Fighting Nematodes and Soil Pests

Before you panic about nematodes, consider this: Most tomato problems come from poor soil conditions, not pests. Someone mentions nematodes and suddenly that's the diagnosis. Let's figure out what you're actually dealing with.

What Are Nematodes?

There are good nematodes and bad nematodes. Root knot nematodes are the bad ones—microscopic pests living in soil that feed inside tomato roots, disrupting water and nutrient flow.

Signs of root knot nematodes include stunted growth and yellowish plants. But those symptoms also show up with poor watering, bad soil, or nutrient deficiencies.

How to Know for Sure

Once you've given up on your tomato plant, dig it up and examine the roots. Look for knots and bumps. That's nematode damage. No knots? You don't have nematodes—you have a different problem.

If You Really Have Nematodes

For containers: Use minimum 20-gallon containers with fresh, high-quality potting soil (sphagnum peat moss or peat moss as the first ingredient). You can place your container right on top of the old nematode-infested soil—the new soil creates a barrier.

For backyard soil: Dig a hole 2 feet wide and 2 feet deep. Throw away the soil—it contains the nematodes. Fill the hole with quality potting soil and plant your tomato. See our backyard planting guide for details.

If nematodes return in backyard soil, switch to container gardening.

Prevention

Nematodes attack weak, water-stressed plants. Use good potting soil and keep roots consistently moist. Frequent irrigation reduces nematode damage.

You'll read articles recommending crop rotation—don't plant in the same spot every year. That's impractical for most home gardeners. The simple fix: Use quality potting soil as we've discussed. If you suspect disease later, replace with fresh soil.

The Real Solution

Most nematode problems disappear when you use proper potting soil with good water retention. Strong, healthy plants resist pests naturally. Start with the right foundation—everything else gets easier.

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Next Steps

Choose the right potting soil →
Master proper watering →
Learn the fundamentals →

Dave Freed / The Tomato Guy