How to hot compost?

It’s a common complaint among us gardeners this time of year, and not just this time of year: We need more compost. When you’re working it into your garden soil, side dressing the plants in your borders and the transplants in your vegetable patch, even spreading it in the lawn to insure a healthy, weed-smothering and pest resistant carpet of green, well, you can go through a lot of compost rather quickly. You don’t want to skimp. But its hard not too when you have so many places in your landscape calling out for rich, organic soil amendment and only a limited amount of production capacity.

All of us organic gardeners are well-versed in the making of compost. But how effective are we when it comes to making compost. I’ve always been something of a “let-it-happen” sort of composter, putting in a minimal amount of work monitoring, turning, and adding to my piles. Patience played a big role in my composting program. I’ve used the two-bin method, a variation of the three-bin method (PDF), because I didn’t have enough room for a third bin. Leaves — my major source of composting material — that were gathered in the fall were usually ready for composting by the next fall with the addition of spring grass clippings and other green nitrogen sources. But often, they would spend another several months in the second bin before they were finished. Coming out of winter, I seldom had enough compost left from the preceding year to meet my spring needs.

At some point, I realized that I needed to be a more efficient composter, that to make more compost I had to have a quicker turnaround time and more composting capacity. That’s when I decided to get a compost tumbler. It didn’t take long to reduce my compost making time from two years to two or so months. While the quantities weren’t great — even my relatively large tumbler turned out something less than roughly 10 cubic feet of compost a couple, three times a year — the fact that I was turning out compost more frequently served to increase compost productivity.

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There was another advantage of using a tumbler. I began to pay more attention to the details of composting. To work at peak efficiency, a compost tumbler requires the perfect ratio of green and brown, nitrogen and carbon ingredients. It also requires a Goldilocks quota of moisture — not too much, not too little, but just right — and it requires frequent turning, say once a week, to keep the ingredients well-mixed and cooking. This made me start paying more attention to my compost heaps. Was I maintaining a good balance of green and brown materials? Did the piles contain enough moisture? Was I turning them as they reached peak temperature, roughly every three to five weeks during the growing season, to ensure adequate oxygen and material distribution?

Maximizing compost production requires providing ideal conditions and an adequate supply of green and brown materials. Here are some things we’ve learned from experience and have gathered from other sources that help us produce as much compost as we possibly can. No doubt, our list is incomplete and overlooks some suggestions that can help immensely. That’s where you come in. Let us know how you maximize your compost production.

  1. Make your compost heaps large enough. The bigger the bin, the more heat producing area you’ll have. Larger piles also retain moisture better. A four-x-four foot area is a good size; smaller works but this is one case where bigger is definitely better. Of course, this creates another problem . . . can you gather enough raw material to fill a large compost heap?
  2. Be creative when sourcing materials for your heaps. You’ll need much more brown, carbon material than green nitrogen material (most compost guides recommend a ration of as much as 30-to-one). Shredded brown cardboard makes a great addition (we’re not so fond of composting white paper or newspaper because of the bleach and other undesirable material they might harbor; unprinted newsprint paper is fine). Securing old bales of straw is a quick way to add brown material (hay contains weed seeds and most compost piles don’t heat up enough to prevent them from germinating once the compost is spread in your garden). Shredded sticks and pruning debris are also good as long as they are shredded. They also help create air spaces (see “aeration,” below)in the pile which speeds the decomposition process (composting require oxygen).
  3. Consider using stable wastes, coop cleanings and bedding material in your compost. The best compost I ever made was when I had a ready supply of urine-rich, manure-laced straw bedding from goat pens. If you’re lucky enough to have a source for stable straw, then you’re a blessed composter indeed. You should probably add more brown material to your heap to balance the nitrogen-rich manures in your stable straw, but the cleanings themselves, depending on how many animals you have and how much time has passed between cleanings, can be pretty close to balanced. Some caveats: horse manure will carry weed seeds that can survive the composting process; “hot” manures, like chicken and hog droppings, will need extra composting time so as not to burn your garden plants with too much nitrogen. Goat manure, mixed with straw, is perfect, neither too hot or loaded with viable weed seed.
  4. Keep your pile moist. Nothing slows down the creation of compost than a dry pile. Water the layers of ingredients as you construct the pile and keep it moist (but not too) between turnings.
  5. Aerate. Providing shredded sticks and other debris that creates air spaces in your pile will speed the process along. Crumpled paper and cardboard can also help. This is one of the reasons you turn your pile: to inject more air and help create spaces for it.
  6. Use a compost thermometer to monitor the heat of your pile. Monitoring the temperature will reveal when you’re doing everything right. It will also let you know if you’ve reached temperature hot enough to destroy weed seed (good luck!).
  7. Don’t be afraid to harvest compost early. Not every ingredient in your pile will decompose at the same rate. Shredded sticks and other dried material like wood chips and corn stalks will help your compost develop quickly by aiding aeration but may not decompose completely themselves. Don’t wait for them to finish. Use a screen to separate compost that’s crumbly and ready for the garden from these other materials. Then throw them back into the next heap.

Looking back over this list suggest one thought: all the suggestions require more attention and more work. Maybe you don’t need more compost. Lucky you. But if you do, remember: any effort applied to making compost more quickly and efficiently is worth it.

