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

Tomato Troubleshooting

I've grown tomatoes in Houston heat, Chicago cold, and Nashville humidity. And I'll tell you the truth: tomatoes are dramatic. They will absolutely let you know when something is wrong. Once you know what to look for, most problems are very fixable.

Here's your quick-reference guide to diagnosing the seven most common tomato problems and getting your plants back on track!

1. Pest Damage

What it looks like:

Holes in leaves, chewed stems, missing fruit, sticky residue, or tiny bugs visible on the undersides of leaves.

Common culprits:

• Tomato hornworms — large green caterpillars that can strip a plant overnight
• Aphids — tiny clusters (usually on new growth or stem undersides) that weaken plants fast
• Flea beetles — small jumping insects that leave peppered holes in leaves

Organic fix:

• Hand-pick hornworms and drop them in soapy water
• Blast aphids off with a strong stream of water
• Use row covers early in the season to keep flea beetles off young plants
• Plant basil, marigolds, or nasturtiums nearby as natural pest deterrents

Need help identifying a pest or more ideas for a solution?

Check out our free pest control ebook!

2. Disease (Blight, Wilt, Mold)

What it looks like:

Brown or black spots on leaves, yellowing that spreads fast, wilting despite good watering, or white powdery coating on leaves.

Common culprits:

• Early blight or late blight (fungal)
• Fusarium or verticillium wilt
• Powdery mildew

Organic fix:

• Remove affected leaves immediately and don't compost them
• Water at the base of the plant, never overhead — wet foliage invites fungal problems
• Rotate where you plant tomatoes each season to break disease cycles
• Choose disease-resistant varieties next year (look for letters like VFN on seed packets)

3. Not Enough Sun

What it looks like:

Leggy, stretched plants; pale green or yellowish leaves; flowers that drop before setting fruit; weak overall growth.

The fix:

Tomatoes need a minimum of 6 hours of direct sun daily — 8 hours is ideal. If your plants are struggling in a shadier spot, this may be your answer. There's no workaround for lack of light. Move containers into a sunnier location, or plan to relocate that raised bed next season.

4. Nutrient Deficiencies

What it looks like:

Yellow leaves (especially older, lower ones), purple-tinged stems or undersides of leaves, poor fruit development, blossom end rot.

Common deficiencies:

• Nitrogen — overall yellowing, slow growth
• Calcium — blossom end rot (dark, sunken spot on the bottom of fruit)
• Magnesium — yellowing between leaf veins on older leaves

Organic fix:

• Start with great soil. This is the foundation everything else builds on. I use a high-quality organic mix in all the raised beds I build.
• Top-dress with worm castings or compost mid-season
• For blossom end rot specifically, the issue is usually inconsistent watering preventing calcium uptake — not a calcium-deficient soil

5. Watering Problems

What it looks like:

Wilting (overwatering AND underwatering both cause this), cracked or split fruit, blossom end rot, root rot.

The fix:

• Water deeply and consistently — tomatoes hate fluctuating moisture levels
• Aim for about 1 to 2 inches of water per week, more in intense heat
• Always water at the base, not overhead
• Let the top inch of soil dry out slightly between waterings, but never let plants fully wilt
• Cracked or split tomatoes almost always point to inconsistent watering after a dry spell followed by heavy rain or irrigation

6. Temperature Stress

What it looks like:

Blossoms dropping without setting fruit, poor fruit set even on a healthy-looking plant.

The fix:

Tomatoes stop setting fruit when temperatures go above 85°F at night or below 55°F. This is especially common in early spring and in the peak of summer in hot climates.

• Don't panic — the plant usually recovers when temperatures moderate
• In extreme heat, use shade cloth during the hottest part of the day
• In cool springs, wait to plant until nighttime temps are consistently above 55°F

7. Lack of Support

What it looks like:

Bent or broken stems, fruit sitting on the soil, the whole plant flopping over.

The fix:

All you need is a sturdy trellis. I prefer metal trellises because they last for years and are strong enough to hold the weight of tomatoes. Indeterminate tomatoes can reach 6, 8, even 10 feet tall. They need real support from the beginning.

• Use a sturdy trellis system that can handle the full size of the plant
• Tie stems loosely with soft garden twine as the plant grows
• The Nicole Arch Trellis was designed specifically for this — it's the support structure I use in my own Nashville garden, and it consistently sells out for a reason

FAQ: Tomato Troubleshooting

Why are my tomato leaves turning yellow?

Yellow leaves on tomatoes can signal nitrogen deficiency, overwatering, disease, or natural leaf drop on lower leaves. Start by checking your watering consistency and soil quality before assuming a nutrient problem.

Why are my tomato flowers falling off without producing fruit?

Blossom drop is almost always caused by temperature extremes — either too hot (above 85°F at night) or too cool (below 55°F). Inconsistent watering and lack of pollinator activity can also contribute.

What is blossom end rot and how do I fix it?

Blossom end rot is a dark, sunken spot on the bottom of tomato fruit caused by calcium deficiency at the cellular level. The most common cause is inconsistent watering, which prevents the plant from taking up calcium even when it's present in the soil. Water deeply and consistently to fix it.

How do I get rid of tomato hornworms organically?

Hand-pick them from plants and drop them in soapy water. If you see white egg sacs on a hornworm's back, leave it — those are parasitic wasp eggs that will naturally control the hornworm population.

Why does my tomato plant look healthy but produce no fruit?

This is usually a pollination issue or temperature problem. Make sure your garden has pollinators present, consider gently shaking the flowers to help pollination along, and check that nighttime temperatures are in the right range for fruit set.

Where can I get a trellis system strong enough for tomatoes?

The Nicole Arch Trellis from Gardenary is built specifically for heavy-producing fruits and vegetables. It's one of the best metal trellises for durability and beauty.