Cannas are prized for their large, lilylike flowers and variegated foliage. They grow well in all climates, though in areas with winter freezing they may need to be dug and stored indoors each fall. These plants require a reliable source of nutrition to bloom and thrive, which is most easily provided by implementing a regular fertilization schedule. Cannas only require nutrients when they are actively growing during the spring and summer months.
Things You'll Need
Spread 2 inches of compost over the garden bed prior to planting the cannas. Work the compost into the top 8 inches of the bed. Compost provides organic matter and nutrients to the soil and helps improve the quality of poorer soils.
Place 1/3 cup of 12-4-8 analysis fertilizer into each planting hole before setting the canna roots in. Mix the fertilizer with the soil at the bottom of each hole then plant the canna as usual.
Fertilize once a month beginning one month after planting. Apply 2 lbs. of a 5-10-5 fertilizer to every 100 square feet of garden bed. Work the fertilizer into the soil between plants, taking care to not get the the fertilizer directly on the foliage or stems of the canna.
Stop all fertilization in late summer, usually September for most climates. Fertilizing too late in the year encourages tender new growth that is more susceptible to cold damage.
In cold climates where the canna must be dug and stored indoors for winter, reapply the starter fertilizer in the planting holes each year. In warmer climates, begin regular monthly applications of fertilizer when the cannas first begin putting on spring growth.
Never apply more fertilizer than recommended. Excess fertilizer doesn't lead to more growth, instead it damages the plants.