Knowledgebase
What are good onion companion plants? #132442
Asked June 06, 2013, 7:02 AM EDT
Norfolk County Massachusetts
Expert Response
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<personal data hidden> with more specifics on your onion problems and perhaps they can help you figure out what is wrong and what to do about it.
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.