you elect to spread the compost over the top of your garden soil, you’ll need to keep the compost to an even layer of about 3 inches (8 cm) high or less. 


Any organic material, toxic or not, can be composted successfully. The poisonous materials will not negatively affect your compost heap because the chemical compounds that create the toxicity will also be broken down throughout the composting process.

Cut up any large elements like long stems or broad leaves in order to speed up the composting process and reduce the toxicity levels faster. 

You can use your compost heap to improve the quality of your garden, potted plants, and lawn, all while helping to reduce the amount of waste in your community!

Alexander Picot

Alexander Picot is the founder of and its lead content writer. He created the website in 2022 as a resource for horticulture lovers and beginners alike, compiling all the gardening tips he discovered over the years. Alex has a passion for caring for plants, turning backyards into feel-good places, and sharing his knowledge with the rest of the world.

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