Is Homemade Compost Better Than Store-Bought Compost?

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Sydney has over 15 years of experience in lawn maintenance, landscape design, and organic gardening. She has an A.A.S. in Landscape Design/Organic Produce Production from the Nebraska College of Technical Agriculture.

What Makes Compost Good For Soil?

Compost is touted as a fix-all solution, but what exactly is it fixing, and how does it work?

There are two main properties of compost that make it beneficial for your garden:

Nutritional Value
Structure

The nutritional value of compost is dependent on the materials used. If a pile is built out of cardboard and grass clippings, the nutritional value will be slightly different than one built out of twigs and vegetable scraps.

If you build your own compost piles, you know what went into it, and you will know how balanced it is. However, although compost does provide some nutritional value, it is not enough to qualify as a fertilizer. So, although values can vary, most aged compost mixtures will be similar in nutritional value.

The structure of compost is generally uniform regardless of the ingredients. The properties of compost make it possible for soil to hold more water, air, and nutrients, which helps improve almost all soils regardless of the issue.

Can Compost Be Bad For Soil?

Surprisingly, yes. Compost is a good, not great, source of nutrients. However, repeated applications can cause phosphorous toxicity.

Plants need nitrogen, phosphorous, and potassium for most basic growth processes. These are usually listed on a fertilizer label as N-P-K, and given as a ratio, like 10-5-5.

Before you add compost to your soil, you should do a test to see what the nutrient content is, and determine the pH. Once you know the general properties of your soil, you can determine what you need to add. Bagged compost should have an N-P-K ratio on the bag, but homemade compost will need to be sent to an extension office for analysis.

If your soil is high in phosphorous, and your compost also tests high for phosphorous, you will likely end up with a toxicity if you use the same composting materials for each pile, and apply it yearly. This can show up in leaves as chlorosis, or yellowing.

High nitrogen issues are generally not a concern unless the compost has not aged properly. Nitrogen moves through soil very quickly, and excess nitrogen just washes away. This is not great news for local water sources, but it is better to have a little too much nitrogen from compost than a large excess from too much fertilizer.

So, what does all of this mean?

The goal of adding compost is to amend your soil. If your soil is lacking in nutrients, you want to add the compost that will adequately fix the problem. Adding too much is worse than not having enough since some vitamins and minerals are fixed in the soil and will build up over time.

If your homemade compost could cause toxicity in some area, try to find another use for it. Determine what your soil would need in order to balance its nutritional content, and find a compost mix that can properly amend your soil. If you want to make your own compost, continue to experiment with different mixtures until you find one that will adequately improve your soil.

Should I Use Homemade Or Bagged Compost?

It depends on your soil test, but homemade compost is better than bagged compost if you can safely add it without developing toxicities.

Most bagged composts will sit and become more dense, which makes them less helpful for improving structure. They can also leach nutrients if they become moist during storage. Plus, you don’t know what chemicals they may have been exposed to.

Homemade compost helps reduce the waste produced by your home, keeps organic material out of landfills, and it’s free. Plus, it’s fun to make and experiment with different mixtures and bins.

This does not mean bagged compost is harmful or bad for your garden; in fact, it is a great amendment if you are unable to build your own compost pile. But, if you have the choice, homemade is better.

When Should I Buy Compost Instead Of Using Homemade?

Even if your homemade compost is perfect for your soil, you may still need to buy some bags from the store.

It is difficult to make enough compost to adequately amend a large garden, lawn or landscape. If your soil structure is causing problems, it is better to buy compost than to keep growing in clay or sand. Over time, these additions of organic matter will gradually improve the soil, and you may be able to get by on homemade compost once the soil is holding water appropriately.

If you’re reinstalling your lawn, you will want to add a ¼”- ½” compost layer and till it in before replanting. For an average lawn in the United States, you would need between eight and sixteen cubic yards of compost. A large bag of compost is 3 cubic feet, meaning you would need between 72 and 144 large bags of compost for this task.

With this amount of compost, it is easier to purchase material by the truckload. Unless you have a large-scale composting operation in your backyard, this is one scenario where store-bought compost is a better option than homemade. Considering a home compost pile will shrink by at least half before it is finished, you would need a minimum of two dump truck loads of organic material to make the compost necessary to reseed your lawn.

So, while homemade compost is generally best, there are scenarios where store-bought compost is necessary. It is better to add store-bought compost than to avoid amending your soil adequately because you do not have enough in your own pile.

To learn more about building a compost pile, visit our articles on active compost piles, how to use different materials, like cardboard and newspaper, and how to determine which veggie scraps to leave out of your pile.