I've grown single peppers in 2.5 gallon containers and single peppers in 5 gallon containers on my deck. There is a slight size difference in total plant growth but in the end the pepper production was very similar. The main difference is watering frequency. You never want your peppers or any plant to be in a container that completely dries out. As a gardener that is the main issue when making decisions about container gardens... can you maintain the moisture and nutrients/feedings? Bigger containers and fewer plants are more forgiving when it comes to those two issues.
If the answer to the question above is yes, you can grow 2 pepper successfully in a single 5 gallon container. The key is to have a back up water reserve in some capacity just in case you miss a scheduled watering. Watering becomes a bigger issue when the heat of summer arrives. If you were to grow them on a deck... you would need some sort of watering tray for them to sit in during the hot weeks of summer. You can also use containers on the ground. The video shows you how to set up a 5 gallon container for a ground contact pepper container.
All ground contact means is a container with a good size hole in the bottom where the container soil and developed roots of the plants can contact and grow into the ground. It is your back up watering system so to speak. The hole is also key for drainage. Peppers hate prolonged wet soggy soil. The video covers the basic set up along with a general soil preparation with a basic ratio for organic matter. Organic matter, be it compost or peat moss, is your water retaining agent. Don't worry, if you don't feel like messing with soil mixes, any water control store bought garden soil mix will work just fine. Enjoy!
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