These bulbs have different light requirements. Cannas are sun lovers and caladiums are shade fans. You can actually plant the two in the same pot. Look for such as Black Knight, Gypsy Rose and Florida Elise. Or better yet, experiment yourself and see which combinations you like best or which seem to perform the best in your location.
Start caladium tubers in a smaller peat pot indoors, if possible. Then transplant outside in containers. Be sure your pot has drainage holes. For small to medium containers, use the dwarf varieties. You can plant the tubers directly outside after May 30, when the ground is warm and they will grow well, but just a little slower.
Put in a lightweight potting soil and fill to about 2 inches from the top. Plant the tubers about 2 inches deep, placing the tubers with the growing points facing upward and the roots pointed down toward the bottom of the pot. Leave around 2 inches from the soil to the top of the pot for watering.
Water the potting soil and keep it moist. Caladiums like it more wet, but not too damp or the tubers may rot.
Fertilize them three to four times a month. Feed the caladiums with a balanced fertilizer, such as 20-20-20. If you have chosen a variety with some white, feed less to be sure that the white color stays in.
Discard the tubers after the first frost. You can overwinter the bulbs like a canna bulb, but usually they are treated as an annual for the most vibrant coloring.
Cannas Select a very large pot for cannas. By large, this means at least 20-24 inches in diameter. If you are planning on different varieties or mixing with other plants, plant them a minimum of 8 inches apart.
Place the rhizomes 2 to 3 inches below the soil line. Allow 2 inches from the soil surface to the rim of the pot.
Place the rhizome horizontally in the soil. Try to place any visible growing points so they are pointing upwards. The best part is there is no up or down on cannas, so don’t worry if you think they are upside down.
Plant the rhizomes as early as possible, perhaps in April and let them grow inside until you have at least 50 degrees for the evening temperatures.
Water the plants as soon as you have planted the rhizome. Keep the soil moist, not wet. They do not like really hot sun, so try to have a place for the pot where it is not direct sunlight around 12-2 p.m. Feed the bulbs about once a week with a balanced fertilizer, such as 20-20-20. Another option would be to mix a granular fertilizer at the time of planting.
After it freezes, cut off the black stalks and dig up the rhizomes, store them in boxes after they have dried out. Keep in dry peat moss, perlite or vermiculite. These can easily be replanted in the spring. Discard any mushy bulbs.
Try combinations with both of these bulbs. The leaves compliment many other plants and leaves: Ruby coral bells, the Japanese painted fern; hostas can be added to the pot and then replanted before frost into your gardens.
Caladium combinations: Annuals such as colored coleus, ivy or impatiens.
Canna companions: Tall ornamental grasses really add color and interest. Try reed and fountain grasses; try to find some with burgundy or reddish in the leaves.
Bright colors, such as pink, red and burgundy will look nice as well. Try Lantana, petunias, even shrub roses for different and interesting combinations.
Why not think leaves when you plant containers? With all the wonderful foliage plants on the market today, it makes a grand statement for your containers. Cannas and caladiums are the perfect way to start a unique and eye-catching container for your living and garden area.
My favorite source for caladium bulbs: Happiness Farms; happinessfarms.com, telephone toll free (866) 892-0396.
Cannas: Horn Canna Farm; cannas.net, telephone toll free 800-365-5528.
If you have any trouble with these companies contact them. I have had good service from them.