Tomatoes are the crown jewel of vegetable gardens, celebrated for their taste and myriad uses. But even experienced gardeners can run into challenges growing perfect tomatoes! This comprehensive guide combines trusted advice from Stephanie Suesan Smith’s research and the latest findings from university and government resources to boost your tomato harvest and solve the most common tomato growing problems.
Starting Off Right: Choosing & Planting Tomato Transplants
Tomatoes thrive when they get what they want from the start:
- Site selection: Choose a location with at least 6–8 hours of direct sunlight and well-drained soil. Avoid planting where tomatoes, peppers, or other nightshade family crops grew in the last 2 years (crop rotation reduces soil-borne diseases) if possible.
- Transplants vs. seeds: Most home gardeners start with strong, disease-free transplants about 4–6 inches tall. For a wider selection, start seeds indoors 6–8 weeks before the last frost.
- Variety: Select disease-resistant varieties suited to your region (look for VFN on tags, which means resistance to Verticillium, Fusarium wilts, and Nematodes).
- Planting: Transplant after all danger of frost has passed. Bury stems deep enough that the bottom leaves are only an inch or two above the surface to encourage strong roots. Space plants 2–4 feet apart and rows 4–5 feet apart. Use raised beds in poorly drained soils. Water in well.
Top Tip:
Plant determinate (bush) tomatoes for concentrated harvests and indeterminate (vining) varieties for a longer picking season.
Ongoing Tomato Care: Water, Fertilizer, and Support
- Fertilizing: Mix a balanced fertilizer into the top 2-3 inches of soil before planting. Side dress with 1–2 tablespoons of fertilizer for tomatoes for each plant every 2–3 weeks beginning with fruit set.
- Watering: Deep, consistent watering is key! Drip irrigation or soaker hoses are best. Avoid wetting leaves; water early in the day to minimize fungal problems. Tomatoes need one inch of water a week (or one inch twice a week in hot climates).
- Mulching: Apply 2–3 inches of mulch (straw, wood chips) to maintain moisture and keep weeds down. This also helps prevent soil-borne disease splashing onto leaves.
- Supporting your plants: Cage or stake all tomatoes, especially indeterminate varieties, to improve airflow, ease harvest, and keep fruit off the ground.
Troubleshooting Tomato Problems
Even with the best care, tomatoes may struggle. Here’s how to recognize and solve common issues:
1. Blossom-End Rot
Symptoms: Large, black, leathery patch on the fruit’s blossom end.
Cause: Calcium deficiency and/or uneven watering—not a disease.
Fix: Maintain even soil moisture; avoid letting plants dry out, especially when fruit is forming. Don’t overfertilize with nitrogen. Lime acid soils if needed; test soil first for calcium levels.
2. Leaf Spots and Blights
- Septoria Leaf Spot: Small brown spots with tan centers, often on lower leaves.
- Early Blight: Concentric brown rings on older foliage.
- Late Blight: Water-soaked lesions with white fuzz beneath, rapid collapse of foliage.
Management:
- Remove affected leaves promptly.
- Water at the base; avoid wetting leaves.
- Space plants well for airflow.
- Rotate crops and destroy garden debris each winter.
- Mulch to reduce splashing.
- Fungicides can help but must be labeled for tomatoes; always follow instructions.
- Grow disease-resistant varieties where possible.
3. Wilts (Fusarium, Verticillium, Bacterial Wilt)
Symptoms: Leaves wilt and yellow, often one side first. No improvement after watering.
Fix: Remove and destroy infected plants. Rotate crops yearly. Select resistant varieties (‘V,’ ‘F,’ or ‘VF’ on the tag). Solarize the soil in severe cases.
4. Tomato Spotted Wilt Virus (TSWV)
Symptoms: Bronze or dark spots, purple leaf veins, stunting, cupping leaves, or spotted fruit
Cause: Spread by thrips, tiny insects carried from nearby weeds by the wind.
Management:
- Remove suspect plants.
- Control weeds around the garden, especially over winter.
- Use reflective mulch under plants (or silver-painted black plastic) to deter thrips.
- Plant resistant varieties where available.
- Insecticides are less effective; prompt removal of infected plants is best.
5. Pests (Hornworm, Aphids, Whiteflies, Stink Bugs)
- Hornworm: Large green caterpillars that quickly strip leaves and chew fruit. Handpick and drop in a jar of soapy water.
- Aphids/whiteflies: Small, sap-sucking insects on new growth. Control with a strong water spray, insecticidal soap, or natural predators.
- Stink bugs: Feed on fruit, causing pitting and deformity. Remove by hand; plant trap crops.
6. Fruit Cracking & Sunscald
- Prevention: Water evenly, mulch, pick fruit promptly once ripe, and provide shade during peak sun.
Harvesting and Enjoying Your Tomatoes
- Pick when fully colored for the best flavor.
- Ripen nearly mature fruit indoors if needed; store at room temperature, not in the fridge (once you cut the tomato, store in the fridge in a plastic bag).
- Use overripe tomatoes quickly.
- Save seeds from healthy heirloom plants at the end of the season (not from diseased plants).
Quick Reference: Tomato Problem Chart
| Problem | Symptom | Likely Cause | Fix/Prevention |
| Blossom-end rot | Black/dark patch | Ca/calcium, dry roots | Even water, soil test, avoid excessive N |
| Early/late blight | Leaf spots, wilting | Fungal spores | Remove leaves, fungicide, rotate crops |
| Fusarium/Vert wilt | Wilting, yellow | Soil fungus | Remove & destroy, plant resistant varieties |
| Spots on fruit | Sunken, dark | Anthracnose | Remove fruit, spray, timely picking |
| Yellow leaves, stunted | Virus, leafhopper | TSWV | Remove infected plant, use weed control, and plant resistant variety. |
Bonus: Tomato Growing FAQs
How can I prevent diseases?
Use crop rotation, mulch, disease-resistant varieties, clean up plant debris, avoid working wet plants, and water at the soil level early in the day.
What’s the best way to boost tomato flavor?
Consistent water, quality soil, and giving enough sun (at least 6–8 hours daily).
Do I need to prune tomatoes?
Remove suckers below the first flower cluster on indeterminate types for stronger growth and to limit disease.
Growing tomatoes is both art and science. With these practical, research-supported tips and troubleshooting advice, your harvest can be abundant and trouble-free. Ready to master tomatoes this season?
Download the tomato growing checklist.
If you have gardening questions, book a call or email me at stephanie@allaboutgardeningguides. I charge $25 for up to 15 minutes.
