What you can and cannot compost

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Things you can compost!

Materials Carbon or Nitrogen Details
Alfalfa meal and hay  Carbon Shredding or chopping it up will help it break down quicker
Algae, seaweed and lake moss
 Nitrogen
Good source of nutrients and minerals.
Apple pomace (cider press waste)  Nitrogen If dried use as a carbon
Ashes (wood, not coal)
 Neutral
Use only wood ashes since coal ashes can be toxic to plants. Use sparingly as a pest deterant.
Banana peels Nitrogen Shredding or chopping it up will help it break down quicker
Beverages, kitchen rinse water
 Neutral
Help keep the pile moist, but don’t over do it.
Buckwheat straw or hulls  Carbon Shredding or chopping it up will help it break down quicker
Cardboard
 Carbon
If you have lots of this, consider recycling it. Otherwise, shred into small pieces in pile.
Cat litter (unused!)  Carbon Ugh..make sure its unused
Clover  Nitrogen Add it for a bit of luck!
Cocoa hulls  Carbon Shredding or chopping it up will help it break down quicker
Coffee grounds (and filters)
 Nitrogen
Great source of nitrogen and worms love coffee grounds! The filter will break down so add it too!
Cornstalks, corn cobs  Carbon A little tricky, so shred and/or break down and mix well into pile.
Cotton Bur  Nitrogen Great to use to jump start your pile or warm it up
Cowpeas  Nitrogen Add them if you got them!
Dog food
 Nitrogen
Best if not a meat based dog food
Dryer lint
 Carbon
Yum, lint. Make sure you moisten it a little before you add it.
Eelgrass  Nitrogen If dry use as a carbon
Egg shells
 Neutral
These break down slowly, so make sure to crush these before adding.
Feathers
 Nitrogen
Slow to break down, shred if possible to speed up process
Flowers  Nitrogen Green use as Nitrogen, dried use as carbon
Fruit peels (not limes)  Nitrogen Best if you cut them up to small pieces
Grape pomace (winery waste)  Carbon When dried and shredded best used as a carbon
Green Grass clippings
 Nitrogen
When green can be used as a Nitrogen
Dried Grass clippings
 Carbon
Make sure they are not too wet and mix with dry leaves for best results.
Hair
 Nitrogen
Good source of nitrogen. Make sure you scatter, so it doesn’t clump.
Hay
 Nitrogen
The best kind is hay that is not suitable for livestock and is starting to decay on its own. Make sure it is dry and weathered.
Hedge Clippings  Carbon Shredding or chopping it up will help it break down quicker
Hops (brewery waste)  Carbon When dried and shredded best used as a carbon
Kelp (seaweed)  Carbon Good source of potassium (perfect for growing potatoes!). Use sparingly or sprinkle kelp meal in to get your pile cooking.
Leather (leather waste)
 Nitrogen
Shredding or chopping it up will help it break down quicker
Leaves
  Carbon
Shredding or chopping it up will help it break down quicker
Manure from herbivores (cow, horse, pig, sheep, chicken, rabbit)
 Nitrogen
Best if known to come from a herbivore
Newspaper
 Carbon
Shredding or chopping will help it break down quicker
Nut shells  Carbon Shredding or chopping will help it break down quicker
Oak leaves
 Carbon
Shredding or chopping will help it break down quicker
Oat straw  Carbon Shredding or chopping will help it break down quicker
Sawdust and wood shavings
 Carbon
Preferably not from kiln-dried wood
Paper  Carbon Shredding will help it break down quicker
Peanut hulls  Carbon Shredding or chopping will help it break down quicker
Peat moss  Carbon Also great to add to your garden soil
Pine needles and cones
 Carbon
Shredding or chopping will help it break down quicker
Tea leaves  Carbon Best if shredded to help it break down quicker
Vegetable peels and scraps  Nitrogen Kitchen scraps are a great source of nitrogen
Vetch  Carbon From the pea family, yup add it too
Weeds
 Carbon
Don’t add if your concerned about spreading the seeds
Wheat straw  Carbon Best if shredded to help it break down quicker

 

Things you should NOT compost!

