You know the best thing anyone that likes to cook can have is an herb garden, of course they are always better if planted in the ground, near the kitchen door where you can easily reach them while cooking.
However like so many people space is always at a premium, so containers are better than nothing. I have found that while many sites and magazine articles often show collections of small pots of herbs, that looks camera lens friendly and even better in print, the truth is nice large pots like you think a small tree would be planted in is great.
The reason being is that the root systems need plenty of room for growth and also more space for water retention. The number one key to gloom an doom in container gardening, is lack of water. While we all (myself included) start out great at the beginning of the growing season, fresh plants, fresh soil, water it looks so nice and green, they grow to a nice lushness, then reality sets in, blistering hot 90+ degree weather with 100% humidity, they will be ok if I wait a couple day to water them……..NOT!!
The reality is even with a larger pot, that if the pot gets 6 hours or more sun per day, they should be thoroughly watered and deeply, not just a bucket (if a large pot) you want to make certain it is thoroughly watered, you should check with your finer down in the dirt each day and see if the soil is drying out rapidly in the heat.
Once plants bush out over the top of the pot, they will act as a protective mulch helping to shade the soil, and helping with evaporation beyond what the roots take up.
I had used large 20 to 24 inch diameter pots. I still had to water at least 3 times per week, once the plants got large, they will reward you with bounties of fresh herbs.
I also planted onion sets in the pots early on in the spring, along with some lettuce, and some Nasturtiums, Violas, and Pansies, are nice early spring choices to brighten your early pots, before the heat becomes to warm for the spring crops. Then if the pot is large enough I will remove those and stick a geranium in the pot, Geraniums love heat, this brings some color to your container garden.
Before I moved (and had give away all my containers) sad day! I planted the following herbs in my containers
Rosemary, Basil, Oregano, Thyme, Spearmint (separate pot) all to itself (for mint tea) Tarragon, Lavender, Chives, Garlic Chives
One thing to remember when planting herbs in containers is over crowding, it is far better to have more than one container if you are planting a lot of herbs, as it is really easy to think that is a huge pot with very few herbs, but over crowding any container with plants herbs or otherwise can be a sure demise of your container garden. Over crowding causes competition for water, root growth and sunlight as well as good air circulation, which in turn can cause molds and diseases.