Every summer, the garden forums and groups are full of gardeners cursing the dreaded tomato hornworm. So many organic gardeners are quick to kill or torture them, but we'd like to offer some alternate solutions to consider.
1. Relocate them. You can easily relocate tomato hornworms to other nightshades and plants that you aren’t planning to eat. Datura, devil's claw, and wild ground cherries are good candidates for hornworm relocation, and you could also consider growing a sacrificial tomato plant.
Our hornworm relocation plant of choice is datura (aka moonflower) because it's a hardy, drought-tolerant plant that grows well in our landscape and can handle a good pruning by the time tomato hornworms make their appearance. It's also a perfect choice because this plant's gorgeous night-blooming flowers are beloved by the sphinx moth (aka hawk moth or hummingbird moth), which are beautiful, beneficial nighttime pollinators and what tomato hornworms turn into if they're allowed to live. We think any creature who will happily munch toxic datura and stinky devil’s claw leaves, then zip around drinking hallucinogenic flower nectar like a weird blissed out fairy deserves some respect. It's truly a magical sight to see and a win-win situation for everyone.🐛✨
2. Do Nothing and Observe. We’ve noticed that the hornworms come out in abundance in the heat of the summer when our tomato plants have gotten gangly and unmanageable, so another option is to just let the hornworms help you do the pruning you’d be doing anyway, keep observing, then relocate them if they become an issue. At this point in the summer tomato plants don’t produce much because it’s just too hot, so we usually prune our plants heavily and try to get them through the summer months to produce again in the fall or we start fresh with a new batch of tomato plants. It could be that the hornworms are showing up just in time to help in this clearing process, so maybe just embrace it.
3. Try Companion Planting. Some people have had luck growing certain plants near their tomatoes and peppers to deter the sphinx moth from laying her eggs. Some of the plants known to help with this are basil, borage, nasturtium, marigold, dill, and chamomile.
Hornworms and Sphinx moths
Here are some pictures of hornworms from around our garden.
Hornworms on tomato plants:
Hornworm poops (they're quite large and look like mini grenades). If you don't notice hornworms on your plants right away because of their camouflaged coloring and you don't notice that they've started chewing your plants down to nubs, you might notice this clue that a hornworm is nearby.