Calla lilies are typically grown in pots and should be fertilized to maintain healthy roots and encourage blooms. Fertilize in the spring and fall with a 10-10-10 fertilizer, discontinuing when blooms appear.
Fertilize when planting
Upon initial planting, fertilize the calla lily by inserting slow-release fertilizer spikes near the roots. This is more effective at distributing the fertilizer than inserting the spikes from the top of the soil.
Fertilize in the spring
Fertilize in the spring when the lilies break through the soil to the surface. Push the sticks as deeply into the soil as possible, spreading them out around the pot. The spikes may be placed on top of the soil. Water thoroughly so that the nutrients have an opportunity to disperse through the soil. The spikes should be removed if the foliage begins to show burned edges.
Fertilize in the fall
The calla lily responds well to fertilizer in the fall. Check the soil pH. If the pH level falls below 6 to 7, add lime to raise the level. Make sure that salts do not build up around the sticks due to improper watering. If necessary, repot the calla lily or remove the bulbs to begin again in the spring.