Why do irises not bloom

Here is a list of some of the more common culprits: Planting in too much shade. They need at least 6 hours of full sun per day. Over feeding with animal manure or fertilizer high in Nitrogen. We recommend a low-Nitrogen fertilizer, such as a mix. No feeding at all. Many thanks. There are several things that can cause this problem. The plants may be too crowded. As the irises grow, the clump begins to crowd itself and must be divided.

Another possibility is that the surrounding landscape trees and shrubs may have grown and begun shading the irises. Fertilization with a fertilizer high in nitrogen will stimulate vegetative non-flowering growth rather than flowers. Lack of water in late winter and early spring may also prevent proper growth. To remedy the problem, determine which of the scenarios described above is most likely to fit your situation. You can get a soil tester from any hardware store.

Check the nitrogen and pH of your soil. The PH should be 6. Make sure your soil is set up properly to feed your plants. Fertilize irises in early summer if your soil needs extra nutrients. Your iris should not need constant fertilization unless your soil is low in nutrients. There is a chance that a late freeze in your area caused your bulbs to freeze or become dormant. If the freeze happens before the bulb is established then the iris may go dormant for the year.

Allow your iris time to establish itself before giving up on it. The best fertilizer for your irises is a low nitrogen fertilizer at a split. Most common garden fertilizers will work. You can also use bone meal as a fertilizer on irises. I place the fertilizer around the bulb or rhizome, not on it.

It is best to fertilize your plants a month before you expect them to start blooming. Keep mulch away from the tops of the rhizomes. Look at the size of the rhizome when you plant it; if it is small, it is possibly a young rhizome that needs to grow for a year or two to reach maturity before it is able to flower. Irises that are too closely planted may not bloom. When putting in new iris rhizomes, place them at 12 to 24 inches apart. Place the end of the rhizome bearing the fan of leaves so that it faces into an empty spot in the bed because the iris will increase its growth in this direction.

This gives the plants room to grow over the next two to three years. After two to four years, the irises become crowded from new growth and can stop blooming.

Dig up the clumps and divide them.