There’s nothing like the excitement of planting tomatoes in the garden, watching them grow, and dreaming about that first juicy slice for salads and sandwiches. But then, just as the first fruits start to ripen, I notice something alarming. The bottoms of a few tomatoes have turned dark, sunken, and leathery, almost like they’re rotting right on the vine. It’s frustrating—after all this effort, why is this happening? I’ve heard people say adding Tums to the soil can fix it, but does that really work?
Blossom end rot is a common tomato problem that appears as a dark, sunken, leathery spot at the blossom end (bottom) of the fruit. While it looks like a disease, it’s actually a problem caused by a calcium imbalance in the plant.
What Causes Blossom End Rot?
Blossom end rot occurs when the developing fruit doesn’t get enough calcium. However, the issue isn’t usually a lack of calcium in the soil—it’s the plant’s inability to absorb and transport calcium effectively. Several factors contribute to this:
- Inconsistent Watering – Calcium moves through the plant with water. If the soil dries out between watering or if there are periods of heavy rain followed by drought, the plant may not get a steady supply of calcium.
- Excess Nitrogen Fertilizer – Too much nitrogen encourages leafy growth at the expense of fruit development, which can interfere with calcium uptake.
- Soil Imbalance – Acidic soil (low pH) or excessive phosphorus and potassium can block calcium absorption.
- Root Damage – Disturbing the roots during transplanting or cultivating too close to the plant can reduce calcium uptake.
- Container-Grown Tomatoes – Tomatoes in pots dry out faster and need consistent watering to ensure proper calcium absorption.
Will Tums Fix Blossom End Rot?
A popular garden myth suggests that crushing antacid tablets like Tums (which contain calcium carbonate) and adding them to the soil or water will prevent or cure blossom end rot. Unfortunately, this doesn’t work.
- Soil Calcium is Rarely the Issue – Most garden soils already contain enough calcium, and adding more won’t help if the plant can’t take it up properly.
- Calcium Uptake Depends on Watering – Even if Tums added calcium to the soil, it wouldn’t fix the real problem—uneven watering or other environmental factors preventing the plant from using it.
- Spraying Calcium Doesn’t Help – Some gardeners try foliar sprays with calcium, but calcium must be taken up through the roots, not the leaves.
How to Prevent Blossom End Rot
- Water Consistently – Keep soil evenly moist but not soggy. Use mulch to retain moisture.
- Test Your Soil – Check pH and nutrient levels to ensure calcium is available to plants.
- Avoid Excess Nitrogen – Once your tomato plants start setting fruit, choose a fertilizer with a higher middle number (phosphorus) to support fruit production. Avoid fertilizers that are high in nitrogen, as they promote leafy growth instead of fruit.
- Be Gentle with Roots – Avoid disturbing the root system when weeding or transplanting.
- Choose the Right Containers – If growing tomatoes in pots, use large containers that don’t dry out quickly.
Blossom end rot is frustrating, but once you correct the underlying issue—usually inconsistent watering—future tomatoes on the same plant should develop normally.
Happy Gardening
Karen
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