I am not alone in getting these plants confused. Marjoram is the sweeter, milder, softer option but they are all members of the origanum family and related to mint. Origanum vulgare is what is usually regarded as oregano while Origanum marjorana is marjoram (sometimes referred to as sweet marjoram). It also has smaller leaves. I grow both and tend to use them in tandem when cooking. It appears that in the wild and in harsher climates, oregano develops a much stronger taste and the flavour difference is marked. But in our soft and lush conditions, the flavours of both are very mild.
The relationship to mint gives a clue as to growth habits. These are clumping perennials, easily increased by division once established. In colder climates they are largely deciduous, but grown in a well cultivated garden border, I can harvest from them for most of the year. It is best to divide them in spring or summer when in full growth. If you are growing oregano for cooking, don’t succumb to buying the golden and variegated forms which lack the flavour. You can plant these herbs as ground cover in herbaceous borders though they can be so enthusiastic in growth they may swamp more retiring neighbours. They will grow happily in sun to part shade but the flavours will be intensified in harsher conditions – full sun and poorer soil. I have decided I am being too kind to my plants and am getting masses of lush leafy growth at the expense of flavour. Their Mediterranean origins are an indicator that they will take harder conditions. What is sold as Greek oregano is reputed to have the strongest flavour.
First published in the Waikato Times and reprinted here with their permission.