Tomatoes are one of the most popular plants in home gardens and one of the most rewarding. They are also prone to a handful of common problems that can reduce harvests or ruin fruit. The good news is that most of these problems trace back to a few avoidable mistakes.
This guide covers the most common tomato growing mistakes and how to fix or prevent each one.
Mistake 1: Planting Too Early
Tomatoes are warm-season plants and are damaged by frost. Cold soil and nights also slow their growth. Planting too early often leads to stunted plants that take weeks to recover.
What to Do Instead
- Wait until after your area’s average last frost date.
- Many gardeners wait until nighttime temperatures stay reliably above about 50°F.
- Harden off transplants by gradually exposing them to outdoor conditions over about a week.
- If you plant early, protect plants with row covers or wall-of-water protectors.
Mistake 2: Not Enough Sun
Tomatoes need full sun to produce well. Most sources recommend at least six to eight hours of direct sun each day. In too much shade, plants become leggy and produce few fruits.
What to Do Instead
- Plant in the sunniest spot available.
- If your yard is shady, try containers you can move into sun, or choose smaller cherry varieties, which may perform better in partial sun.
Mistake 3: Planting Too Close Together
Crowded plants compete for light, water and nutrients, and poor air circulation encourages disease.
What to Do Instead
- Follow spacing on the seed packet or plant tag. Indeterminate varieties generally need more space than determinate ones.
- Leave room for air to move between plants.
- In raised beds, plan where tomatoes go before planting other crops. See our raised bed plans.
Mistake 4: Planting Too Shallow
Tomato stems can grow roots along the buried portion. Many gardeners plant transplants deeper than they were in their pots to grow a stronger root system.
What to Do Instead
- Remove lower leaves and bury part of the stem, leaving the top set of leaves above ground.
- Alternatively, dig a shallow trench and lay the stem sideways, gently bending the top upward.
Mistake 5: Inconsistent Watering
Uneven watering, such as letting soil dry out and then soaking it, is linked to problems like blossom end rot and fruit cracking.
What to Do Instead
- Water deeply and consistently, aiming to keep soil evenly moist but not waterlogged.
- Water at the base of plants rather than on the leaves.
- Use mulch to keep soil moisture steady.
- Consider drip irrigation or soaker hoses.
Mistake 6: Ignoring Blossom End Rot
Blossom end rot appears as a dark, sunken spot on the bottom of fruits. It is associated with calcium not reaching developing fruit, often because of uneven watering rather than a lack of calcium in the soil.
What to Do Instead
- Keep watering consistent.
- Mulch to reduce moisture swings.
- Test your soil before adding calcium. Many soils already have enough. See how to test and improve garden soil.
- Remove affected fruit. Later fruit often develops normally once watering evens out.
Mistake 7: Over-Fertilizing With Nitrogen
Too much nitrogen can produce lush leaves but fewer flowers and fruits.
What to Do Instead
- Start with compost and a soil test.
- Use a fertilizer formulated for tomatoes or vegetables and follow the label.
- Avoid heavy nitrogen feeding once plants begin flowering.
Mistake 8: Not Supporting Plants Early
Tomatoes, especially indeterminate varieties, can grow large and heavy. Supports added late can damage roots and stems.
What to Do Instead
- Install cages, stakes or trellises at planting time.
- Choose sturdy, tall cages for large varieties. Many small store-bought cages are too short for indeterminate plants.
- Tie stems loosely with soft ties as they grow.
Mistake 9: Choosing the Wrong Variety
Not every tomato suits every garden.
What to Do Instead
- Determinate varieties grow to a set size and ripen fruit over a shorter period. They are often good for containers and canning.
- Indeterminate varieties keep growing and producing until frost. They need more space and support.
- Look for disease-resistant varieties. Codes on seed packets or tags, such as V, F and N, indicate resistance to certain diseases or pests.
- In short-season areas, choose varieties with fewer days to maturity.
Mistake 10: Ignoring Disease Prevention
Fungal diseases like early blight and septoria leaf spot are common in many regions, especially in humid weather.
What to Do Instead
- Space plants for airflow.
- Water at the base and avoid wetting leaves.
- Mulch to reduce soil splashing onto lower leaves.
- Remove lower leaves that touch the soil.
- Remove and dispose of badly infected leaves. Many gardeners avoid composting diseased material in home piles.
- Rotate tomatoes and related crops (peppers, eggplant, potatoes) to a different spot each year when possible.
- Contact your local cooperative extension service to identify specific diseases.
Mistake 11: Over-Pruning or Never Pruning
Pruning is a matter of preference and variety. Removing all foliage can expose fruit to sunscald, while never pruning large indeterminate plants can lead to a tangled mass.
What to Do Instead
- Determinate varieties usually need little pruning.
- For indeterminate varieties, many gardeners remove some suckers (shoots between the main stem and branches) to manage size.
- Keep enough leaves to shade fruit.
Mistake 12: Harvesting at the Wrong Time
Leaving fully ripe fruit on the vine can lead to cracking, pests and overripe tomatoes.
What to Do Instead
- Harvest when fruit has reached full color for the variety and gives slightly to gentle pressure.
- In very hot weather or before heavy rain, some gardeners pick tomatoes as they begin to color and let them finish ripening indoors at room temperature.
- Store ripe tomatoes at room temperature for the best flavor.
Frequently Asked Questions
Why are my tomato flowers falling off?
Blossom drop is often associated with temperatures that are too hot or too cold, as well as stress from drought or excess nitrogen. It often resolves when conditions improve.
Why are my tomatoes cracking?
Cracking is commonly associated with sudden changes in water, such as heavy rain after dry weather. Consistent watering and mulch can help.
How often should I water tomatoes?
It depends on weather, soil and container size. Check soil moisture a couple of inches down and water when it starts to dry. Containers often need daily watering in hot weather.
Should I remove yellow leaves?
Yellowing lower leaves are common as plants age. Removing them can improve airflow, but persistent yellowing may indicate disease or nutrient problems.
Can I grow tomatoes in containers?
Yes. Choose large containers, a quality potting mix and compact varieties, and water often.
The Bottom Line
Most tomato problems come from planting too early, crowding, uneven watering, too much nitrogen, weak support and poor disease prevention. Give your plants full sun, steady moisture, mulch, strong supports and good airflow, and choose varieties that suit your space and climate. Your harvest will thank you.
Editorial note: Backyard Bloomer is independent and reader-supported. This guide is based on research into manufacturer documentation, published specifications and widely accepted best practices; we have not been paid to mention any product. If we add affiliate links in the future, they will be clearly disclosed per our Affiliate Disclosure.