Marjoram is one of Europe's essential herbs, much used in southern European cookery but not so much here. It is also is the subject of some confusion. The native plant, wild marjoram, Origanum vulgare, is usually refered to as ‘oregano' once it is in the kitchen - but this species includes quite a variable range of plants, from both gardening and cooking points of view. Those with a Southern provenance tend to have a far stronger flavour than our native plants.
Sweet Marjoram, also known as knotted marjoram, Origanum marjorana, is the form that seems to be the most natural accompaniment to thyme and basil in so many dishes, particularly those including tomatoes. It has a sweet, soft flavour, similar to thyme but sweeter. It blends very well with the pungency of sage for stuffings. Pot Marjoram, Origanum onites, is also widely grown for culinary use, somewhat similar to sweet marjoram, but lacking its sweetness and fine flavour.
Both pot marjoram and wild marjoram will develop into attractive large clumps quite quickly, looking good in either a herbaceous border or a herb garden and are delightfully perfumed. Sweet marjoram has a more straggly growing habit. The flowers are very attractive to bees and hoverflies. All are perennials and are easy to grow, but sweet marjoram is not hardy and will only survive a winter in a very sheltered situation or when grown under protection.
Although both pot and wild marjoram usually retain some leaves throughout an Irish winter, a supply of better quality fresh leaves during the colder months is assured by having one or two plants inside. Marjoram will grow quite well in a pot on a windowsill, but its vigorous growth will mean that after six months it should either be potted on, or planted out.
Propagation can be achieved from seed, cuttings or division. Marjorams grow best in a sunny, open situation on well-drained fertile soil. They are almost free of significant pest or disease problems, and will require almost no attention other than to cut them back after flowering. It is advisable to lift a clump after two or three years, divide and replant.
The ornamental forms of marjoram are of little culinary interest, although golden marjoram Origanum vulgare ‘Aureum', which lends such a cheerful, sunny hue to a garden bed, has leaves of a delicate flavour and texture which are attractive as a garnish. A particularly striking visual effect can be obtained using a mass of golden marjoram and a green leaved marjoram in a herb bed - but in this case it is best to keep the plants well clipped to maintain the maximum colour contrast.
For culinary use the leaves of marjoram are stripped from the stem, and are generally best added shortly before cooking is completed. The flowers (or knots - from which sweet marjoram derives its other common name) can be used as a visual and flavoured addition to salads.