Nicole's Quick Take: My go-to defense against whiteflies is planting marigolds, nasturtiums, and zinnias right alongside my vegetables, especially tomatoes, peppers, eggplants, and cucumbers. Marigolds release a compound that confuses whiteflies, nasturtiums act as a trap crop that lures them away, and zinnias bring in the beneficial insects that hunt whiteflies down.

By Nicole Johnsey Burke: Founder of Gardenary and Author of Kitchen Garden Revival

When The Spruce reached out this month asking how I keep whiteflies off my tomatoes, I gave them the same answer I'm about to give you (check out my featured article here).

I use this method across my whole vegetable garden: three specific companion plants, planted early, before the problem ever starts.

Signs Whiteflies Have Moved In: How to Identify Them

I once had a season where I'd brush past my plants, and a little cloud of tiny white bugs would lift off as if I had just disturbed a snow globe.

You’ll definitely notice a larger infestation, but if it’s still small, gently shake a plant and inspect the underside of the leaves. If a little puff of tiny white insects flutters up and flies around, you've got whiteflies. They actually resemble tiny moths more than flies, which trips up a lot of gardeners.

They tend to target nitrogen-hungry vegetables like tomatoes, peppers, eggplants, and cucumbers.

Evidence of Whiteflies:

• Tiny white insects that flutter up when you brush the leaves
• Yellowing, stunted growth on your plants
• A sticky residue (honeydew) that can turn into black sooty mold
• Fewer, smaller vegetables as the infestation progresses

They multiply fast in hot, humid weather, which is exactly when most of our gardens hit their stride. That's why I plant for prevention instead of waiting to react.

The 3 Companion Plants I Use Across My Vegetable Garden

Marigolds

My top pick, no contest. Some varieties release a compound called limonene that seems to confuse and repel whiteflies. I tuck them along the bed border or right between my vegetable plants, whether that's tomatoes, peppers, or eggplant. Bonus: they also draw in pollinators and predatory insects.

Nasturtiums

These release root compounds whiteflies avoid, and they double as a trap crop, pulling whiteflies and aphids away from your vegetables. I love how they spill over a raised bed edge while quietly doing their job.

Zinnias

Zinnias don't repel whiteflies directly. Instead, they attract the beneficial wasps that hunt whiteflies down for you. And you get gorgeous blooms all summer while it happens.

Quick tip: I keep a mixed flower and herb seed set on hand so I always have marigold, nasturtium, and zinnia seeds ready the moment I'm planting a new bed. Planning ahead beats scrambling once you've already spotted a problem.

If Whiteflies Are Already There

Companion planting alone won't fix an active infestation.

Start here, least invasive first:

1. Spray the undersides of leaves with water to knock off eggs and nymphs.
2. Add yellow sticky traps nearby to catch adults.
3. Use an insecticidal soap spray every four to five days for about two weeks if needed.

I never reach for synthetic pesticides in my vegetable garden. They kill off the beneficial insects your zinnias just worked to attract, right along with the pests.

My Organic Pest Control Course walks through this same least invasive approach for every common pest in a kitchen garden. And for a deeper dive on tomatoes specifically, see 10 Ways to Naturally Protect Tomatoes from Pests.

Common Mistakes

• Planting flowers too far from the vegetables. They only work if they're actually close enough to interact.
• Waiting until the infestation is bad. These plants are prevention, not rescue. Plant them alongside your vegetables from the start.
• Expecting companion planting to solve a serious infestation alone. Pair it with the treatment steps above once whiteflies show up.
• Skipping the beneficial insect piece. Zinnias matter just as much as the plants that repel pests directly.