TheGardenLady received this question from Joyce.

I love marigolds but am unable to keep them healthy. I have had the same problem in the past and gave up on them for a while. Now several years later the problem still persists. The foliage looks fine but the flowers and buds (all stages) are full of worms. They are about 1/8-1/4 inch size, vary from brown to beige in color and leave behind a sawdust-like residue on the flower. They burrow into the seed pod and even flowers that look unaffected have the critters inside. None of my other annuals are affected. They are all grown in containers on a balcony. Any thoughts and any treatment suggested would be welcome.

Marigolds, Latin name Tagetes, are usually one of the easiest annual flowers to raise because they have so few pest problems. In fact, they are often used to prevent problems for other plants because they get rid of nematodes in the soil. They are used as companion plants.   See here.  

But like most plants, Marigolds like to have their environment just as it was in their place of origin. Marigolds, in spite of some of their names, originated in Mexico and Central America. There they had lots of sun and not too rich soil. Marigolds, if raised in an area where they do not get the conditions they want are more susceptible to problems.  See here.

Remember that the best method of reducing insect and/or disease problems is to keep the plants growing vigorously and free from stress. There are certain cultural practices that should help to reduce insect and disease problems: (1) select a planting site which provides desirable growing conditions for a particular annual - your balcony might not be the best location for marigolds; (2) if they are on your balcony, avoid planting in corners where light intensity and air circulation are minimal; (3) keep marigolds growing vigorously by placing them in the sun, not using too much fertilizer and not too much irrigation- they like dryness.(4) avoid allowing them to wilt since water-stressed plants are more susceptible to infestation by thrips and red spider mites; (5) remove dead flowers from marigold plants which do not naturally fall from the plant; (6) prevent pathogenic fungal spores from germinating by watering early in the morning and keeping water off plants as much as possible (7)provide good air circulation around plants by allowing ample space between plants; and (8) remove weeds from flower beds and monitor annuals frequently since they are host to insects and/or disease organisms.  See here.

There are slugs, snails and insects that do attack marigolds. Though you describe worms, TheGardenLady suspects that your marigolds are being eaten by earwigs which are not worms. The below website has a photo of the damage earwigs do to marigolds.

In the future, any reader who has  a problem is advised to send in a photo with a close-up of the problem and a description of the location the plant is in. This will help  TheGardenLady enormously in diagnosing.

Joyce, if TheGardenLady is incorrect on this diagnosis of earwigs, please send a good, clear photo of the problem with a photo of your “garden site.” TheGardenLady will be happy to continue researching your problem.

This website has problems of marigolds. 

For this summer, though there are methods of treating earwigs, if that is what your plant has,  TheGardenLady suggests that you toss out the marigolds you have with the problem. (They are cheap plants not worth the time and effort of trying to salvage them.) Buy some new marigolds or start them yourself. Use average to poor soil - soil from outdoors is perfect- to pot the marigolds and give them ample soil for their roots to grow in. Do NOT use fertilizer enriched potting soil for marigolds. Put the marigolds in their pots in FULL sun. Do not mulch the marigolds. Do not keep the marigold pots damp. Let marigold soil dry out between waterings- but do water regularly; don’t let the plants wilt. Pinch off any dead or dying parts- leaves, seed pods and flowers.

Please let TheGardenLady know if her advice helped.  A photo would be welcomed.

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