Many gardeners know that you can make your own compost at home from kitchen scraps and yard waste. However, some gardeners don’t have enough materials to make compost, or they just want to have some extra on hand for a bigger garden.
So, can you buy compost? Yes, you can buy compost online, at garden centers, from landscape design companies, or even from neighbors who have extra. You can buy compost made from yard waste and food scraps, composted manure, mushroom compost, or worm castings.
Of course, there are some cautions to keep in mind when buying compost. You should be careful about your source and how the compost was made. Let’s take a closer look at the types of compost you can buy, what you should look out for, and some examples of who you can buy from.
Can You Buy Compost?
Yes, you can buy compost in bags from online retailers or from garden centers at stores such as Lowe’s, Home Depot, or smaller chains. You can also order larger deliveries of compost from local landscape design companies, and they may also be able to deliver mulch or manure as well.
It is even possible that some of your nearby neighbors may have some extra compost lying around. It doesn’t hurt to ask, especially if you know some enthusiastic gardeners in your neighborhood! Even if they don’t have any extra, they might know a source that they are willing to share with you.
Before we get into the types of compost, let’s take a quick look at things that should not go into any type of compost.
What Should Not Go In Compost?
Before you buy any type of compost, have a look at the bag to find out what the ingredients are. If there is no label, ask the manufacturer (or landscape company) how the compost is made.
Often, the ingredients will tell you everything you need to know about the quality of the compost. However, there are also certain things that you should not see or smell in good compost.
Here are some warning signs of bad compost that you should avoid:
- The compost smells like ammonia (due to uncomposted animal waste), or has a rotten smell (good compost smells like fresh earth after rain).
- You can see large pieces of raw compost materials, such as straw, wood chips, sawdust, or grass clippings. It is ok to use these things in compost, but they should be completely broken down, and the compost should look like dark brown or black earth.
- Ingredients that list bio solids, which means human waste sludge. These bio solids often contain bacteria and chemicals, such as pharmaceuticals, that you do not want in your garden!
- For compost that contains animal manure, you will need to ask about the diet of the animals. Sometimes, pesticides or herbicides are used on the grass that livestock eat. These chemicals can pass through their digestive systems into manure, be used in compost, and then end up in your garden.
- Some compost will contain high salt levels. This is also something you will need to ask about.
- Some compost is mixed with ordinary soil. If you want more organic material, you will want to get pure compost, so ask about this.
When you know what to look for, you can avoid the companies that are looking to sell you junk posing as compost.
What Are The Different Types Of Compost?
Now that we know what to avoid in compost, let’s take a look at the different types of compost you might buy, including yard waste compost, composted manure, and mushroom compost.
Yard Waste Compost
Ideally, any compost made from yard waste contains a balance of both “greens” (nitrogen-rich materials) and “browns” (carbon-rich materials).
Some examples of greens from yard waste include:
- Grass clippings
- Green leaves
- Weeds from gardens
Some examples of browns from yard waste include:
- Brown leaves
- Pine needles
- Mulch or wood chips
- Wood ash
These compost raw materials are broken down over time by the bacteria in a compost pile, which thrive in moist conditions. Once it really gets going, a compost pile can get as hot as 170 degrees Fahrenheit (77 degrees Celsius)!
These temperatures will kill most pathogens (bacteria, etc.) in the compost. This means it is safe to use completely composted yard waste compost for growing vegetables.
However, one thing to remember is that many types of yard waste will contain some type of chemicals, such as pesticides or herbicides. For example:
- Grass clippings from a lawn that was treated for grubs or other pests may contain herbicides and pesticides.
- Sawdust from pressure-treated wood contains chemicals (including copper compounds), and sawdust from plywood contains formaldehyde in the glue used to hold the particles together.
Compost can also be used on top of the soil as mulch. It will help to retain soil moisture and insulate against heat in this capacity. However, it probably will not prevent weeds from growing, and it may even encourage them.
For more information on what might be included in yard waste compost, check out my article on making your own compost.