How to Speed up Your Composting

As a gardener, you likely already know about compost. Kitchen scraps, leaves, hay, grass clippings, and other organic materials, when placed in a compost bin or pile, turn into rich soil to use in your garden. Composting is a natural process. You can say it’s the most important recycling process in the ecosystem. Every living thing on the planet eventually dies and breaks down into soil to help new plant life (and, subsequently, every other living thing) flourish. We want to simulate this process on a small-scale in our backyard. Instead buying fertilizers and soil every year, compost is a great way to not only have access to a constant and free source of nutrient-rich dirt, it also helps cut down on the amount of garbage we throw into landfills.

The process can be very slow. Normally, composting material doesn’t become usable soil until the following year. I thought that was the way it was, until I found out that, under proper conditions, compost can actually be made in a month or two. The rate of decomposition has to do with microscopic bacteria and other microorganisms that live and thrive in your pile. The key is to give them everything they need to work and multiply. The more microbes you have and the more you feed them, the faster your pile will compost!

Step 1 – Have the Proper Size Pile

Compost only happens if the center of the pile is hot enough to quicken the decomposition process. To maintain this at all times, your pile needs to be at least three cubic feet, or about three feet tall by three feet wide (the size of a large garbage can). This allows heat to be retained, even on colder days. Piles larger than five cubic feet are too big, as they do not effectively allow air to reach the center.

Step 2 – Keep the Pile Moist, but Not Too Moist

Like any living animal, the microbes in your pile need water to survive. Your compost should be moist but not sopping wet, like the texture of a wrung-out sponge. Too wet and fermentation sets in, making it smell; too dry and the microbes will die. If, after a heavy rainfall, your pile is sopping wet, add dry leaves, shredded newspaper, or dry wood chips to soak up some of the water. Then, check every few days to make sure it hasn’t become too dry. If it does, just mist it down gently until you get the moisture you need.

Step 3 – Allow Oxygen to Reach All Areas of the Pile

Good microbes need oxygen to survive as well; this is why you can’t make your pile too big. A wet, oxygen-poor pile encourages anaerobic bacteria growth (microbes that do not need oxygen to survive), making your pile sour and smelly like a swamp. Actually, this is why swamps smell the way they do; a swamp is nothing more than a massive anaerobic mess of composting. This composting will be slow and slimy. You do not want this, and neither do your neighbors.

To encourage oxygen-rich, smell-free microbes, turn your pile often to aerate it. Take a pitch fork, shovel, or special compost tool and literally twist and sift the compost pile, allowing oxygen in. Turn the center of the pile out towards the sides, and turn the material on the sides into the hot center. Ideally, turn your compost once a week. If that does not produce compost as quickly as desired, turn it more often.

This is the reason compost tumblers are so effective. The action of tumbling the compost around helps aerate the materials, resulting in super-fast compost making.

Step 4 – Layer Your Compost with Green and Brown Materials

Your busy microbes need two types of food to thrive: green, nitrogen-based material for protein and brown, carbon-based material for energy. Mix these in layers for optimal effect, at a ratio of about 1/3 green material and 2/3 brown material. If you add too much green the decomposers will work too fast and use up all of the oxygen, causing the pile to smell. If you add too much brown, the pile will decompose very slowly. Green materials include kitchen scraps, coffee grounds, fresh grass clippings while brown materials are things like old leaves, wood chips, and shredded newspaper. Also, you should shred your brown materials before adding them. The smaller you can get them, the faster they will decompose. Your compost is ready to use when it is dark, earthy smelling, and crumbly.

When adding new materials, sprinkle water on them if they are not damp, and then add some extra soil from your garden to introduce more microbes already in the soil.

Follow these steps to maintain moisture and oxygen levels and your pile will heat and decompose quickly. Before you know it, you’ll have fresh compost in about a month or two! Top it up in your garden beds to introduce more nutrients or use it as mulch. There is nothing better for your garden!

If you’ve already started composting, you’ve probably got the basic idea of what goes onto the pile. You’re already dumping your peels, cores, leaves, clippings and coffee grounds. You’re already thinking about your browns and greens, gathering them from your kitchen and yard. If you want to take composting to the next level, and reduce your household waste even further, here’s a list of some less-discussed items that can also get tossed in your composting bin or tumbler.

1. Shredded newspaper
Glossy magazines don’t make for good compost, but thin printed paper can go on the pile. Help it break down faster by shredding it. According to composting guidelines from the Cornell University Waste Management Institute, most newspapers today are printed with non-toxic inks and pose no health risk.

2. Paper towels and napkins
But only if you’re cleaning up food with these items—if you’re sopping up anything that might have chemicals don’t put them in the compost to avoid any possible contamination.

3. Wine and beer
If your wine has gone vinegary or your beer has gone flat, don’t fret—just pour it onto the pile.

4. Expired spices

5. Bedding from hamsters, rabbits and guinea pigs

6. Cotton and wool fabrics

7. Jam, jellies and fruit preserves

8. Used matchsticks

9. Leftover brine or canning liquid
If you’re not using those juices to cook with, you can add them to your compost bin.

10. Jell-O (gelatin)

11. Expired yeast
You might not want to risk a bad batch of bread with a packet of yeast that’s past its expiration date. But according to the composting experts over at Gardens Alive, it may still have some microorganisms that can help your compost along.