Materials
Carbon or Nitrogen
Details
Ashes (coal or charcoal)
n/a
May contain materials that are toxic to plants.
Cat droppings/litter
n/a
These may contain disease organisms and should always be avoided for composting.
Colored paper
Dog droppings
n/a
Same as cats.
Lime
n/a
High alkaline pH can kill composting action.
Meat, fat, grease, oils, bones
n/a
Do not break down, can coat materials and “preserve” them, can attract pests.
Nonbiodegradable materials
Toxic materials

 

Things that MAY be composted, but only with caution and skill

Materials C/N Details
Bird droppings
Nitrogen
Some bird droppings may contain disease or weed seeds
Diseased Plants
Nitrogen
Make sure your pile gets to at least 135 degrees Fahrenheit for a few days to let it “therma kill” the disease
Milk, yogurt, cheese
Neutral
May attract pests, so put it in the middle to deep into the pile
Weeds
Nitrogen
For best results, dry them out until crunchy, then add them to your compost pile
Sod
Nitrogen
Like diseased plants, make sure your pile gets hot enough to make sure the grass doesn’t keep growing in your pile.

{ 230 comments… read them below or add one }

Jessica February 27, 2012 at 7:07 pm

Hi! I am preparing to do raised bed gardening for the first time ever. I have very little experience with gardening. I want to do a compost pile, but I guess I need to know some things first… I had been collecting all organic fruit and veggie scraps from my kitchen in a big bowl, well, I haven’t established anything to start the actual compost in outdoors, so I set my bowl out on the deck, meantime a critter has been getting into the kitchen scraps on my deck, should I still use the scraps that have been gotten into in a compost pile? Or are they not safe because of what kind of critter it could be??? Also, I had my husband rake a bunch of leaves up out of our yard for me and there were piles that were already decomposing in our yard, I had him dump some of the more wet decomposed leaves into a garden box to start a compost, is that a good thing to do? Or do I not want to use the slimy wet decomposed leaves? Can I just start an opened compost pile like that? By just using leaves and throwing in my kitchen scraps? I also want to know how soon I can use my compost mixture into my gardening, I was hoping to use it this spring when I’m planting? Can I use it that soon or do I have to wait longer? Thanks!

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Steve March 6, 2012 at 8:54 am

@Jessica, As mentioned on your other post, yes, the scraps are still good, you need to put them in a sealed container or the critters will keep getting into them. No, I would not start my compost pile where I plan to start my garden unless I think it will be done before I plan to plant. I suggest making a pile on the side, make sure you turn it once a week, keep it moist and a balance of 70% browns and 30% greens. I doubt it will be ready by spring though.

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Sharon February 29, 2012 at 9:34 am

Also, what kinds of liquids can I add to the garden/compost besides water and “compost tea” for instance is 100% fruit/vegetable juice ok?

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Steve March 6, 2012 at 8:31 am

@Sharon, Adding a minimal amount of liquids like fruit/veggie juice will not harm your compost pile, however I would not get carried away, the acid may kill some of the micro organism which break down the material.

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Lisa March 20, 2012 at 8:38 pm

Hi! I am not quite ready to compost yet, but would like to save some of our scraps (fruit and veggie peels). Is it okay to freeze these scraps and then add them to the pile when we are ready?

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Steve March 23, 2012 at 9:48 am

@Lisa, Yes, you can freeze your kitchen scraps until its time to put them out in your compost bin.

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frik van der linden March 21, 2012 at 2:47 am

specifically, can fish be safely added to compost heaps.

Many thanks

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Steve March 23, 2012 at 9:47 am

@frik van der linden, Yes, you can compost fish, however its likely you will attract other animals so most people don’t. Also, your compost needs to get fairly hot, around 120 to 140 degrees to break down the bones, and it will take longer than normal.

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mark May 16, 2012 at 10:58 am

A quick zap in the blender or food processer will help a ton when composting fish material, and adding some fish “juice” to your compost bin or pile will add a ton of benefit. Just dont go overboard too much

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Rick March 26, 2012 at 4:14 pm

I have a compost bin from an unused container. It’s white, I’ve noticed that some compost bins at the stores are black or green. Should I spray paint my container?

