My dwarf tomato plant's leaves are getting yellow and wilty from the bottom up

by Karen

Q. I bought my "patio" (dwarf) tomato plant from a store and re-potted it with store-bought potting soil. It seems healthy, and is producing tomatoes, but some leaves are turning yellow, then brown, mainly from the bottom of the plant and initially from the outsides of the leaves in towards the branch... some branches' leaves seem to be affected, while others - particularly higher on the plant - still look robust and green and healthy. One or two of the smaller branches on which the leaves are all brown/grey and dried out (but they don't seem to fall off) are themselves greyed as well. Is there anything I can do to improve this? Could this be from under- or over-watering? The plant is outside on a balcony in the mid-Atlantic region, so it gets some sun and breeze, though not as much as it would in a garden.

A. Some yellowing and browning is natural at the bottom of the plant, simply due to stress. You can pluck off those leaves, discard them, and allow the plant to grow others.

Container tomatoes are rarely over-watered. That's because they are in a limited environment and unable to reach their roots any further than their own home. Under watering is more the norm. If this is the case, you should notice plants wilting during the day, then perking up in the cool evening or early morning.

On a balcony, they may be exposed to more wind than usual. Leaf tips may become browned because of this exposure. And because their environment is so contained, they may be low on nutrients. Are you fertilizing them as well as watering? Leaves on tomatoes in pots can yellow without regular feeding, since roots can't retrieve nutrients from any further than their own little circle.

But the grayed tomato branches are worrisome, presenting the possibility that your plant is the victim of fusarium wilt. First signs are yellowing and wilting on one side of the plant – a leaf, single shoot, branch, or several branches. Yellowing and wilting move up the plant as the fungus spreads. Wilted leaves dry and drop prematurely. The interior of main stem (when split) shows discolored streaks from plugged water-conducting tissue. The exterior of the stem also may show discoloration.

Your plant may also be subject to tomato blight. Compare the three most common types of blight on this page and see if you can make a match.

Good luck and happy gardening!
Your friends at Tomato Dirt