12. Dry pet food
If that old bag of cat food is hopelessly stale, or your puppy refuses to taste a new brand of kibble, you can throw dry pet food into the compost bin.

13. Bamboo skewers

14. Wooden chopsticks
They may take a long time to biodegrade, but it will eventually happen. Consider breaking them up a bit to speed the process. Although, it’s better to hang onto reusable chopsticks, and ask for the disposable kind to be left out of your take-out order.

15. Wood ash

16. Tea bags

17. Candy

18. Hair
Yours or your pet’s.

19. Feathers

20. Nail clippings
Your pet’s or your own, as long as they’re polish-free.

21. Cotton balls

22. Tooth picks

23. Natural wine corks

24. Saw dust

25. Eggshells
I have seen several articles that recommend against composting egg shells, but I don’t know why. Eggshells will break down in most compost systems. According to “Compost City” by Rebecca Louie (a great guide for beginners), you can even add them to worm bins.

Do you have any other uncommon additions to the list of compostables? Tell us in the comments!

This updated article was originally published in 2015.

Advice for the Home Gardener from the Help Desk of the
UC Master Gardener of Contra Costa County
garden compost pile Client’s Request: I’m trying to implement an ongoing compost pile to sustain my backyard vegetable garden. However, my compost pile isn’t getting hot. Would you please tell me why and what I can do to maintain a “hot” compost file.
Help Desk Response: Thank you for contacting the UC Master Gardener Program Help Desk with your question about compost.
You said that your compost bin is not getting hot. If the compost pile is not heating up, then the pile is too wet or too dry or there is not enough green material (or nitrogen) present. If too wet, the material should be spread out to dry. If too dry, add moisture to make it “spongy”. If neither of these, then the nitrogen is low and this can be corrected by adding materials high in nitrogen (lawn cuttings, etc.).
You asked whether you can place materials which are not fully composted into the garden bed. My comment was that yes this is possible, but that it will draw nitrogen from the soil to continue the composting process in the garden bed. Also, heat is the driving force to kill funguses or other living material in the pile prior to placing it in the vegetable bed.
We discussed making sure there is enough nitrogen present in the composting contents. The document linked below on rapid composting discusses this –

And here is a link on composting basics that you might also find informative:

Free Recycle Smart Compost Class: You might also be interested in the compost class offered by Recycle Smart. The class is free, and was developed to help residents understand the importance of organics recycling, build composting systems, recycle food and yard waste at their homes, build healthy urban soils and support thriving landscapes. For APPLICATION, dates and more information visit www.RecycleSmart.org/CompostSmart. The application deadline for the next class is February 22, 2019.
Good luck on your compost. Please do not hesitate to contact the Help Desk if you have more questions.
Help Desk of the UC Master Gardener Program of Contra Costa County (MCW)

Winter Composting: Retaining the Heat When the Temperatures Drop

There are a few primary elements necessary for organic materials to break down and become compost, the “magic ingredient” in so many successful gardens. Basically, you must provide the minimal conditions for the microbes which fuel the process to survive. They need air circulation, moisture, warmth, and a ready supply of organic materials, comprised of a balance of nitrogen-rich greens and carbon-rich browns. In the winter, the most difficult element to provide is warmth. Let’s take a moment and consider some possibilities for shielding your compost from the frigid temperatures you may encounter, depending on your growing zone.
Two common schools of composting are often called “cold” composting, and “hot” composting. Cold composting requires a laissez-faire approach. It will work with any basic compost bin or pile, and it generally involves only adding your materials as you gather them. All organic material will, eventually, break down into compost, with very little interference from humans. If you are very patient, have limited time, or just no inclination to play around in rotting food-stuffs, this is the method for you. Cold composters are not much concerned with the effects of winter on their compost, as they are not trying to maintain high temperatures in the middle of their bins in the first place.