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Steve March 28, 2012 at 9:54 am

@Rick, No, I would not bother. Black becomes hotter and that is what you are aiming for but not sure it’s worth the trouble. It would not cause to much a problem to paint but more than likely it will wear off in a year or two.

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CHERYL March 26, 2012 at 4:39 pm

hi Im about to start my own compost as I have been growing all my own vegies. I would like too know how long should I leave the compost before adding to garden beds.

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Steve March 28, 2012 at 9:51 am

@Cheryl, I keep my composter going until it looks like dirt, others will only wait for it to break down 60 to 75 %. Typically I let mine break down 4 to 6 months.

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Renee April 2, 2012 at 9:37 am

I have started a compost pile. It is just a bunch of rocks stacked in a ‘U-shape”. Do I need to cover it with black plastic or will it get ‘hot’ without it.

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Steve April 5, 2012 at 8:43 am

Renee, Yes you can cover it with black plastic, it will likely help increase the heat and keep the heat in. Make sure it still gets oxygen though and kept moist.

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Jenn April 15, 2012 at 3:15 pm

Hi,

I have a big covered 5 gallon bucket that I put food scraps, coffee grounds, etc. in and then I take it to my boyfriends farm and throw it in his big compost pile. I recently went on vacation and when I got back the scraps were a little moldy in the bucket, is it still okay to put the moldy food in the compost pile?

Thanks!

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lars April 16, 2012 at 10:42 am

@Jenn

It’s fine. Getting moldy is all part of the decomposition process anyway, so it’s no big deal.

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Karen April 17, 2012 at 11:45 am

Would the compost pile benefit from outdated vitamins or perhaps a “tea” made from them?

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Steve April 18, 2012 at 8:25 am

@Karen, I doubt it will be a noticeable benefit to add outdated vitamins but it will not hurt either. Yes I would dissolve them first, just to be safe, so a child does not see them and think they are candy.

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Sahari April 21, 2012 at 3:28 am

I’m wondering about the rhythm of things. Each night, I’m collecting my vegie scraps, but once I put my compost (aluminum trash can) together, then I don’t keep adding, right? Because otherwise I’m not giving it a chance to break down? So what do I do with all my scraps while I’m waiting for my ‘can to cook’? I always imagined composting meant just throwing stuff in a pile as you go… I know there are no hard and fast rules, but could use a couple example scenarios to help get my head in a starting rhythm. I’m a thankin’ ye.

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Steve April 26, 2012 at 11:19 am

@Sahari, You can batch compost, which means you fill it up and let it finish or you can add as you go and once it’s full then you stop adding. With both you will find a second composter is handy this way you have another bin to add material to once the first is full. If you are using a trash can make sure you add air holes on the sides and drainage hole in the bottom. Mix it once a week and make sure you have it moist as a will wrung out sponge.

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Jo April 22, 2012 at 12:30 am

Hi there. Over all a great list! But in the spirit of helping keep us healthy a important correction: A pig is not an herbivore and it is not recommended to compost pig poop in any circumstance. Caged exotic bird droppings should not in any circumstances be composted. The only bird droppings that should be composted is from poultry. There are serious potential health risks from using pig and exotic bird feces – especially if using the compost on food plants.

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Jessi May 5, 2012 at 8:12 pm

What about composting bread? I’ve read a lot of conflicting information about it.

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Steve May 7, 2012 at 1:37 pm

@Jessi, Composting bread is not normally recommended because it can bring it maggots, worms or mold, however some people don’t mind that.

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Pol May 11, 2012 at 6:27 pm

I have just bought a compost bin so I can cut down on waste and to save money on gardening, I have the bin sitting under a bushy tree it has an open bottom and a sliding door at the bottom to take the compost out when its ready. My Questions are, do i need to mix the material on a regular basis and do i need to add moisture or will it get the moister from the ground because of the open bottom? is it a bad place to have it because it is shaded from the sun light? thank you

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Steve May 16, 2012 at 12:45 pm

@Pol, You should try to mix or aerate your compost a few times a month and once a week if possible. Also keep it as moist as a well wrung out sponge. If you can move the compost bin over to a sunny spot it will help but not the end of the world if it’s in the shade or partial sun.

