Almost any plant can be potted and successfully grown in a container. Perhaps the most important element in succeeding at this is to use a potting soil that is the most beneficial to each type of plant. The same soil used to successfully grow cacti and succulents will not produce satisfactory results on garden vegetables. Even seeds and young transplants benefit from using a soil mixture tailored to their needs.
Seed Starting Mix
Seeds started indoors to get a jump on the gardening season need a sterile seed-starting mixture. Small transplanted seedlings or cuttings also will benefit from the use of this sterile medium. Use a seed-starting mixture of 1 part peat moss, 1 part perlite and 1 part sterilized soil or compost. This mixture is virtually free of bacteria and other soil microbes that can cause a condition called "dampening off," which is when young seedlings inexplicably collapse and never recover. It most often is caused by soil-borne bacteria.
All-Purpose Growing Mix
To grow everything from indoor plants to flowers to vegetables, use a potting soil mixture that is loose, friable and holds enough moisture so the plants do not dry out too quickly. Mix 1 part peat moss, 1 part garden loam soil and 1 part coarse builder's sand. As each plant is potted up, add a balanced, slow release, all-purpose fertilizer to each pot, following the manufacturer's recommended rate of application. This mixture drains quickly, holding just enough moisture to keep the plants hydrated. Thanks to the addition of the sand, it is heavy enough to securely anchor the roots of demanding crops such as tomatoes, peppers and other garden vegetables.
Cacti and Succulents
Native to hot and dry deserts with sandy soil, cacti and succulents need a similar type of soil mixture when grown in pots. For an all-purpose cacti and succulents potting soil, mix 2 parts garden loam or potting soil, 2 parts sand, 2 parts peat moss and 1 part perlite. The loam or soil will provide organic nutrients while the sand lightens the mix, providing quick drainage. Peat moss improves the soil's structure while retaining moisture. With its light-as-air, irregularly shaped particles, perlite is primarily used to lighten soil mixtures, which increase aeration and improve drainage.
In nature, most orchids grow by attaching themselves to the bark of their host trees. As such, they will not survive for long planted in regular indoor potting soil. Orchids must be grown in a light and airy mixture comprised of large particles that create large air pockets and allow water to drain quickly. For an easily mixed orchid growing medium, combine 5 parts fir bark and 1 part perlite. The bark will hold just enough moisture for the orchids and the perlite will help to create more and irregular air pockets in the shredded bark.