Grow Squash on a Compost Heap

What is it?

Because plants in the squash family grow happily in fresh, unfinished compost, some gardeners will build a compost heap and grow their squash plants right on top of it as it breaks down. This is also called a 'grow pile.' It is a great way to use up the leftover garden plants from a fall/spring clean-up, while also doubling up on functions in a limited garden space.

What style does it fit?

This style of compost heap takes no work after assembling, other than watering the squash plants, so it is a great fit for hands-off composters as well as gardeners of all kinds.

What space does it need?

The compost heap should be assembled in a garden.

Can you use it all year?

It works best if the compost heap is built in the fall or spring out of old garden plants, but kitchen scraps can be added over the winter as well. The squash should be planted in the spring after the last risk of frost, and no more material should be added to the pile after that.

How does it work?

Compost heaps rely on naturally present decomposers like bacteria, fungus, and bugs to consume organic material and transform it into humus, the organic component of healthy soil. This type of compost heap also takes advantage of squash plants' natural affinity for growing in fresh, unfinished compost. 

The basic recipe for building a well-balanced compost heap is the same as it is for a compost bin, with a couple of tweaks. For review of the basic recipe (nitrogen, carbon, water, air, and soil for microbes), check our link on compost bins.

The adaptions made to the basic recipe for this squash-growing compost heap are:

1. We add a lot more soil than normal - 10 to 20% of a pile by volume. This makes a denser compost mix, which helps keep the squash roots happy over the summer as the compost pile decomposes and settles. 
2. Because we won't be stirring the pile once the squash are planted, this can be a good system to include an aeration pipe. An aeration pipe is any piece of plastic or metal pipe with holes drilled along it, which acts as a passive source of airflow for a compost pile.
3. Finally, to help keep the pile damp without the help of a compost bin, we cap the pile with a few inches of mulch.

Assembly instructions:

• Build your compost heap. This can be done in the fall to prepare for next year or left until spring. Alternate thicker layers of nitrogen-rich material and carbon-rich material with thin layers of soil. If you have it, the leftover garden plants from the previous season of gardening make a great source of carbon-rich material for the pile. 
• Optionally, you can lay an aeration pile horizontally through the compost heap, several inches above the bottom, with one or both of its ends sticking out. This step is more important the larger the pile is.
• Once you are done building the compost heap, water it thoroughly, and cap it with several inches of mulch to keep in moisture.
• Make a hollow depression in the top of the pile. Fill this hollow with several shovels of soil. 
• Plant your squash seeds or bedding plants into the soil on the top of the pile. Water the squash well throughout the season, and enjoy your harvest in the fall!

As the squash grow, their roots will benefit from the nutrients, moisture, and beneficial microbes in the compost. The broad leaves will also shade the pile, helping keep it damp and cool. When the growing season is done, the compost heap can be raked out over the garden.

  

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Got more composting questions? Email the Compost Hotline at [email protected].