If your plant were moldy, it’s more likely to have white or grey spots. Are they really black or brown or dark green? Without seeing them, it’s difficult to be certain, but they are probably dry.

Fit for consumption? This is also difficult to say at a distance, but here’s a thought: It is advised to cut green stems in fall and hang them to dry in a cool, dark, well-ventilated place. When the leaves become dry, it is advised to remove them from the stems and store them in containers. Does this sound like your treatment? your leaves?

You might crush a few, and smell them. Assuming they were not damp, display no mold, and crush (not mash as rotted or damp leaves might), they are probably fine.

Leaves on oregano can be used at any stage of growth. In fact, cutting back blooms will stimulate growth.

Is this plant oregano (and therefore a perennial)? Was the plant transplanted directly into the ground during summer, or kept in a pot? The plant could be under stress for various reasons–could be transplant shock, from potting up from the outdoors and moving to an indoor location. If so, the plant might recover after a while. Also, some plants go dormant in winter, although gardeners usually can get oregano to produce throughout the colder months on a windowsill. Check for insects that may have come in on your plant, and monitor for disease. If you think the plant is not getting enough light, add grow lights (available from garden centers). Make sure you are not watering too much (allow soil to dry a bit between waterings), and that the pot has good drainage. Also check if it is too close to the glass or in a cold draft. Hope this helps!

You should harvest only the leaves. If you are harvesting the entire plant, let the flowers set your schedule: Harvest just before the buds open. (If you happen to miss that this year, no worries.)
 

If you're putting the oregano in a container, you can move the pot indoors in the winter. For plants in the ground, you need to protect them with lots of mulch and even a cold frame.

Your oregano plant will benefit from an annual (or, depending on its growth habit) pruning. It should produce more leaves.

Oregano is a tender-leaf herb. Try hanging a small bunch inside paper bags to dry. Punch holes in the sides of the bag. Close the top with a rubber band. Put in an area that has air circulation (and not above a stove). It generally takes approximately a week or so for herbs to dry completely.

Hi, JoAn: We think you'll find that 4-inch pots are wayyyy too small for oregano to flourish, unless you really plan on almost constantly harvesting them, almost like a bonsai project. Let them grow in full sun for now and see what happens. If you find that their growth starts to stagnate (because they are rootbound, no doubt), then transplant them into pots at least 3 times bigger. Or, do that now and save them the stress later. Thanks for asking!

It may be too soon to tell if the plant is gone. Look for signs of new growth or returning growth.
Of course, if this is a plant that you want to harvest to cooking and eating, its survival may be a moot point. Just to be on the safe side, it's probably wise to get another plant.
 

Most oregano varieties bloom, some more than others. Try to give the plant as much sunlight as possible and it may reward you with blooms.

There are many varieties of oregano and some have variegated leaves and some bloom more than others. Oregano needs full sun and warmth to grow well. Trimming the ends of the stems will make your plant bushier and more productive. You can propagate oregano by taking stem cuttings and dipping them in rooting hormone before planting them in a pot with equal equal parts perlite and peat moss.

No, these are different plants.

Mediterranean perennial herbs such as oregano and thyme have similar soil and watering requirements. They need full sun and slightly dry soil. Mint needs to be in a separate container or place; it prefers partial shade, moderate water and cooler temperatures. Also, mint spreads quickly and can take over other plants.

Of course, you can eat dried oregano. If you wish, let the dry leaves fall off, collect and crumble them up with your fingers to make them powdery, and put the dried herb into airtight jars to keep. 

Dried oregano is a way to save the herb for the winter months in areas where the plant dies back in the winter. The flavor of fresh oregano is most intense in mid-summer just before it blooms and some people like to dry the leaves during this time. Oregano is a hardy perennial and will come back next year.