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Dwarf cannas grow to about three feet tall. They come in a variety of colors, such as the bright red Ambassador or the City of Portland, which is known for its salmon color. Regular cannas are much larger in size, so dwarf cannas tend to grow better when potted. Potted cannas will grow in almost any potting medium that can be purchased at a garden supply store--they’re really not very picky. However, it must be soil that drains well, as cannas don’t do well with soggy roots and could develop mold. You will also have to choose your container based on the size of the variety of canna you are choosing to plant. If you are not sure how large your specific canna can grow, run an online search or ask someone to help you at your garden supply store. Remember, you can plant your cannas with other plants in your container, but just remember that all of the plants in one container must have the same water and sunlight needs or else they will not do very well. Plant your rhizomes (or tubers) in these holes, making sure that each dwarf or medium rhizome is at least 1 foot (.30 m) away from the next rhizome, unless you are planting them in a container, in which case you can often fit two or three tubers in a container. If you have a larger variety of canna rhizome, make sure that there is at least 2 feet (.61 m) distance between rhizomes. Make sure that the growing points (or eyes of the tuber) or pointing up. You should water your cannas right after you plant them so that the soil will settle around them and they can start to grow. When they have begun to sprout, water your plant as much as needed, keeping an eye on the soil to make sure that it is always relatively moist (though not soaking wet). It is recommended that you bring your cannas outside so that they can get full sunlight during the warm months. If you do choose to keep them inside, make sure they are near a window that provides them with bright sunlight for most, if not all, of the day. If you did bring your cannas outside for the summer months, make sure that you bring them back inside before the first frost has the chance to harm them. Store them indoors where the temperature stays at around 45 and 60 degrees F (7.2 to 15.5 degrees C). You can also dig up the rhizomes and store them in a plastic box with peat moss or perlite.
Consider buying dwarf cannas for your planter. Use well-drained, good quality soil. Purchase a pot with drainage holes. Dig holes that are 4 to 6 inches deep (10 to 15 cm). Water your cannas. Make sure your potted cannas get plenty of sunlight. Bring your pot inside before the first frost.