The Q&A Archives: Brown Gladiolus Buds

Question: I have planted a number of gladiolus bulbs in a cutting garden for several years. Last year, the buds wilted and turned brown before fully opening. I had very few good blooms. I blamed the problem on using a treflan herbicide on my gladiolus bed. This year, I planted new bulbs in approximately the same area and did not use any herbicide. They are just beginning to bud, and seem to have the same problem. It this a disease, need for additional fertilizer, . . .? I love glads and don't want to stop growing them!

Answer: It may be that your glads are infested with thrips. These tiny insects feed by sucking liquids out of the tissues. Affected flower buds shrivel and dry up. Female thrips can lay up to 200 eggs and only 2-4 weeks are required for them to reach maturity, so there can be as many as 5-6 generations in a single growing season. Unfortunately, once the thrips are in the flowers, it's very hard to control them. In greenhouse situations, high humidity leads to increased thrips mortality because it fosters a fungus that attacks the insects. You can try keeping your soil more moist than usual to kill the pupating stage in the soil. You can purchase predatory mites, lady beetles and lacewings and release them, as they all feed on thrips. Beneficial nematodes also feed on the pupae in the soil. Gardens Alive carries all these creatures -- call them at 812-537-8650 or send an email to

Next spring you can try to prevent their presence with reflective mulch of aluminum foil. Studies show that the reflected light confuses the thrips that migrate from surrounding areas, and prevent them from landing on plants which the foil surrounds. I wish you the best of luck!

« Click to go to the homepage

» Ask a question of your own

Q&A Library Searching Tips

  • When singular and plural spellings differ, as in peony and peonies, try both.
  • Search terms are not case sensitive.

Today's site banner is by ge1836 and is called "Sempervivum Henry Carrevon"