Hot composting is the more labor-intensive method, as it requires more attention to getting the balance of nitrogen to carbon ingredients right, with a ratio of 1:20 to 1:40 being the ideal, and usually involves some method of mixing the ingredients periodically. Compost tumblers would fall into this category, with their emphasis on turning the drum to re-distribute the ingredients every time you add more, as would any bin or method that required you to turn or mix the compost frequently. The advantage is that the compost progresses from “rough” to “finished” much more rapidly. It is the hot composters that dread the coming of sub-zero temperatures, as it basically brings the active process of composting to a halt. The materials will continue to deteriorate (as anyone who has left a carved pumpkin out in freezing temperatures can attest), but the bacterial process is seriously slowed by the cold temperatures.
As winter approaches, I would encourage either type of composting gardener to begin hoarding organic material. Leaves are available in great supply in the autumn, and you may find that your neighbors have very kindly collected and bagged them up for convenient removal. This presents you with two options: you can ask if you can have their bags of leaves, and take this opportunity to education them about the wonders of composting, or you can go into stealth mode, and snatch bags from the curb whenever the opportunity presents itself. I don’t think there is much inherent risk in that, as I can’t imagine anyone chasing you down to recover their bagged leaves.
Rather than adding all of your collected leaves at once, I advise storing them near your compost bin, so you can periodically add layers to your bin. During the summer months, I use a large plastic trash can with holes drilled 6 inches up the sides to grow potatoes. I repurpose that can during the winter months by filling it will mulched leaves and setting it beside my bin. I set a large brick on the lid to discourage it from blowing around my yard and redistributing the leaves over my lawn. My parents are blessed with a row of beautiful maple trees along their house, and they provide me with 8-10 large bags full of mulched leaves each year, as well. I store those in our shed until needed. After your first freeze, add a good 10-12 inch thick layer of leaves on top of your compost, to hold in the heat. It is easy to dig a little hole in the center and empty a countertop compost bucket into the leaves and recover them.
This is also a good time to reclaim straw that you may have spread elsewhere in your garden as mulch, perhaps in your strawberry patch or between your tomatoes. Of course, if you leave it in place, it will eventually break down and enrich the soil, but the more likely result will be that it will freeze and still be there in the spring, when you want to replant. Additionally, leaving leaves and decaying straw in your berry patch may encourage fungus to attack your plants. If you rake it up and add it to your compost, it will have a double effect: it will add to the carbon end of the balance, and it will provide lots of air pockets in the compost. I intentionally leave a few larger sticks and stems spread throughout my compost in the colder months, because I know that realistically, I will not head out there with a pitchfork and turn the stuff in subzero weather. Providing some air pockets throughout will help your beneficial microbes survive. Adding loosely wadded newspaper or cardboard paper towel tubes will have the same effect, creating air spaces within your compost.

You may also wish to add a second kitchen scrap collection bucket to your counter, or store them in a covered bucket under the sink. Again, I know myself, and my trips to the compost bin become less and less frequent as the temperatures drop. If I could, I would curl up and hibernate through the winter months. Reducing your trips to the compost bin can actually be a good thing, as you lose a little heat every time you open the lid. Despite your summertime commitment to regularly turning your compost, you want to leave it as undisturbed as possible during the winter, to avoid losing what heat you have managed to retain!

The true key to winter composting, however, lies in one word: insulation. If you are a dedicated composter, you may already own a compost thermometer, and have experienced the wonder of plunging the probe into the center of your pile to find the interior happily cooking away. As you most likely know, keeping it at a warm interior temperature speeds up the process, yielding compost more quickly. In the winter, however, it becomes much more difficult to maintain that inner temperature. If your pile or bin freezes solid throughout, your microbes are either dead, or hibernating until warmer temperatures return. Here are some ideas I’ve come across for shielding your bin from the cold.

First, consider your location. Ideally, your compost will be located in an area that is easily accessible from the house, so you don’t have to shovel a long path to reach it. Mine is just outside my back door, around the corner. Second, if possible, put it in a shielded location, where the wind is not too intense. My location isn’t strong on this point, as it is on the northeast corner of my house, but I didn’t have much alternative. Thirdly, and probably most importantly, locate your bin where it will receive direct sunlight. Your compost is going to need all the solar help it can get! Covering it with a plastic tarp, preferably a dark colored one, will retain moisture and heat in your bin or pile.

One of the simplest methods of insulating your compost bins from the cold wind is to stack straw bales around the sides of your bin. Straw bales are not difficult to find in the autumn, and are often sold for $3-5 a bale in my area. Straw is a great insulator, but allows air and moisture to circulate. I even read of someone abandoning their tumbler during the winter months, and instead building a square enclosure of straw to house their composting ingredients. If you would like to read about an interesting use for those bales of straw in the spring, visit our Strawbale Gardening forum here on Dave’s Garden. If you are already a strawbale gardener, put those bales to work in the winter months, when they would otherwise sit idle!

Alternately, if you have an abundance of leaves and a mulching lawn mower, you can collect the mulched leaves in bags, and strap or tie them around the outside of your bin. You can use the brown paper lawn waste bags, which are themselves compostable, if you have dry winters. If you tend to get lots of snow or rain in the winter months, you may have a mess on your hands if the paper bags dissolve. Instead, consider putting the leaves in black plastic trash bags and packing them around the bin, securing them with ties or weights to prevent them from blowing around in a stiff wind. The black plastic has the added bonus of collecting solar energy. Just be sure to recycle or reuse them in the spring, as you use up their contents for mulch or compost.
If you have a loose pile for composting, you may need to concentrate your pile into a more compact form to help retain the heat. This would be another case in which a frame of straw bales might be advisable. Another option would be to cover your pile with a tarp or piece of heavy plastic. If you can find a dark-colored tarp, to absorb any solar energy on those rare sunny winter days, all the better! Just don’t seal the pile off too tightly, as your microbes need air to live.

If you have bins made of wood, pallets, or chicken wire stretched around corner posts, you have more options. Line the inside walls of your empty bin with cardboard, then add a second wall of cardboard inside the first. Leave a space between them, and fill it with insulating material, such as straw, mulched leaves, or even crumpled plastic shopping bags. You may then fill the space in the center with your organic materials. The cardboard is compostable the following spring, counting toward your carbon ratio, assuming it is not laminated. This does reduce the size of your usable space, but if it provides the necessary conditions for your compost to “cook,” it is a sacrifice worth making. Better to have a smaller bin that is actively breaking down your waste than a large, sprawling one that freezes solid and has to start over in the spring!

