The Q&A Archives: Brown Spots On Tomatoes

Question: This is my first year to plant a garden, so I am still alittle "green" on recognizing things. I planted big boy tomatoes that were doing well but I noticed now that they are beginning to get large brown spots on the bottom of them and developing big creases in their skin. I have consulted local garden stores for advice to no avail. The plants are also beginning to yellow at the base. They have not been overwatered and receive plenty of sun. Any thoughts?

Answer: This has been a cool cloudy and wet season and many people are having trouble with their tomatoes.

Odd shaped tomatoes are often caused by pollination problems, and tend to be more common in wet years.

A single black spot on the end opposite the stem is usually "Blossom End Rot" and it affects tomatoes, peppers, and some other plants. It is technically attributed to calcium deficiency in the soil, but it often appears in cases of fluctuating soil moisture levels.

Remedies include adding organic matter to the soil to increase its moisture holding capacity, keeping the plants evenly moist, using a mulch, and in some cases spraying plants with a blossom end rot spray (contains calcium) which can usually be purchased from your local garden center. Usually, more attention to keeping the soil evenly moist (but not soggy) will solve the problem. You might want to dig down into the soil a bit and see how effective your watering actually is and how well your soil actually holds moisture.

Since yours is a new garden, you might want to pay particular attention to running basic soil tests such as checking the soil pH and adding organic matter to it to prepare the soil better for next year.

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