I have a 28 x 28 inch deep wooden planter on my terrace. It gets full light and has an auto drip system. I love cilantro/basil and parsley to name a few herbs. I have had problems keeping the herbs thriving – wanted some help with space and species planning for this space. Not sure how much or little I can plant but I want to max out what I grow. I have to say kale from last year popped up this spring to my surprise. Any suggestions would be most appreciated.
Thank you for writing. Most herbs do well in containers, so you can choose the herbs you like to use the most. Your container is not all that large, so I would not recommend you plant perennial herbs as they likely won’t survive the winter. If you treat them as annuals, they will work fine. Some examples of perennial herbs are chives, sage, rosemary and thyme. Rosemary is a tender perennial so you would actually need to bring it inside for the winter if you want to keep it. It can also become quite a large bush. Cilantro, basil and parsley would do very well together.
I would say that you could plant 4-6 herbs in your planter, depending on the initial size of the plants. Parsley can become quite big. Use a good quality soilless potting soil for good drainage and I would change most of the soil in the planter since you said the herbs didn’t do well last year. Herbs in containers also need to be fertilized. You can use a granular organic fertilizer or a liquid or powder dissolved in your watering can. Follow the directions on the packages. I know you said your container has an automatic drip irrigation system, but perhaps they need a little more water on hot sunny days than that provides. Most herbs also require a full sun (> 6 hours direct sun) location. Some annual herbs, such as cilantro and basil, can flower quickly if you’re not picking the leaves. Pick from the tips to encourage a bushier plant. When they’ve flowered, they go to seed and are pretty much finished. You would need to buy some new plants to finish out the season. I have found that cilantro and basil often need to be replaced. Cilantro is one of the few herbs that can use a little bit of shade to keep it from flowering too quickly, but it will do well in full sunlight as well. Keeping cilantro well watered and fed will also help prevent early bolting. Your cilantro plants will eventually flower, however, no matter what you do. Luckily, its flowers attract hoverflies, which eat aphids.
Mint is another perennial herb which almost should be planted in containers as it can be invasive. It should also be kept in semi-shade.
Here is a link that will give you additional information:
Toronto Master Gardeners have a gardening guide on growing herbs but it doesn’t have specific information for containers.