This summer my several Acidanthera bulbs (which have flowered in past years) sent up many new shoots which grew to normal height. I had used a bulb fertilizer on them as they emerged from the ground. However, I only got one bloom from the entire lot.
Do you have any suggestions for getting them to bloom?
I’m either the best or the worst person to ask about Acidanthera, having planted 50 of them and lost them all within a year. I assumed it was because I did not dig up the corms and store them over the winter. According to The Brooklyn Botanic Garden’s Summer-Blooming Bulbs (edited by Beth Hanson; 2001), Acidanthera bicolor, also known as Gladiolus murielae (this is the preferred name) or Gladiolus callianthus, is hardy from Zone 7 and up, but won’t bloom after the first summer unless you pull up the corms, clean them, and let them dry. They should be stored over the winter in a dry place at 50 to 70 degrees. Pacific Bulb Society concurs, and adds that you may replant the corms after the last frost.
Other possibilities if you are already digging them up and replanting them after all danger of frost: Are your corms planted in a well-drained, sunny, wind-protected site? Did the fertilizer have a high proportion of nitrogen (this can cause a lot of leafy growth and no flowers)? You may find the following article from Portland garden writer Ketzel Levine of interest. Here is an excerpt:
“Clearly, you need this plant. The trick is growing it. In regions where winter temperatures are major league, plant acidantheras in April, then lift in fall and overwinter in paper bags. In more temperate regions, they should be hardy barring a catastrophic winter (read: 10 F). In the maritime Northwest, a greater challenge is preventing rot; the best advice I’ve heard is to top your already well-drained soil with several inches of sand or gravel and plant directly in that.”