There are more than 2,000 different species of begonias with a wide variety of shapes and colors of flowers to choose from. They can be grown trailing over the side of a container, upright in pots or in the garden. They bloom from summer to first frost. You can grow them from small plants bought at nurseries, or from tubers. Tuberous begonias are susceptible to frost, but with proper care can come back year after year. Wax begonias tend to be compact and upright and are usually grown outside as annuals.
Begonias can be easily and successfully grown in containers if you follow some general rules: use a pot fitted to the size of the plant, use the appropriate soil and provide the right amounts of sunlight, water, food and care.
Containers to Use
Use a small, clean pot for your begonia. If you are reusing a pot, make sure it has been cleaned with soap and water and sprayed with bleach to get rid of bacteria and any diseases left in it. A small pot is fine for one begonia, as they have a small root ball. If you are planting more than one in a pot, choose a large enough pot to provide adequate room. A two to three inch tuber or root ball needs six to eight inches of space to provide enough room for roots and growth, so a six to eight inch diameter pot will work just fine. An advantage of using small pots is that you can have different colors or varieties in several small pots, which can be easily moved and attractively arranged in your garden on plant stands, porches, decks, balconies or steps. Begonias in containers can also be rotated to promote even growth and blooms on all sides.
Begonias need to be planted in a good draining soil that's free of disease. Do not use soil from your garden or from a pot in which another plant has been planted. Use a commercial or homemade potting mix which is free of insects, diseases and weed seeds and provides good drainage. A great choice for begonias is a "soil-less" potting mix. Soil-less mix is not susceptible to disease, provides good drainage and aeration and retains water without becoming soggy. Soil-less mix is usually composed of peat moss with vermiculite and perlite, and can include compost or other nutrients.
Begonias need filtered or light sun but need to be protected from direct sun and wind. Keep the soil moist but not soggy. To test, stick your finger in the potting soil and if it is dry at the top, water. To avoid fungus or mildew, don't get water on the leaves. Fertilize your begonias regularly, as nutrients can be washed out of the soil by frequent watering. Keep your plants clean and healthy by cutting or pinching off dead leaves and spent flowers. An advantage of using containers for your begonias is that they can spend the winter in a frost-free place and be put back outside in the spring to start flowering again. Give your container begonias a proper start and they will continue to provide color and beauty in your garden.