If you live in a colder growing zone, Mother Nature herself may provide you with a great insulator: snow! Survival classes will teach you to dig a cave down into the snow if trapped in a blizzard, allowing your body to retain its heat. Snow can have the same effect on your compost bin, if you pile it thickly around the sides and even over the top. Wouldn’t it be fun to dig out the lid of your compost bin, lift the hatch, and see steam rising from your compost when you dig past the top insulating layer? If you have a two-bin method, one for nearly finished compost, and one for adding new materials, this would be an ideal method for the almost-finished bin that doesn’t have to be accessible. It also provides needed moisture when warmer temperatures return and the snow melts around your bin.

If you are partial to digging holes, as some gardeners are, you can even use the ground itself to insulate your compost. If you have access to a large plastic garbage can, you can partially bury it 6-12″ into the ground. Drill large air holes 6-12″ inches from the top, and stack straw bales around the exposed portion of the sides, being careful not to block the air holes. You can also fill any spaces between the bales and the can with soil, leaves, straw, or other insulating material. Keep the top on, to discourage roving critters from feasting on your kitchen scraps, and you have a winter compost bin!

Regardless of the preparations you make, barring the ability to provide some sort of heat source, your compost bin will progress more slowly in the winter. If you have an extended period of extreme cold, your materials may freeze through in spite of the efforts you made to prevent it. If that happens, don’t despair. In the spring, stir up your compost, add moisture if needed, and add a new batch of organic materials, along with a couple of shovelfuls of soil from your garden. The combination of air, moisture, food, and organisms will get to work and restart the process.

For more information about composting, visit the Soil and Composting forum here on Dave’s Garden. The “sticky” at the top of the forum is a great place to begin learning about the basics of composting!

Also, browse through these previous articles written on the subject.

Back to Basics Composting, by Kathy LaLiberte

Composting, On the Not-So-Grand Scale, by Sally G. Miller

Countertop Compostables Containers, by Sally G. Miller

Household Composting, by Tamara Galbraith

Low Cost Compost for All, by Caleb Garvin

There are many more articles on composting available here on Dave’s Garden. To find them, click on the tag “soil and compost” in the Helpful Links box at the bottom of this page. Alternately, click on the Guides and Information tab at the top of your homepage, scroll down to Articles (the seventh category down), and enter “compost” in the search box. There is a wealth of information available on Dave’s Garden, if you only know how to find it!

Special thanks go out to Daves’ Garden member Bev Walker, for her picture of her compost tumbler and bin. The first image, at the top of the article, is from Flickr Commons, and is attributed to net_efekt. All other images are from Flickr Commons; the photographer may be found by hovering your cursor over the picture.

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PHOTO: iStock/Thinkstock by J. Keeler Johnson May 31, 2016

Compost bins are a great way to create quality, organic soil perfect for gardening. By placing organic items inside and letting them naturally deteriorate into soil, you are turning waste and garbage into a usable, valuable product—what could be better than that? Of course, you can’t throw just anything and everything into your compost bin and expect it to quickly deteriorate. Some items will need to be broken down manually first in order to speed up their decomposition. Here’s what you need to know for fast composting.

There are several general rules that aid in fast composting. Adding an equal amount of “green” or fresh items like grass clippings with “brown” or dried items like dead leaves, which provide both nitrogen and carbon to the microorganisms that are doing the decomposing. (See a basic guide to brown and green items in the infographic below.) It can also speed things up if you turn the compost pile inside out every few weeks so that the outer edges of the pile get some time in the middle. But even when following these rules, there are still some items that need a little more attention before you toss them into your compost bin.

(To download image, right-click or Ctrl-click and choose “Save Image As.”)

Oak Leaves

Leaves of all sorts are a great material to add to your compost bin, though they might need a bit of preparation for fast composting. In general, dried leaves should be shredded before you add them to your compost bin, and this goes double for oak leaves. Because they contain tannin, they resist decomposition much better than other types of leaves; shredding them thoroughly can help speed up the process.

Fruit & Vegetable Remains

Because of their size, produce scraps such as apple cores, peach pits and corn husks can be slow to break down, so chopping them up into small pieces will help aid fast composting. The U.S. Environmental Protection Agency recommends burying fruit and vegetable scraps beneath 10 inches of compost for better results. If you have a lot of fruit and vegetable scraps, you can consider adding worms to your compost bin—they’re great at decomposing food products!—or create a special worm composting bin specifically for fruit and vegetables.

Woody Branches & Twigs

Not surprisingly, woody branches or twigs take some time to decompose. Anyone who has ever left a fallen tree to rot knows that the process can take years, even decades. And while you won’t add entire trees to your compost bin, any small branches you might add will need some extra attention in order to accommodate fast composting. Rather than adding them to your bin in one piece, be sure to chop and saw them up into lots of small pieces. In addition, try not to add any large-diameter branches to your compost bin. Small twigs are fine, but anything thicker than a few tenths of an inch or so might take too long to decompose.

