Can I keep adding to my compost pile?

composter with scraps added on top

QUESTION: Can I keep adding to my compost pile? How do you know if it’s ever finished? – Randy F

ANSWER: Yes, using the cold, or passive composting method, also known as the add-as-you-go method, you can continue to add kitchen waste to your compost pile gradually over time. Because you are choosing to add waste here and there over time instead of making a batch of compost all at once, it’s going to take a lot more time for the organic material to decompose.

Cold compost takes longer to mature because the pile is not able to heat up to adequate temperatures due to daily or weekly additions to the mixture. Eventually, the compost will finish and mature in an add-as-you-go compost pile, it will just take a little bit more patience and time to get there. 

When creating an add-as-you-go compost pile, it is important to alternate between adding green and brown materials as best you can in order to balance out the carbon-nitrogen ratio in your pile. Those who use the add-as-you-go composting method are often adding kitchen scraps, or green compost materials to the pile.

So it’s a good idea to keep a bit of brown compost materials on hand nearby so that you don’t forget to add in some carbon-heavy materials to balance out the nitrogen-heavy kitchen trash. Every time you add a layer of food scraps, that layer should be covered by brown materials.

Leaving kitchen scraps uncovered on the top of your compost pile will attract rodents and insects and create a foul odor in your compost bin. Some brown materials that you may want to keep on hand to layer on top of food scraps are leaves, straw, hay, sawdust, and peat moss. Scraps can also be covered by a layer of finished compost. 

If you notice that you are composting too much green material and not enough brown stuff, it is a good idea to allow leaves, grass clippings and weeds to dry out before adding them into your bin or pile. Allowing these materials to dry out changes them from green materials to brown materials. Use a shovel, garden shears, or a machete to cut garden debris into small pieces to speed up the decomposition process. Large pieces of kitchen trash should also be chopped into smaller pieces before adding to the mix so that they will break down faster. 

Two important factors for successful composting include moisture levels and air circulation. Microorganisms that exist in a compost pile are most effective when moisture levels are consistently damp, similar to a wrung-out sponge, and there are plenty of air passages to help promote good air circulation. Decomposing organic matter will use up oxygen much quicker than water, so it is necessary to keep new oxygen flowing into your compost by turning or mixing the ingredients of the pile occasionally to keep circulation high. 

Compost piles should be large in size and volume. Commercial bins are usually somewhat small, but are made to allow air flow and retain heat and moisture, making them perfect for add-as-you-go composting. Turn your compost pile around once per week to help mix up brown and green materials. Each time you turn your compost, add a shovelful or two of finished compost from the bottom of the pile to the top. 

Stockpile valuable ingredients that you can add to your compost mix throughout the process. Compostable items that you can stockpile include fallen leaves, dead-headed flowers, weeds without seeds, and kitchen scraps stored in airtight containers. At some point during the year, you will find yourself short on either brown or green materials, and you will be thankful to have a stockpile to use when situations like this occur. 

Add-as-you-go compost piles will struggle to reach high temperatures that significantly speed up the decomposition process. However, if you have compiled a mixture with a good balance of carbon and nitrogen, provided a large surface area, regularly turn the pile, and keep the mixture slightly moist but never soggy, the temperature of the compost pile will rise high enough to encourage decomposition.