Bulbs Won't Bloom

Question:

Leaves yes, flowers no. Why don't my irises bloom? I have planted well over 35 bulbs in the last few years. Since we don't get a good freeze here, I stored the bulbs in the fridge for a few weeks before planting. They get plenty of water, and have a nice southern exposure. The oldest bulbs come up about February, grow slowly, then die with no flowering. I planted some daffodils this year, and they have spindly stalks and no flowers.

The irises that were planted decades ago in the backyard do blossom most years, but haven't flowered yet. Should I fertilize them in the winter? Why don't they bloom? We did have a few days under 40 degrees over Christmas, and other places I've lived in L.A. have blossomed like mad! We're at 1800 feet here, with rather acidic soil and very alkaline water. Help?

Hardiness Zone: 10a

Brandy from Los Angeles, CA

Answer:

Hi Brandy,

Here are some ideas:

Soil Fertility

Because your daffodils are also failing to bloom, I suspect you may have a problem with your soil. You mentioned having slightly acidic soil and very alkaline water, but you didn't mentioned what type of irises you're growing. Although most irises are pH tolerant, some perform prefer slightly acidic soil, while others prefer a neutral to slightly alkaline soil. Just to be safe, I would recommend getting a soil test done.

Your county extension agency can give you more information. Tests usually only cost around $15 and the results will tell you exactly what you need to add (if anything) to correct soil problems-including problems with pH and fertility. For example, test results may recommend adding sulfur to lower the pH of your soil, or recommend adding limestone to raise it.

Your soil may also lack sufficient organic nutrients. Irises can be heavy feeders, and they don't like to compete with nearby grass, weeds, or other iris rhizomes for nutrients. A light application of fertilizer in the spring and again 4 weeks after blooming is usually more than sufficient. It is also best to avoid fertilizers high in nitrogen. Again, a soil test will provide you with specific recommendations.

Planting Depth and Spacing

Iris rhizomes prefer to sit near the top of the soil with only their roots buried below the surface. They also like to have some breathing room, and should be divided every 3-4 years when they become overcrowded. Here is a great bulletin from the UC Davis Extension Agency on growing all types of Irises.

• http://ucce.ucdavis.edu/files/filelibrary/1808/11935.pdf

Good luck!

Ellen

About The Author: Ellen Brown is an environmental writer and photographer and the owner of Sustainable Media, an environmental media company that specializes in helping businesses and organizations promote eco-friendly products and services. Contact her on the web at http://www.sustainable-media.com

Answers:

Bulbs Won't Bloom

As soon as leaves appear in the spring, add a 20-20-20 fertilizer. (05/31/2008)

By Angie