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GARDEN GUY: Effective composting

Ihave been trying for years to compost. It’s not working. It usually takes too long, sometimes it smells and I never get a nice product like you buy in the packages. I even went to a workshop and received a large black bin to do my composting. Even that doesn’t work. What am I doing wrong?

There are a few important principles to know about composting that will make life a little easier.

By following some simple rules, you can speed up the processing time and produce good compost in one month to six weeks. Some ‘experts’ can even turn a pile of garden waste into nice compost in as little as 14 days.

Here are the points:

• Correct moisture and air (oxygen) content: Compost works best if the moisture content of the materials is about 50 percent. That’s not easy to measure, but it has been estimated to be about the moisture content of a wrung-out sponge. If the material is too dry, decomposition will stop; if too wet, oxygen is excluded and decomposition will slow and odors will be produced.

• Proper carbon/nitrogen ratio: For effective composting, the raw materials must have a proper carbon/nitrogen ratio — set at about 30:1. Since this cannot be easily measured, experience has shown mixing equal volumes of green plant material with equal volumes of brown plant material will give this ratio. The greens are fresh moist materials such as grass clippings, weeds, manures and kitchen scraps. The browns are dry materials such as twigs, wood chips, straw, saw dust and paper. If a pile of twigs are thrown to the side, they will eventually decompose. But when leaves (greens) are combined with the twigs (browns) in the proper ratios, the organic matter will decompose more quickly.

Mixing something such as grass clippings with twigs or chips is not only good for obtaining the proper ratio, but also helps maintain a good oxygen level. Grass clippings alone (shredded paper, too) tend to mat and exclude oxygen. Adding twigs helps open the pile, allowing a better movement of air.

• Proper size of material: Soft, succulent plant tissue doesn’t need to be chopped into small pieces because it will decompose rapidly. However, the harder to decompose woody materials will compost best if pieces are 1/2 to 1 1/2 inches in size — the smaller the pieces the quicker the decomposition.

• Proper pile size: The size of the compost pile is important. The minimal size is 3 cubic feet (3-by-3-by-3). Maximum size would be about 5-by-5 and as long as you want it.

• Proper turning: Turning the pile is not required, but will certainly speed up the process; turn any time from every day to every 10 days. Turning helps ensure proper air circulation, moisture and heat distribution.

Finally, here’s how to know when the composting is finished: when the majority of the pile has become dark, loose, crumbly and sweet smelling. Also, the original ingredients will not be recognizable with the exception of a few pieces of tough woody material.

Composting is a good way to reuse our natural resources, recycle nutrients and add good organic matter back into the soil.

Hi, Dr. Sakovich. First, thank you for your informative articles. Kudos to the person who developed and shared the carpenter bee trap. It works well and has prevented further borings into the woodwork of my home.

Quick note

Just an early note to mark your calendar for 9:30 a.m.-12:30 p.m. Saturday, Oct. 11. I will be teaching a gardening class at the University of Hawaii campus titled “General Care of Backyard Citrus and Avocado.”

Call CCECS at 974-7664 to reserve a seat.

Hilo resident Nick Sakovich is a professor emeritus of the University of California. He has worked in the field of agriculture for 30 years. Email your questions to Sakovich at askthegarden You also can visit his website at


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