One of the prime tenets of effective organic gardening is companion planting. When carefully planned, this process can protect certain species from specific pests.
One way to do this is to offer a trap crop that the pest loves more than your main crop, something you can sacrifice for the greater good. Planting the herb dill near tomatoes is a good example, because tomato hornworms will attack the dill over the tomatoes. You can then pick the hornworms off the dill as they appear. If you’re careful, you may be able to save the dill; but even if you don’t, you’ve kept a nasty critter away from your tomatoes.
Here’s a great Companion Planting Chart from North Carolina State University Extension.
Want to learn more about companion planting?
We’ve got you covered with a lot more information on companion planting for your home garden. Check out these in depth guides to companion planting:
How to Use Companion Planting In Organic Gardens
Almanac.com writes about Dealing with Tomato Hornworms
University of Minnesota Extension on Tomato Hornworms in Home Gardens
Beatriz Moisset says
Will you kindly supply references about tomato hornworms feeding on dill? As far as I know, tobacco and tomato hornworms feed almost exclusively on Solanaceae, that is members of the tomato, potato family. They also use some mustards as hostplants. But I have never heard of them feeding on dill.
See the Hostplant Database: http://www.nhm.ac.uk/our-science/data/hostplants/search/list.dsml?searchPageURL=index.dsml&Familyqtype=starts+with&Family=&PFamilyqtype=starts+with&PFamily=&Genusqtype=starts+with&Genus=Manduca&PGenusqtype=starts+with&PGenus=&Speciesqtype=starts+with&Species=sexta&PSpeciesqtype=starts+with&PSpecies=&Country=&sort=Family
Rob Maxwell says
Ditto. I grow dill all over my garden because the tiny flowers attract the parasitic and parasitoid wasps that lay there eggs on various caterpillars.
Wanda Brown says
I have dill growing with my tomatoes but the hornworm preferred the tomatoes. Now the black swallowtails love the dill and those caterpillars have wiped it out.
Beatriz Moisset says
So much for companion planting: The myth of companion planting. By Laura Pottorff, Colorado State University Cooperative Extension, Horticulture/Pathology
Debbie Fedie says
There is no authoritative (educational, University Extension, etc.) based evidence that tomato hornworms or tobacco hornworms feed on dill. Both these types of caterpillars feed on members of the Solanaceae or nightshade family. Dill, as well as any other member of the carrot family, will not attract or feed these caterpillars, nor will it deter them. Datura inoxia (Moonflower), a member of the nightshade family, will attract them and act as a trap plant, feeding the parent moths with nectar and the caterpillars as well, keeping them from ever settling on tomato or other crop plants. I can say with absolute certainty this works because I have done it for several years. The caterpillars most commonly found on dill, parsley, rue, and other plants in the carrot family are swallowtails, not hornworms. Please verify sources before publishing such blatant inaccuracies. I will be surprised if I receive a reply since other have commented negatively about this article and it has not been corrected or removed. By the way, I am a Master Gardener and have gardened many years and speak from experience and education.
Debbie Duggan says
Thank you, Debbie Fedie, for this info. I have been confused about dill because of conflicting info out there. Question: Do you plant the moonflower near tomatoes, or a good distance away?
Don’t know if it’s true or not, just happen to run across this article. But here’s a reply…your just blatantly RUDE Debbie Fedie!!
Tracy Frahm says
Gina, I think she stated the facts rather well and provided a service to us by providing information based on years of experience. Kudos to her for piping up and refuting false information.
Yes, I would. rather receive information from a Master Gardener such as Debbie than read unproven methods. Thank you Debbie for helping other gardeners. I just found one horn wood his morning checking on my tomatoes, and oh Boy, it was devastating. I sincerely am grateful for your intelligent and professional advice.
I noticed something growing in my flower gardens last summer… It was a volunteer moonflower plant that I have never seen before… I was told it was huge ( i have photos).
Approximately 4 to 6 feet away from this huge plant or my tomato plants. We spent a lot of the summer removing hornworms from the tomato plants… One tomato plant had most of its leaves eaten!!
I’m not a master gardener… I love to grow anything.
I have several moonflower (and have for years) and the worms last year ate the moonflowers AND the tomatoes. The moonflower did not keep them from the tomato at all it was just a secondary food source.
Debbie Fedie says
My moonflowers (Datura inoxia) were always 20 feet or more away from the tomato plants. They can become rather large plants so I never planted them with my veggies. I liked to have them closer to my patio to make it easier to watch the hummingbird moths as they visited the blooms in the evening when they opened. The moths are the parents of the hornworms that feed on tomato plants. While visiting the moonflowers the moths will lay their eggs on the plants where the young will later feed on the leaves. Since the adult moths prefer the nectar of the moonflower blooms over tomatoes and the caterpillars use the leaves as a food source it is very easy to satisfy them and keep them off your tomatoes.
Thanks for this.
Thank you Debbie Fedie
In my experience, planting marigolds around my tomatoes works VERY well. Just make sure you select a variety that blooms on the summer, when your tomato plants are growing and need the protection. Last year I got a variety that bloomed near the fall, so wasn’t effective. In years that I have forgotten the marigolds, I have hornworms. When I plant marigolds, I do not have issues. I feed the dying blooms to my chickens too.
And dill can spread like crazy. I don’t want it taking over my garden, so I like the marigolds.
Lisa G says
I have had the same success with marigolds. I started veggie companion planting 30 years ago. The first year I experienced horn worms on tomatoes. Research suggested marigolds to repel which I prefer to sacrificing another plant. In all of these years I have never had another hornworm and marigolds are very easy and reliable.
How many marigolds should be planted ? … one beside each plant?
Thank you Bobbi for sharing this! I will definitely try the Marigolds.
Kelli Umbstaetter says
Thank you for this information. I had a problem with hornworms last year. Luckily I was able to save my tomatoes but they wiped out my banana peppers. I will definitely try planting moonflowers.
Dee harrison says
Get a blacklight flashlight for about $10. Go out after dark and the caterpillars will glow in the dark. Pick them off and drop in water, then feed them to your chickens in the morning
Cheryl G Tuttle says
All you need to do is plant basil and marigolds . I have done this for years with great success. I plant them with my tomatoes every year. See Carrots Love Tomatoes.
The simple best way to control tomato worms is get them when young and kill them
Albuquerque New Mexico