Growing Oregano from seed in March is ideal if kept inside, if you want to sow them directly into the garden, it is advisable to wait until the ground has warmed up, about the end of May to the beginning of June.
Sow in pots with 4-6 seeds per pot. If you prefer you can sow more into the pot and then thin out the weaklings. Germination can be difficult and sometimes it may take up to 6 weeks. If the seeds have not germinated by this time it likely that they have died. You do not need to put the pots into the light, but they must be kept warm.
Once the seedlings have grow a little, transplant them, taking care of their fine root system, either into a container or into the ground.
When sowing directly into the ground sow them thinly, do not actually bury them, press them into the ground and water them regularly. Rather than spend time thinning out it is easier to stop watering the weaker seedlings if possible.
Once the plant has established it will throw underground stems, utilize these by digging the plant up every 2 or 3 years and dividing into 3 or more separate plants. This will also help stop the plant turning woody. Oregano only needs to be watered once or twice a week during dry periods. By not adding any fertilizer stronger flavors will be produced.
When the plant has reached about 5cm tall and has at least 12 leaves you can begin harvesting. When harvesting oregano pick the leaves first thing in the morning, after the dew has dried, because once the sun warms up the leaves they lose some of their oils, it is the oils that give both the smell and taste. Cut tender young stems, this will also help to keep the plant producing new growth.
When the plant reaches about 8cm tall you can cut back the whole plant and it will re-grow and produce another crop of tender young leaves. Pick any flowers as soon as they appear otherwise the leaves will turn bitter, and left un picked the flowers will of course turn to seed which will self propagate and you will have oregano in abundance.
Growing Oreganoin a container is usually successful as long as you remember to bring it inside during the winter and put in a sunny position. You only need to water container plants during the winter when the compost or soil is dry, if you over water the plant will rot and die.