In their preferred growing conditions, chrysanthemums (Dendranthema x grandiflora) produce plenty of fall blooms, and in warm climates they offer spring flowers. But chrysanthemums growing in shady or wet conditions may not flower, and overfertilization encourages leafy growth while discouraging blooms. Hardy in U.S. Department of Agriculture plant hardiness zones 8 through 10A, chrysanthemums grow 1 to 2 feet tall, depending on the variety. Flower colors include brown, red, red-orange, white, yellow and pink.
Avoid Shady Spots
Chrysanthemums grow in partially shaded areas of the garden, but blooming is reduced. In full shade chrysanthemums grow poorly and may not produce any flowers. Remove overhanging foliage or other sources of shade, and the following year grow chrysanthemums in a spot that receives at least six hours of sunlight every day. In hot climates, grow the plants in sunny spots that don't receive hot afternoon sun.
Prevent Wet Conditions
Soggy soil can prevent chrysanthemums from flowering, and it can cause root rots. Chrysanthemums must have freely draining soil to bloom well. Overwatering or poorly drained soil drowns their roots, and over time this kills the plants. Signs of drowned roots in chrysanthemums include yellow leaves that blacken and drop.
Water chrysanthemums when the soil is dry to a depth of 1 inch. Apply enough water to moisten the soil to the depth of the plants' root balls. If the soil never dries to a depth of 1 inch, or puddled water takes longer than 10 minutes to drain away, the soil in your garden may be poorly drained. Grow chrysanthemums in raised beds or containers with drainage holes the following year.
Don't Use High-Nitrogen Fertilizers
Chrysanthemums suffering from overfertilization with high-nitrogen fertilizers may look healthy, but they don't flower. Nitrogen feeds only leafy growth in plants. To flower well, chrysanthemums need high-phosphorus fertilizers. Fertilizer labels show the amount of plant nutrients in a set of three numbers, such as 10-10-10. The first number shows the amount of nitrogen, and the second number shows the amount of phosphorus.
Fertilize chrysanthemums with a 15-30-15 fertilizer three times while the plants are actively growing. Dilute the fertilizer at a rate of 1 tablespoon per 1 gallon of water, and apply it to the ground around the chrysanthemums when the plants are 6 inches tall, 12 inches tall and when flower buds appear.