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Maritza Serrano May 13, 2012 at 12:36 am

Thank you very much for all this ideas. I already started my compose, I think that I need to mix everything. I’m using a black, plastic garbage can. No bad smell or flies around and again thank you very much.

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Becca May 26, 2012 at 7:27 am

How long can the compost sit once ready… Say my compost is ready by Fall, is it best to put on the garden for next year’s planting, or let sit in a pile and then spread in the Spring? Maybe it doesn’t matter either way? I guess I’m wondering, once composted, is it just like dirt – is there anything I can do to it at this point to hurt it, to make it lose it’s nutritional value?

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Steve May 30, 2012 at 9:11 am

@Becca, Your compost can sit unused for as long as you need. I keep some in a pile near my garden to add when needed. You may want to cover it with a piece of plastic to keep it from erouding and spreading with the rain.

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rockie June 4, 2012 at 12:42 pm

Steve, I have my compost pile all done now. It’s about 4 ft high, 3′x4′ wide. I layered it by browns and greens all the way up. I used old leaves that I raked from the woods and fresh grass clippings for my greens. I used some straw in between the layers for aeration and to help with matting. (I run my mower over the leaves that I’m collecting)
Should I let this pile cook for 3-4 weeks before turning it or start doing that in about a week or so. Someone told me that if I’m putting straw throughout, it takes the place of turning the pile because of the aeration.
I planned on using a rod to stick through the pile in various places every now and again. Would that work?

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Leslie June 4, 2012 at 10:25 pm

Hi, I am new to composting. I have a double compost bin that I got from costco. I’m hoping to start with my pile soon. Can I just start adding stuff to my compost bins or are there special steps that I need to take before adding items to the pile? Also while I reading what I could be composted, I saw something about worms. Do I need to add worms?

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Steve June 12, 2012 at 1:33 pm

@Leslie, Yes, you should start adding browns (carbons) and greens (nirtogen). A majority of the items you add should be browns, at a ratio of roughly 3 to one by weight. No, vermicomposting (worms) is different than what you are doing, you need a different type of bin for that.

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Leslie June 4, 2012 at 10:27 pm

Another questions; in the column next to the compost item, there is either nitrogen or carbon. What does this mean?

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Steve June 12, 2012 at 1:35 pm

@Leslie, Browns (carbons) and greens (nitrogen) and you need both, the list on the site helps you identify which category things fall in. Make sure your compost is moist but no soaked. You want it as wet as a well wrung out sponge. If your bin has holes, as it should, then the water will run out so don’t worry about over watering. Make sure you mix it at least a few times a month and if possible once a week.

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Beckie June 5, 2012 at 7:29 pm

We just bought a 120 gallon bin. We’re planning to regrade our yard in summer 2013, fix our beds, and create some raised veggie beds. Obviously it is going to take us awhile to create layers. Right now it is a lot of paper products (tissues & paper towels). I’ll be adding some leaves, but food waste, in the meantime, is obviously going to mold as it sits on the bottom. Is that a problem? Thanks!

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lars June 6, 2012 at 1:55 pm

@Beckie

Composting is just a fancy word for decomposition, which is another fancy word for rotting. Everything rots eventually, and all the different ways that things rot are just part of the process. When you compost “wrong,” it typically just means that you are doing it in a way that makes it stink or that makes it take an unnecessarily long time. You could even compost nuclear waste if you had 10 million years to wait for it to finish! Ha ha.

It is totally normal and fine that the food waste in the bottom might mold or attract insects or whatever else while it sits there, and none of that will hurt anything.

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jenilee June 8, 2012 at 5:55 pm

Hi Great info. I am making a pallet compost. I have lined it with chicken wire because I am up at altitude and have company always. The moose love my yard. I am wondering if i should also line it with the weed protecter from other critters? Also that will keep it hot because it’s black. Do I need a screen on the bottom of my pallets? I have it all enclosed on top because of animals.Also it is off to the side of garden over by aspen trees. Looks like its going to be healthy…Thanks…woodswomen

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Steve June 12, 2012 at 12:58 pm

@jenilee, I would not put anything on the bottom of your home made compost bin, unless its smooth like brink or cement. Anything rough will make it more difficult when you go to remove it, especially chicken wire, your shovel and pitch fork will get caught up in it. Weed barrier will help, just make sure it gets plenty of air and kept moist as a well wrung out sponge.

