What’s Wrong with my Tomato?


What’s Happening to my Tomatoes?
by Rob Sproule


We’ve all been there. Your tomato plants are growing just as they should and you begin to have visions of juicy salads, delicious salsa and beefy beefsteak sandwiches dancing in your head. Your mouth waters as you watch the fruit form and then, as it ripens, something happens.

When the fruit is affected, the culprit is usually due to the growing conditions rather than a virus. While that’s good news in the sense that it won’t spread like wildfire, it means that you’ll need to re-think your watering, fertilizing, and planting habits.


Blossom-End Rot:

This is the scourge of tomato growers everywhere! The fruit, ripe or unripe, develops a sunken, rotten “bottom” that can be tiny or cover up to half the fruit. It turns brown, hardens to leather and ruins the fruit.

Neither a fungus nor a disease, Blossom-End rot is a growing issue. The culprit is a lack of calcium, either because there’s not enough provided or because it’s unavailable for the plant to access.

Sprinkle a handful of blender-pulverized, dried eggshells in the hole when you plant for an extra calcium boost. You can also use bone meal or garden lime. Don’t plant too early; cold soil makes calcium inaccessible to immature root systems.

Tomatoes need regular fertilizer with a high middle number. A high first number (nitrogen) will limit fruit production and make it harder (via chemistry that I don’t understand) for the roots to access calcium.

Add a generous layer of organic mulch (straw, wood mulch, whatever) to keep moisture in the soil. Inconsistent watering is another major culprit of blossom-end rot.



If the bottom of your ripening tomato starts to pucker inwards until its sunken enough for scar tissue to form in the cavity, you’ve been “cat faced.” The term comes because the indented scar makes it look like a pushed-in Persian cat face.

Catfacing develops when temperatures drop below 10-15 Celsius for a couple days during flowering. The female organs don’t develop properly in the cold and, as a result, the flower can’t be pollinated effectively. The deformity starts at the blossom end of the fruit (the bottom) and can become so large that it ruins the fruit.

High nitrogen fertilizers (the first number) promote cat facing as well as exposure to 2-4 D (“Killez”). As a rule of thumb, avoid spraying weed killers anywhere around your edible plants. Even if they aren’t fruiting, they will absorb the toxins in to their system.


Growth Cracks:

A very common affliction that all comes down to watering. When tomato plants dry out the flesh toughens up. Follow a dry spell with a deluge of water, whether from a hose or the sky, and the flesh cracks when the stem, which is like a faucet, pumps more water into the fruit than the tough flesh can expand to accommodate.

Growth cracks occur from the stem and can either be concentric (circular cracks, happening near the stem, that occur near the stem), or radial (straight lined cracks extending down from the stem). You’ll need to pick cracked fruit quickly before it rots. Cut out the crack and rest is edible.

The secret to avoiding cracks is consistent watering. It’s harder than it sounds, especially when tomato vines get large enough to suck up a gallon a day our dry, summer heat. Spreading a generous layer of organic mulch (wood mulch or straw) will level out the peaks and valleys of your watering cycle and help keep a consistent flow of moisture through the stem.


Read through our Growing Guides for tips to enrich your garden! 

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