Eggshells

Although most animal products, such as meat or dairy, should generally be excluded from compost bins, eggshells are one exception. They can be a valuable source of calcium, but are very slow to decompose, sometimes remaining visible even after the rest of the items in the bin have turned to compost. To help them decompose better, let them dry for several days and then crush them thoroughly into small pieces, which are better-suited to rapid decomposition.

By keeping these tips in mind, you’ll soon be well on your way to creating top-quality compost in rapid fashion.

Hot tips for getting your compost pile cooking

Q. Dear Umbra,

I’m tired of my compost not cooking. Can I just bury it around my plants and pull the stray volunteer seedling that emerges?

Kristina
Cleveland, Ohio

A. Dearest Kristina,

I’m hearing some frustration from you here. Perhaps also disappointment, annoyance, resentment, even a twinge of perturbedness — enough to make you want to throw in the towel on this whole composting enterprise. I understand, and what’s more, assure you that you’re not alone. Composting sometimes requires trial and error before you get the hang of it, and you’re not the first to think about digging a pit out back and burying the whole uncooked mess.

So, could you simply disappear your as-yet-uncomposted pile around your gladiolas, gangland-style? Well, yes (and more on that below). But Kristina, I urge you not to give up on your compost just yet. I’ll bet that one of only a few problems is to blame for its poky transformation from scraps into garden gold, and a few simple fixes can get things back on track. So let’s pull out the pitchfork and dig in.

A compost pile needs three basic things to produce rich compost: heat, water, and oxygen. The aerobic bacteria (that is, the ones that need oxygen) do much of the dirty work of breaking down your scraps, and they need adequate airflow to function; without proper working conditions, they essentially go on strike, and anaerobic bacteria take over. These anaerobic microorganisms still get the job done, but much more slowly, and they produce methane to boot — so it’s better to keep the aerobic bugs happy. Water is also important: too much and that airflow gets suffocated, too little and the bacteria can’t survive. The pile’s heat depends on this oxygen and moisture, and also on the mix of ingredients and size. I’m guessing we’re dealing with an imbalance to at least one of these big three elements in your compost pile, Kristina.

To figure out which one, head out back and give the pile a good look. Poke around with a stick or shovel; grab a handful and squeeze; dig into the middle of the heap. What do you see and feel?

It’s too wet: If you discover slimy layers, and/or you can squeeze more than a few drops of water from a handful, you’re probably running short on oxygen. To fix this, get in there with a shovel or pitchfork and give the pile a good turning over, fluffing it up as you go, to aerate it. Consider adding some more dry materials, such as crispy leaves, shredded corncobs, or straw; tossing in twiggy ingredients will also help maintain space for better airflow. Continue turning the pile every couple of weeks to make sure oxygen is really getting in there. Ideally, the pile should feel like a damp sponge. You might also want to add a tarp or other cover to protect it from the elements, or the next cold November rain could make all your work for naught (as well as make you nostalgic for the era of bandana headbands).

It’s too dry: On the other hand, if your pile is all dry, woody material or crumbly stuff, you’ll also need to grab that pitchfork and get turnin’. But this time, enlist a sprinkler or drip hose to add some much-needed water to the mix. Throwing in more wet materials, such as kitchen scraps or yard clippings, will also help.

The balance is off: Maybe it’s not only the moisture content. Could it be your mix of “greens” (high-nitrogen items) and “browns” (high-carbon items) in the pile? You want to keep these elements in the proper ratio for optimal composting; head over here for more on how to pull that off. Backyard piles are often short on those nitrogen-y greens, so adding food scraps, alfalfa pellets, blood meal, or chicken manure can kick-start the action. It’s also helpful to chop or shred materials more finely, especially additions like eggshells or brush trimmings, for quicker decomposition. Have at it with a shovel or machete, or run over materials with your lawnmower.

It’s just too small: Here’s an easy one — compost piles need to be about three cubic feet in size to hit those higher temperatures you’re looking for. Is yours undersized? Collect more ingredients to get things cooking.

Or maybe your level of discontent with your compost pile is so great, you don’t have the wherewithal for all this troubleshooting. This brings us back to your original question: Can you just bury all this stuff? You can indeed: This is its own form of composting, in fact, called pit composting. Just dig a 12-inch-deep hole and fill it with your organic trash (just no dairy, meat, or pet poop, a rule that applies to regular compost piles, too). Repeat as necessary, and the soil microbes will do their thing. If you’d like to get a little fancier about it, you might also try trench composting, where you bury the scraps between rows of your garden for added fertilizer next season.

As it happens, now is a great time for a compost makeover. Decomposition will slow or stop during the coldest months, but your newly refurbished pile will be ready for a fresh start come spring. Think of it this way: You’ll be way ahead on your New Year’s resolutions this year.

Subterraneanly,
Umbra

What is the difference between hot and cold composting?

Everyone seems to have got the idea that compost must become hot. Any organic material will rot down into compost. It doesn’t necessarily have to get hot. So, if you are looking at your compost pile and it looks and feels cold, this isn’t a problem. Don’t allow the fact that your compost isn’t getting hotter, affect your day.

Adding carbon will make compost hotter

If you’re convinced that your compost must be hotter than it is, then, you may find that you need to add more carbon based materials to the compost that you have. Carbon is an energy element. It will be in cardboard, paper and generally woody materials. The adding of this to any compost will be the best you can do to make your compost become hotter.

