Answer: Bagged organic humus can be made from a number of different materials, and in general the texture is too fine for healthy root growth over time. Bagged topsoil can also consist of a wide variety of soil types, so it is possibly more predictable to use a potting mix intended for container plants. Such a mix should be both well draining (to allow air to reach the roots) and water retentive (so it doesn't dry out too fast) as well as provide at least some initial fertility for the plants. The commercial mixes are blended from any number of ingredients (some are soil-less) and are calculated to provide a good growing medium. In general, for vegetables you can add some bagged compost or ground bark or organic humus at a rate of one part compost to three parts soil mix. For more information on soil mixes and growing all kinds of plants in containers including peppers, you might like to look at some reference books. One I particularly like is "Container Gardening for Dummies" by Bill Marken, ISBN0-7645-5057-8. In it you will find plenty of good straightforward information and even recipes for making your own soil mixes if you want to try it. Good luck with your peppers!
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