What are good onion companion plants?

Asked June 6, 2013, 7:02 AM EDT

What can I do to prevent bulb damage on onions in an organic garden? What are good companion plants? Would marigolds help? Thank you

Norfolk County Massachusetts

4 Responses

Hi,
Without a little more specific information I am not sure what information you are looking for. Are the bulbs being attacked by an insect or eaten by an animal or are the plants infected with a disease that is causing bulb failure? I have occasionally noticed damage to onion foliage but not to the bulbs in my MA garden. Onions seem to enjoy light, sandy soils in full sun, moderate fertility (don't overapply compost) and need to be free from competition from weeds. As a general rule of thumb in organic gardens, one would want to interplant crops with flowers, herbs and other vegetables to break up any monocultural tendencies which makes it harder for insects to find their host plant. This is actually a good idea in any garden. Probably one would not want to interplant between bulbs as it is good if there is adequate air circulation around them. One could plant onions in patches with other plants between them. Companions can include beets, chard, peppers, chamomile. Mind you, there really is not consistent scientifically proven results that companion planting will reduce insect damage but theoretically it might work. So these are some plants you could consider interplanting or alternate planting your onions with if they are experiencing insect troubles. If it is a disease or animal problem, companion planting will likely not make any different. You can call the UConn Home & Garden Education Center at (860) 486-6271 with more specifics on your onion problems and perhaps they can help you figure out what is wrong and what to do about it.

I should have been more clear. I don't have damage yet & want to be proactive in my organic garden. I have yellow& red onion sets that I planted. They look fine, however my early radishes were being bothered by worms of some sort & I'm afraid they will get the onions too. This is the 1st time my radishes are being eaten, so I'm not sure what to do about other root crops. I've planted carrots too & beets, so am I in trouble? Or will this worm become a bug & fly off now that it's June? That would be a blessing. Thank you for your help, I appreciate it. Kathleen

Hi,
The insects in your radishes are probably cabbage maggots which are the larvae of a small fly that attacks members of the cabbage family. There is a different onion maggot fly and carrot rust fly. Although they do similar damage, I don't think the cabbage maggot fly would lay eggs on onions or carrots. Beets don't seem to get maggots; instead they get leaf miners and some diseases. If you really want to protect your onions you could cover them with a floating row cover.Any of the root crops can be grown under a row cover. I like to plant a few groups of these plants throughout the garden so that amid all the other flowers and vegetables, some are likely to remain unaffected.

thank you that's great advice! I will plant my root crops around the garden, instead of grouping them. Thanks again! Kathleen