Things you'll need:
At least 2 large pots (at least large enough to hold lots of dye and your fabric)
Strainer
Vegetables or fruits (I'll get to which ones work well in a second, but get more than you think you'll need just in case)
Pre-washed Fabric (100% cotton, muslin, silk, or wool work best, because synthetics are made not to absorb things)
1-2 Tbsp Alum Powder (you can get this in the grocery store in the spices section)
Step 1:
Choosing your vegetables/fruits
Now, there are a lot of great colors out there in nature, but not all of them will work very well for dyeing things. I'll tell you now that some things just don't get absorbed well, and so if you're looking for brighter colors, you may need to do some research. Here are a few links to help you decide on a material: http://www.pioneerthinking.com/crafts/crafts-basics/naturaldyes.html and http://all-things-shelly.blogspot.com/2011/06/how-to-use-natural-dyes.html really helped me out.
I started with red cabbages. I bought two heads of red cabbage for this project because I had a lot of fabric.
Step 2:
Prepare you veggies!
You'll have to chop up your fruits or vegetables to prepare them. For me, it meant chopping up my cabbages into relatively small pieces and tossing them in a large pot. After that, you add water to cover the veggies and then maybe double that, so if you have two inches deep of cabbage, you should have four inches deep of water.
Step 3:
Cooking
Put the large pot on the stove and start to boil the veggies/fruits. Probably don't let it boil the whole time, but turn it down to a simmer and let it sit for about an hour while all the color drains from the plant (some dyes take less time, so just check it until it looks pretty good).
Then you need to strain the plant from the water, which I did by pouring it through a strainer into another large pot but which you can do however you please. This way, you should have just your dye.
Here's what my cabbage dye looked like. As you can see I did not have a particularly large pot so put it into two when I strained it. But then dumped it back into the big one.
Step 4:
Alum Powder
This is incredibly important and my fatal mistake. In many websites they say to separately soak the cloth in alum and water for an hour, then rinse it out and dump it in the dye. However, this did not work for me at all! I found a site that said that it works better when you put the alum in WITH THE DYE. So here's what you do:
Take a cup, put about a tablespoon of alum powder in it, then fill it will hot water from the tap and let it dissolve. This way you don't get spots like this:
For some reason if alum clumps it will just do weird things... Notice that this is not a very nice color either. I definitely did something wrong, because it was supposed to be a light purple and it turned out gray. This is my first attempt with cabbage.
If you want to know more about alum and what it does, check it out on wikipedia http://en.wikipedia.org/wiki/Alum. I just know it as that stuff that acts as a fixative for dyes.
Anyway, once you've dissolved it into the cup, just add the cup to the dye and mix it up well.
Step 5:
The Fabric
At this point add your fabric to the dye bath. You'll want to swish it around if you have room and make sure it all gets covered with the dye. Here are a few examples:
This one is blackberries
Here we have my second attempt with cabbage and muslin
This is the sadness of the first cabbage bath
This one, surprisingly, is onion skins
So yeah. Try to get it all covered and pretty looking. If it doesn't look like it's taking the dye, it's probably not taking the dye.
Once you've got all that done, let it sit for at least an hour. I left some of mine in overnight just in case. But you should be fine with an hour or two.
Step 6:
Finishing it up
Once you get the color you want in the dye (which may be a different color than you expected), then take it out and rinse the whole thing out until the water runs clear. I just used the sink because it was big enough, but you can also use a bathtub, which may be easier if you have access to one. Or a shower. Hell, you can use a hose and it will work. I suggest cool water simply because it's easier on the dye and the fabric.
Once that's done, just hang it up to dry! You could also twist it and leave it to dry that way if you want a different look. There are a lot of cool ways to let things dry.
Here are my finished products:
This is the lovely yellow I got from the onion skins
Here we have my final pieces of fabric, with the yellow onions on the top, the cabbage that worked in the middle, and the blackberries on the bottom.
The best part is you can store the dye you didn't use for later! If you put it in the fridge it won't mold and you can dye eggs or other fabric at a later date. Here's my egg project for Easter!
The yellow came out a lot lighter on the eggs, but the cabbage is the beautiful medium blue and the dark blues are the blackberries, which I find interesting since they produced more of a reddish color on the fabric. But hey, that's the lesson about dyes: They're always a little different (or a lot different) than you expect them to be.