Indoors or out, container plants are confined to a limited space and can't pull from nature in the same manner as in ground plants, making the “soil" you choose for them to grow in very important. Don't choose top soil, garden soil or pure compost. These are too heavy and will quickly lose porosity, as they compact in the enclosure of a pot - eliminating the air & water movement space needed for plant roots to grow.
Look for special mixes for Orchids and for Cacti & Succulents. If you are starting from seeds look for seed starting mix. What's known as all-purpose potting soil or mix will serve your other container plantings well. Be cautious if you buy a moisture control potting mix. They work well for short term outdoor plantings, but lose their porosity over several months - again, resulting in too much water and too little air for roots.
If the range of choices leaves you unsure, check out these recommendations. A two year study, at Colorado State University, found the following commonly available products to offer healthy growth and performance in containers:
- Home & Garden Showplace Professional Mix
- Fertilome Potting Mix
- Nature's Yield Potting Soil
- Southland Potting & Plant Mix
- Black Gold All Purpose Mix
- Permagreen General Purpose Potting Soil
- Schultz's Instant Potting Soil Plus
- Sunshine All Purpose
If you prefer to blend your own potting mix, check out the helpful recipes at Hobby Farm Magazine's website, then head to a farm supply or well-stocked garden center for the ingredients and get planting!