Composted manure tends to be nitrogen and carbon rich, since it is made from
- animal waste, which contains lots of nitrogen in the form of ammonia, and
- animal bedding such as straw, hay, wood shavings, or sawdust, which contains lots of carbon
It is important to remember a few things about using composted manure in your garden. First of all, the manure should be composted properly so that it is broken down completely.
This means that the entire manure pile should be turned and tended so that it all reaches the high temperatures that will kill pathogens (bacteria, etc.) in animal waste.
The manure should also be allowed to compost to prevent burning plants with excess salt or nitrogen.
For more information, check out my article on using too much manure in your garden, and my article on where you can find manure.
Finally, let’s talk about some cautions about using composted manure. First, remember that manure with too much sawdust will decompose slowly, since carbon ties up nitrogen.
This can prevent the manure from reaching temperature of 131 to 140 degrees Fahrenheit, which must be achieved for several weeks to kill pathogens such as
- E. coli
For this reason, plan to incorporate composted manure at least 120 days before harvesting any vegetables, just to be on the safe side. If the manure does not look completely broken down (you can see sawdust, wood shavings, or solid animal waste in it), don’t buy it!
Also, remember that animal waste may contain residue from herbicides used on pastures and lawns. These chemical residues can pass through animal digestive systems and end up in your composted manure.
For more information, check out this article on manure from the University of New Hampshire Extension.
Mushroom compost is ordinarily made from both yard waste and manure, but it undergoes an extra step before you buy it.
First, compost is made from animal and plant materials (manure and yard waste). The exact recipe for the compost varies, but it can contain the following:
- wheat or rye straw
- peat moss
- used horse bedding straw
- chicken manure
- cottonseed or canola meal
- grape crushings from wineries
- soybean meal
- ammonium nitrate
The compost gets up to 160 degrees Fahrenheit and is inoculated with mycelium (mushroom spawn). For 3 to 4 weeks, the compost is used as a medium for growing mushrooms.
After the mushrooms are done growing, the leftover compost is no longer suitable for growing mushrooms. However, the leftover material or “mushroom compost” still contains soluble salts and other nutrients.
Remember that this mushroom compost may contain too much salt and nutrients for seedlings and young plants. To avoid burning your young plants, mix mushroom compost with garden soil before using it for planting.
For more information, check out this article on mushroom compost from the Oregon State University Extension.
Vermicompost (Worm Castings)
Vermicompost is simply compost that is made with the help of worms (and other soil creatures). These worms help to decompose organic material by digesting it, speeding up the process of composting and making for very rich soil.
Worms can help to break down any of the compost raw materials mentioned earlier, such as yard waste (greens and browns) and manure, as well as food scraps from residential or commercial kitchens. Their waste becomes vermicompost, and can help to provide a nice boost to your garden.
For more information, check out this article on vermicomposting from the NC State Extension.
How Much Does Compost Cost?
The cost of compost varies depending on
- the type of compost you buy
- the quality of the compost you buy
- how much compost you buy at once (bulk discount)
For example, a 50 pound bag of Black Kow organic compost manure is available on the Home Depot website. At about $5.50 for a bag, this comes out to about 11 cents per pound of composted manure.
Earthworm castings, on the other hand, tend to be a bit more expensive. For example, a 6 pound bag of organic earthworm castings from OMRI through Home Depot costs about $8. This comes out to a price of about $1.33 per pound of vermicompost.
Some composted chicken manure can be quite expensive too. For example, 11.3 pounds of Charlie’s compost from Amazon costs about $20. This comes out to a price of about $1.77 per pound of composted chicken manure.
Where to Get Compost
If you want to buy bags of compost, you can find them at national retailers with garden centers, such as Walmart, Lowe’s, and Home Depot. You can also usually find bags of compost at smaller local hardware stores and garden centers.
Landscape material companies may also be able to deliver compost by the truckload and leave it on your lawn or driveway. You might also be able to pick it up from them if you have a truck.
Municipal composting sites also take yard waste from residents and allow you to take compost for residential (often not commercial) purposes.
You can also buy compost online, from retailers such as Amazon. You might even be able to find compost for sale (or for free!) on sites like craigslist.org.
Now you know that you can buy a few different types of compost online or in person. You also know what to look out for to avoid buying low-quality compost.
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