If your compost pile is made up of mainly woody material, it may be that it’s too dry. Dry grass won’t rot. The simple addition of water will change this. You won’t need to add much. Organic materials only need to be moist for the composting process to begin.

You may find that a dormant heap of dry, organic material will become significantly hotter after adding enough water to make it damp.

Some will tell you that you need to build your compost pile with the specific aim of producing heat and that you need to monitor the temperature and somehow control the heat to prevent overheating.

A compost pile made up of the right proportions of ‘greens’, ‘browns’ and sufficient moisture, will become hotter without any intervention from anyone. The compost will do its own thing.

You may be tempted to dig over the heap in an attempt to help the compost become hotter than it is but if there is evidence that heat is being generated, the best thing that you can do is to leave it alone.

Don’t dig compost in the hot phase

Digging over a compost heap while it’s going through the hot phase, will risk cooling of the compost mass. If you see steam rising from your compost, leave it for a couple of weeks, or possibly longer if you have a big compost pile.

A compost pile that’s become hot, will remain hot if the compost mass isn’t disturbed. The fibrous nature of compost can be very insulating which means that the heat that’s generated can’t easily escape. The heat will build up. This is the main reason why a compost pile becomes hotter.

There are suggestions that the heat generated in a compost pile could be collected and used for domestic heating. This could be practical if the compost pile is large enough. A small compost pile may become hot and generated a considerable amount of heat. It may be quite noticeable if clouds of steam are being generated, especially if it’s a heap of lawn clippings.

If you have ambitions of extracting heat from a compost pile, you need to be aware that the heat from a compost pile will only last for a short while. The structures required to collect the heat will only be in use for a short while.

You may want to make compost that becomes hotter but high temperatures will inevitably kill some of the microorganisms that are needed for breaking down organic material. Should you worry about this? No. In the right conditions where heat can be generated from compost, the mass will get hotter and hotter until the temperature reaches the maximum potential.
When the energy source within the mass has been exhausted, the mass that’s generated heat will start to cool. The heated heap will continue to make compost. Any microorganisms that will have succumbed as the compost mass became hotter, will re establish a place in the cooling compost, having survived in parts of the compost where it didn’t become hotter to the point where they couldn’t survive.

What is the difference between hot and cold composting?

The only difference between hot and cold composting is the speed. When the conditions are right in a compost heap, pile or bin the temperature goes up and we get hot composting. Any organic material in a hot composting pile will break down much faster.

The speed will only apply in the early stages of the composting process.

The heat will only last for a short while. The length of time that compost will remain hot depends on the size of the heap. It will cool down and revert to a cold rot to continue to the end conclusion.

Both hot and cold composting will deliver usable compost.You will often have little choice over how your composting system works. It will depend on the ingredients and volumes of materials involved.

It’s largely pointless concerning yourself over what the difference is between hot and cold composting. Making compost from organic material will happen one way or another. Hot or cold composting will be irrelevant when you come to dig out the finished product.

You won’t notice any difference in compost that has been generated from either hot or cold composting.

There are plenty of arguments being put forward that insist that you must aim for a hot composting system. The heat generated in hot composting will kill weed seeds but unless you have the compost in a closed vessel that comprehensively heats the entire mass to the required temperature, it won’t get all of them.

The same applies to the claim that hot composting will sanitise the compost that you’re making. If the composting heat can be held at a temperature of 60degs C for long enough, this will kill potentially harmful pathogens. As with the weed seeds, if the entire mass isn’t heated to the required level, then there will be pockets where things can survive.

Hot composting will kill pathogens where the compost is hot enough. Cold composting need not be a problem when considering pathogens. Cold compost is much more attractive to worms. Worms don’t like it hot. Worms will consume pathogens and render them useless. In cold compost, worms will cover every part and digest everything at least once.

The general advice is to dig over a hot compost pile and aim to place the outer cold parts in the middle of the repositioned pile. This is intended to expose the cold regions of a compost pile to the heat that’s generated in the middle of a pile. This may work and the cold parts may become hot enough to sterilize it.

Relying on the heat from hot composting in a domestic setup would be risky. It’s worth noting that when you dig over a hot or heating compost pile, that the digging action will allow heat to escape and the pile, as a whole, will cool down. This would then take the pile from being hot compost to cold compost.

Cold composting provides an opportunity for every seed to survive and germinate. The thing about cold composting is that you can know that this will happen and be ready for it. Very often rogue seeds will germinate in cold compost. Because of the high level of nutrients in compost, hot or cold, these seeds will grow quickly and clearly present themselves.

The plants that grow from these seeds will be tall and vulnerable. They can easily be broken off. In a tumbler composter e.g. the Rolypig compost tumbler, seeds will germinate into small plants that will become broken and crushed when the barrel is rolled over.

The Rolypig is a cold composting system. It’s better if weed seeds do germinate inside a cold-compost tumbler because the rolling action will get rid of them. It’s just another way of ‘sterilizing’ the compost of any rogue seeds.

Some people have doubts about putting plants in with the compost that have been treated with herbicides. The worry appears to be that there may be residues that survive the composting journey. There is data that shows that these residues will break down completely during the composting process. There is a claim that herbicide residues will break down more than 30 times faster during hot composting compared to cold composting.

