Growing Oregano and Sweet Marjoram:

Oregano (Greek) and Growing Sweet Marjoram — These herbs are in the same family, have similar flavors and are very easy to grow. They both like full sunlight and will get quite large. Oregano creeps along the ground growing up to 6 feet around in a single season. Marjoram grows mostly upright can be 2 feet across and tall. Both are somewhat tender perennials which probably grow back in the spring in most areas.

To harvest Oregano or Marjoram, trim the branches anywhere and cut off up to a third of the plant, and chop the leaves. You can also dry the leaves which gives them a slightly stronger flavor.
To use Oregano and Marjoram in cooking, chop the leaves finely. Sweet Marjoram is a bit stronger than Oregano and used for flavoring meats along with garlic and onions in many Mexican and Greek dishes as well as on pizzas and tomatoes. Both can be used interchangeably in recipes. Most Italian mixes of spices include basil and sometimes thyme. These two add dimension to salad dressings and marinades especially when combined with other herbs.