Why Do Tomato Plant Leaves Turn Purple?

Tomatoes are one of the most popular garden vegetables, beloved for their delicious taste and versatility in cooking. However, sometimes tomato plants can develop a purple tint on their leaves, leaving gardeners scratching their heads. In this article, we will explore the reasons why tomato plant leaves turn purple and what you can do to address the issue.

Nutrient Deficiencies

One common reason for purple tomato leaves is a nutrient deficiency. Specifically, plants may lack phosphorus or potassium, both of which are essential for healthy growth. When tomato plants don’t receive enough of these nutrients, they may develop purple coloration, especially on the lower leaves.

To address this issue, you can fertilize your tomato plants with a balanced fertilizer that contains both phosphorus and potassium. Be sure to follow the instructions carefully, as over-fertilization can actually make the problem worse.

Cold Temperatures

Cold temperatures can also cause tomato leaves to turn purple. This typically happens when plants are exposed to temperatures below 55°F (12°C). When this occurs, the plant’s ability to absorb phosphorus and other nutrients is compromised, which can lead to leaf discoloration.

If you suspect cold temperatures are the cause of your purple tomato leaves, try covering your plants with a lightweight fabric or plastic sheeting when temperatures drop. This will protect them from the cold and prevent further damage.

Plant Genetics

In some cases, purple tomato leaves may be the result of the plant’s genetics. Certain tomato varieties, such as ‘Indigo Rose,’ are bred to have purple coloration in their fruit and leaves. If you are growing one of these varieties, there is no need for alarm.

However, if your tomato plants are not a naturally purple variety, genetics may still play a role in leaf discoloration. Some plants simply have a genetic predisposition to develop purple leaves, even if all other conditions are ideal. Unfortunately, there is not much you can do to prevent this if it is the case.

Environmental Stress

Finally, environmental stress can also cause tomato plants to develop purple leaves. This can include high levels of sun exposure, wind, or drought. When plants are under stress, they may not be able to absorb nutrients or water as efficiently, which can lead to leaf discoloration.

To combat environmental stress, make sure your tomato plants are getting adequate water and are not exposed to excessive sunlight or wind. You can also consider using shade cloth or other protective measures to reduce stress on your plants.

Conclusion

Tomato plants can be finicky, and sometimes it can be difficult to determine why they are not thriving. However, by understanding the reasons why tomato plant leaves turn purple, you can take steps to address the issue and help your plants flourish.

If you have tried all of the above solutions and your tomato plants continue to develop purple leaves, you may want to consult with a gardening expert or your local cooperative extension office to determine if there are any other underlying issues that need to be addressed.