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Larry Tippetts June 14, 2012 at 12:09 pm

Does anyone know if 30-40 year old white beans and wheat from my food storage can be composted?

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Steve June 15, 2012 at 10:15 am

@Larry Tippetts, As far as I know it can be composted however the beans will need to be broken down if you want to compost them quickly. If you can break them or crush them it would help speed things up. Or make sure they get plenty of water so they get soft. Just toss the wheat in and count it as a carbon.

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Renee DeStefano June 29, 2012 at 2:53 pm

Can i put things in the compost that have salt on them?

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Steve July 10, 2012 at 10:38 am

@Renee DeStefano, Yes you can add items to your compost bin that have been salted unless you have a serious problem with salt and add half a jar to every plate full. A small amount should not be harmful.

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Bren July 17, 2012 at 7:30 pm

i added cooked rice to my compost ‘roller-barrel’. Now the compost smells bad. the rice was made in a rice-cooker. should i just dump the compost or is there a way i can fix it?

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Steve July 20, 2012 at 12:26 pm

@Bren, Try adding some browns and let it dry out for a few weeks. If it does not go away you may need to start over, but I suspect it will go away in a few weeks.

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Talia August 4, 2012 at 9:07 pm

I’m wondering if you can put used tissues in the compost when you have a cold and will it be harmful to the critters that live in there?

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Steve August 6, 2012 at 10:55 am

Talia, Yes you can add used tissue to your compost bin, and no, it will not affect anything.

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erin September 3, 2012 at 11:18 pm

Everyone refers to kitchen waste as “scraps” like potato, apple and carrot peels, but can you put molded fruit and veggies in the composter like tomatoes, peaches, etc.?

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Steve September 5, 2012 at 9:20 am

@erin, Yes, you can add fruit scraps but keep in mind they will likely cause fruit flies. Its not a problem for me since my composters are located in the back side of my yard, away from my house. Also, I bury the fruit scraps deep in the pile to help reduce the smell, etc.

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krissie September 4, 2012 at 8:34 am

Hi thanks so much for this list! Do you think baby wipes would compost, or not? I rarely use disposable baby wipes but i’d love to be able to be more earth friendly when i do use them!!

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Steve September 5, 2012 at 9:18 am

@Krissie, Baby wipes would likely break down in your compost pile. Toss a few in and see how it goes.

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Nancy September 7, 2012 at 8:14 am

Can you add shrimp shells from peeled shrimp to the compost pile, I say no and my husband says yes. Thanks for an answer.

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Steve September 11, 2012 at 9:03 am

@Nancy, Yes, you can add shrimp peelings to your compost bin, also try drying them out and breaking them up so they will break down quicker.

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Bill September 12, 2012 at 6:29 pm

Hi Steve, I have a couple raised beds and some beds along the house I use them for vegetables.Can’t I just take grass clippings and mulched leaves some hosta plants and mariogolds and kitchen scraps just put them on top of these beds let it sit there for a week or two and then just turn it all over bury and mix it up good with the soil.So I can plant in it next spring.I’m trying to enrich the soil because it has been planted too much and has lost most all of its nutrients.Then next spring maybe mix in some cow manure turn it all over and plant.
Thanks a lot Bill

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Steve September 14, 2012 at 9:57 am

@Bill, Yes you can add your clippings, veggie scraps, etc and put them on top of your planters but there is a fair chance it will just attract critters and not break down as quickly. I strongly suggest you make a compost bin or pile so you can contain the compost material then add it to your planters once its fully broken down.

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Josh September 21, 2012 at 1:18 pm

Nice list, but one quick correction: lime is not acidic. It is basic.

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lars September 21, 2012 at 1:30 pm

@Josh

Good catch! Fixed it. Thanks for pointing it out.

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