Purple Tomato Leaves: Why Are My Tomato Leaves Turning Purple?

Tomato Leaves turning purple is a cause for concern. The most common reason this occurs is a phosphorus deficiency. Tomatoes are heavy phosphorus feeders.

The most common and logical reason for a phosphorus deficiency is simply that there is not adequate phosphorus in the soil, but it is not the only reason. At times there may well be enough phosphorous in the soil but the plants are unable to absorb it, an ‘uptake’ issue.

Symptoms Phosphorous Deficiency Tomato Plants

Phosphorus Deficiency Causes Purple Leaves

Phosphorus deficiency is sometimes confused with nitrogen deficiency, it is uncommon, but does occur in areas with excessive rainfall or poor soil. Soil such as heavy clay or chalk soils.

Cold weather can cause a deficiency which is generally temporal. Symptoms include stunted growth, foliage that turns blue/green or Purple. The undersides of tomato leaves, as well as the veins and stems, sometimes turn purplish.

Older growth leaves are affected initially, followed by new growth foliage. See Also: Plant Nutrient Deficiencies.

Under cooler growing conditions tomato plants are sometimes temporarily hampered in their ability to absorb and use nutrients. Temperatures around or below 60 degrees will create this issue.

Generally assuming your purple tomato foliage is related to cool weather, it will rectify itself as the plants mature and the weather warms.

Do not overwater as it tends to exasperate the situation.

If your plants have not been subjected to cooler temperature and still exhibit symptoms of phosphorous deficiency than your soil is probably lacking in that essential element.

Phosphorous rich soil amendments of bone meal or Organic Miracle Grow are best as they are more easily and rapidly absorbed by the plants than mineral sources of phosphorous.

Miracle-Gro Performance Organics All Purpose Plant Nutrition, 1 lb. - All Natural Plant Food for Vegetables, Flowers & Herbs - Apply Every 7 Days for Best Results - Feedsup to 200 sq.'
  • Miracle-Gro Performance Organics All Purpose Plant Nutrition feeds plants instantly
  • Apply easily with the Miracle-Gro Performance Organics Garden Feeder or your watering can
  • Enhanced with micronutrients to deliver high performance results

Other Reasons Tomato Plants will turn purple

Psyllids are small flying insects, basically sap-sucking plant lice. They are easy to spot as they are usually present in large numbers. Shaking the plant at times will send a cloud of them into the air. They inject a toxin into the plants which causes the purple discoloration.

The earliest symptoms of a Psyllid infestation is a slight yellowing and/or purple discoloration of the upper leaves. Lower leaves tend to curl slightly upward.

Under a severe infestation, the entire top of the plant changes to a reddish-purple and sometimes yellowish-green. If you are dealing with a psyllid infestation, try using neem oil to control the situation.

Curly top virus is another reason. It is caused by Leaf Hoppers, symptoms include a purplish color of the veins and leaf undersides as well as chlorosis, yellowing, and distortion of some leaves.

Read: Additional Tomato Plant Diseases and Troubleshooting

Recap

The most common reason for your tomato planting turning purple is a phosphorus deficiency. There are two reasons this may be happening:

  1. Not enough phosphorus in the soil.
  2. The plants are unable to absorb the phosphorus in the soil.

When trying to troubleshoot purple leaves on your tomato plants, run through these three possibilities.

  1. Phosphorus deficiency.
  2. Psyllids infestation.
  3. Curly top virus.

Now you know what to look for. Go out and remedy the situation and try to be proactive in preventing your tomato plants from turning purple in the future.

Smart Hydroponics Growing System for Indoor Gargen,E-SUPEREGROW Hydroponic Gardening System with Smart Timer Pump,Large Self Watering Planter with 60" Trellis for Cucumber Tomato Herd Pepper Mint
  • 1️⃣【Smart Hydroponic System】Our hydroponic gardening system can grow super as pictures. It is not an indoor hydroponic grow concept, but also a real growing miracle. Built-in pump with timer for good water circulation to increasing oxygen to support super growth. Self-watering and waterless auto remind makes planting much easier. Put the unit where could get direct sunshine, you could grow all year indoor,season-free. it's a good gardening gifts for women, patent and kids.
  • 2️⃣【Easy to Use】Compared with pipes or other products, our indoor hydroponic system is smart and easy. Simple assembly and disassembly, just add the water and ferti when it reminds you, no need to take much care, anyone can be a good gardener even the beginners.Easy-Clean-Safe-Convenient.Suitable for anywhere indoor where could get direct sunshine(it is important, or 48W LED grow light) home, kitchen, closed balcony, office, hotel, and restaurant, would work for big pots of Microgreens as well.
  • 3️⃣【Excellent Water Circulation】The hydroponic kit with double-layer structure design, the water tank and the planting groove are separated. Which is conducive to air circulation and makes the unit to be a larger water circulation system, provides more oxygen to plants, and makes them grow better. Compare with the single-layer product, you don't need to worry about damage the pump and water circulation when the roots are too large. Ideal for vegetables, melons and fruit.