Ask Mavis – Help! My Tomato Leaves are Turning Yellow

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My Tomato Leaves are Turning Yellow

I have the most amazing readers, and most of the time, it is me learning from you, but every once in awhile, someone sends in a question that I think, “Hey, I bet lots of people would love to know the answer to that.”  So, I am going to try to feature some of your questions and answer them, the best I can.

Shell writes:

Hey Mavis, my tomatoes have yellowing on the leaves…is that a nutrient deficiency? I planted them with egg shells for the calcium. What is also good for them? No bugs, slugs, or other creepy crawlies on them either…I’ve been watching closely.

Good question Shell.  Unfortunately, the answer isn’t super straight-forward.  There could be a couple of different things going on, so you may have to read through these and see if any apply.

Right off the bat, I would want to know the climate in your area when you planted them.  If you plant tomatoes too early, the cold soil and weather will sometimes cause a shock that causes their leaves to yellow.  You could try to use a plastic mulch or black paper to warm the soil the best you can.

Next, if the temperature isn’t the issue.  I would check your soil for two things:  nutrients and pH level.  Check the pH level first.  Tomatoes like a pH level between 5.5-7.5, depending on the variety.  The reason I would check it first is that there is no reason to fertilize if the issue is the soil pH.  You can raise or lower your pH using sulfur {to lower pH} or lime {to raise pH}.  If you are good there, you may need to find an organic fertilizer or high quality compost that will add nitrogen into the soil.

Let’s see, what else?  Are the plants getting enough sunshine.  If just the lower leaves are turning yellow, the top might be shading the plant from getting enough sun.  You can try trimming back some of the top leaves–if your plant is big enough.  {Also, I am assuming you are watering enough, but not so much your tomatoes are constantly sitting in water?}

Finally, if none of those seem to be the issue, you could have a fungal or bacterial issue.  There is a whole host of tomato diseases that each require different types of action, so you may want to take a couple of the leaves to the local nursery and get their opinion if you think a disease or fungus is the problem.

Those are pretty much all of the basic problems that come to mind.  Let me know if any of these help.

Happy Gardening,

~Mavis


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Comments

  1. Another thing to keep in mind is that some plants are sensitive to the water you’re using. I don’t know if tomatoes do this specifically, but softened city water (which may contain chlorine, flourine, and/or sodium may also cause yellowing. Most outdoor spigots should be bypassing the softener, but not always.

  2. Over watching tomatoes can turn leaves yellow — most common in pots.

  3. Hello there,

    I had the same issue and it was caused by a nitrogen deficiency.

  4. Overwatering is the most common cause of this, I think

  5. I think I was over watering and it was slightly cooler than should have been when I first got them in. I live in Dallas, TX. Tomato plants are all in 100% sunshine and the yellowing seems to have improved. I have an heirloom, early girl, random I don’t know what kind, 2 cherry tomatoes and 8 Roma’s. I have them in a raised bed, used your DIY soil with miracle grow fertilizer/food.
    Think my problem was getting them in the ground, right time, but turning on the soaker hose too often for too long at the beginning. I have not used the soaker hose since (waiting for dead summer heat and water restrictions) and have just watered in evenings…or let it rain. So far things seem greatly improved. Will get my soil checked though. I’m doing a square foot garden in the box so have all sorts of things going. Most from seeds…heat of the day is beginning to help things sprout and fast grow. ;)

  6. All good ideas above, and I agree with what Mavis says. Just an add on–if the lower leaves turn yellow and develop brown blotches on their tips, it is probably fusarium wilt, or verticilium wilt. Often these symptoms appear on one side of the leaf and the leaves evetually curl and die. Black spots on the stem near the soil line is also an indication. Improved drainage, pruning for good air circulation, crop rotation and solarizing the soil to sanitize it are all good methods. Be sure to pick off the leaves at the bottom of the plant, so soil doesn’t splash up on the leaves when it rains. Also, avoid watering the leaves.

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