Note how the sun lights your porch throughout the day. If you receive only early morning light, consider herbs that prefer partial shade. If a portion of your porch receives six to eight hours of sunlight a day, this is the ideal location for your porch garden.
Porches are often designed to provide shade throughout the day, however. Consider adding lighting fixtures for your garden.
Determine which herbs you wish to include in your garden. As you make your list, research the individual herbs' watering and lighting needs. Make another list in which you group the herbs together according to similar needs.
Decide what types of containers you wish to use. Clay pot containers are porous, so are less likely to cause waterlogged root systems. However, because water dissipates quickly from these containers, you may need to water more frequently.
Fiberglass pots are lightweight and attractive. Concrete or ceramic planters are likewise attractive, but are heavier and difficult to move around.
You can use a combination of container types, basing your decisions on the plants' needs.
Draw up a plan. Make a rough sketch of the porch and draw circles to represent the containers. Keep the containers in one general area of the porch, making sure you have access to water. Take advantage of the natural light for light-loving herbs and allow shade-lovers to reside closer to the house or in the shady area of the porch.
Write which plants will be in which containers, grouping together plants when possible. By planting two or three herbs with similar needs in one large container, you use your limited space more efficiently.
Purchase your containers and a potting soil designed to support herbs. Purchase herb seedlings and/or seed packets of your choice. Obtain a large watering can.
Lay out a large tarp on your porch near your garden spot. Start with the largest container and begin planting your herbs and placing your containers according to your plan.
Add your portable lighting if necessary. Use your watering can to gently water all your new plantings and then water according to need.
Continually harvest your herbs to encourage new growth. You may find you have an abundance of herbs, more than you can use. If so, you can dry the herbs, ensuring a supply into the winter months.