To make the teabag, lay a double layer of cheesecloth on a bare patch of soil and place one or two cups of compost, aged manure, or slow-release organic fertilizer on it.
If you want to make your own organic fertilizer combination, use the following ingredients (all of which you should be able to buy in bulk at a farm supply or feed store; they'll keep for years if kept dry):
Place the tea bag in the bucket, and fill with water and let it steep for a day or so.
When the tea is ready, remove the bag, and fill the bucket the rest of the way with clear water to dilute the tea. You can treat each of your plants to a cup or two of tea.
As a rule, underfeeding is better than overfeeding, and small regular feedings are better than occasional large ones.
Source: The Sierra Club
Using coffee grounds without heating for indoor plant fertilizer has produced flies.
How long do I bake and what temp is good to sterilize them?
They have been boiled, are as close to sterile as anything. Mix well with soil, add minerals.