It needs to be understood that this rate of break-down will only happen when hot composting is actually happening. This period of time may vary according to varying factors that will influence the overall composting process.

The quantities of herbicide that are likely to find their way into compost via treated plants, is likely to be very low and will break down over the prolonged time-span, regardless of whether you insist on hot composting or settle for cold composting.

The initial rate of decomposition will be much higher if hot composting is encouraged to take place.

The heat from hot composting will kill insect larvae and fly-eggs. So there should be a reduction of maggots in the main part of compost where enough heat is generated. There may be some that survive if they can find an area where there is little or no heat.

After the heating phase has passed, there will be little or no food value in the parts of compost that have been heated, to attract egg-laying insects.

The opposite will be happening where there is cold composting. The organic material will rot very slowly in the early stages and throughout the cold composting process. This will provide plenty of opportunities for insects to lay their eggs and maggots to take up residents.

Cold composting doesn’t need to be a problem as regards flies and maggots. The regular adding of hydrated white lime will deter flies and other pests of a rodent nature. The lime will also accelerate the composting process almost to the point where it could compete with hot composting in the early stages.

Then we have the question of smells. Some will say that cold composting will generate more of a smell than hot composting. Both can perform admirably when it comes to smell. Hot composting will always have the edge over cold because water is driven off as vapour.

Water vapour will become airborne and have the potential to reach more noses. This will continue until the heat level drops. After this point the pile will revert to a cold composting mode.

Cold composting will generate some water vapour. In a small, domestic composting system there’s rarely enough of a mass of organic material to generate enough heat to display noticeable quantities of water vapour.

The heat from hot composting is often seen as a convenient way of driving off excess water, thus allowing a more efficient decomposition there after. This is true. A compost pile that’s too wet will be self sealed. Air won’t be able to get in so easily but, unless the composting container is completely sealed, excess water will drain away.

Air will find its way into any composting mass, hot or cold. All organic material will convert into compost. Whether hot or cold there will be no difference in the final outcome, it will all get there in the end. It’s just a matter of which way it will happen.

Tell your friends about the Rolypig composter

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Want to get finished compost faster? You may want to try increasing the internal temperature of your backyard bin! Contrary to popular belief, compost piles do not heat up due to atmospheric conditions (i.e. sun exposure or warm weather) but rather, as a result of heat generation by specialized bacterial populations. Increased bacterial population density means faster decomposition due to more rapid consumption of nitrogen, carbon, moisture, and oxygen. This intensive resource consumption correlates to rapid fluctuations in bacterial population size and variety. This means that a pile is only hot for a finite period of time: temperature spikes will rarely last for more than a week, and peak temperatures are unlikely to be sustained for more than a few days. Many composters will try and achieve multiple temperature spikes over several months, helping to neutralize any pernicious weed seeds amongst the pile, and producing finished compost in a shorter period of time.

While by no means an exhaustive explanation of the hot composting process, the following are some tips to experiment with creating some heat in your backyard bin!

(1) INCREASE VOLUME: The greater the volume of materials (i.e. the more space and resources for bacteria to colonize and consume) the more likely the pile is to generate heat. Filling a bin full of material at the start or topping off a pre-existing pile will do the trick. Increasing the volume of compostables naturally increases the size of the pile core, where temperatures will be the hottest. NOTE: It is possible to produce hot compost in small volumes, but requires a greater dedication to creating an optimal balance of inputs (i.e. calculating individual C:N ratios) and to habitual and responsive pile monitoring (i.e. ensuring consistent, even moisture content).

(2) INCREASE NITROGEN: Adding nitrogen-rich ingredients like coffee provides “protein” for the bacterial communities, and will activate speedier decomposition processes in the bin. If adding a blast of nitrogen, aim to turn your compost to distribute the resource more evenly throughout the pile.

(3) MAINTAIN MOISTURE: Monitoring moisture levels to ensure even dampness is a surefire way to speed up decomposition (ideally, moisture content throughout the pile should be comparable to a wrung-out sponge). Other tips to retain moisture in the pile include keeping your bin in a shady location (slows dehydration from sun exposure) and keeping a layer of browns (i.e. burlap, pine needles) on the top of the pile.

(4) STRATEGIC AERATION: It is important to keep your pile aerated to provide enough resources for bacteria to thrive; however, turning too frequently can cause the pile to dry out. Timing turning with falling internal temperatures will re-generate heat in the pile, so responsive aeration is the best strategy to keep a pile consistently hot. Turning about once a week is a good rule of thumb.

(5) WATCH YOUR THERMOMETER: When it comes to composting, “the hotter the better” does not always apply. A pile is considered ‘hot’ when it reaches between 130°F -140°F. Beyond 150°F, beneficial bacteria will begin to die off in large numbers, and efficient decomposition may be compromised. In order to determine if you are successfully generating heat, dig into the core of the pile to check for warmth (you might even see some steam). If you are interested in quantitatively monitoring internal temperature spikes, purchase a long-stemmed compost thermometer. Studying changes in the pile can be lots of fun, and many composters know off-hand their “personal best” temperatures!

Wishing you all good luck and speedy decomposition!

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