You'll need a yogurt maker or a spot that can hold a temperature of 110°F for up to 12 hours, a pan, thermometer and containers to culture in if your yogurt maker doesn't come with jars or an insert. A small container to keep your starter for the next batch is handy.

Do notuse more starter than recommended. Using too much starter can crowd the bacteria, causing the bacteria to run out of food before the yogurt completely ferments the milk. The result is often a thinner, sometimes bitter, yogurt.

Yogurt cultures are a carefully balanced combination of bacteria that will produce a particular type of yogurt. Mixing different cultures or bacteria together may cause the culture to weaken or die.

To ensure your culture lasts indefinitely, you must re-culture at least every 7 days to maintain viability.

• There are a number of steps you can take to make your yogurt thicker.
  
  Change the milk you are using, the higher the fat content the thicker the milk will be.
• Increase the fat content by adding heavy cream on top of the milk.
• Heat the milk longer, the higher the temperature and longer cook will create a firmer yogurt.
• Strain the yogurt by draining the whey away from the yogurt to remove some water.
• Add thickeners that can be found on this page here 

You will know that your yogurt is set once it appears less uniform and looks more like one solid mass. The yogurt should be relatively smooth and should be able to be easily pulled away from the side of the container. Sometimes the whey will separate during this process, but you can just stir it back into the yogurt or strain it out.

Finished yogurt will last in a refrigerator at (40º-45º F) for 7 days to maintain re-culturing viability and 2 weeks for edibility.

Non-dairy milk will not work to activate an heirloom starter. It must be activated using pasteurized dairy milk. 

Milk that is “too clean”such as ultra-pasteurized/UHT milk, or milk that has been heated by microwave, may be too sterile for the yogurt culture to use as nourishment.

Our yogurt starters are in a freeze-dried state. To safely activate them, we recommend using pasteurized milk (not ultra-pasteurized). To use raw milk, please follow instructions for Making Raw Milk Yogurt.

Making yogurt at high altitudes causes it to set faster. With that in mind, putting yogurt into culture overnight might not be wise if culturing at a higher altitude.

To avoid interfering with the culturing process, it is best to flavor after the culturing process is complete. This is most important when working with heirloom cultures. For ideas for flavoring homemade yogurt, check out our list of Five Ways to Flavor Homemade Yogurt. 

n the refrigerator (40° to 45°F):

• 7 days to maintain re-culturing viability
• 2 weeks for edibility.