Black Spots On Tomatoes Explained…

This disease happens sometimes to your tomatoes, and it’s very frustrating, especially after you’ve put months of work and love into your plants only to see these nasty black dots appear on the bottom of your tomatoes. (see picture below)

Black spots on tomatoes.

It’s called: blossom end rot, or blossom plight. Not to be confused with “year end rot/harvest rot.” That’s a different problem all together.

What begins as a few harmless looking dark spots on the bottom of your tomatoes, can overnight turn into a giant rotting fungus that eats the tomatoes form the inside. And will consume the entire tomato if not removed. Remove the affected tomatoes as soon as you notice sign of this disease.

Often, this will not happen to just 1 tomato on a plant, but many, sometimes even the entire plant, and it can happen very quickly. If you’ve ever had this happen to you, then you know how frustrating this is!

Here’s why it happens:

The experts say it’s because of poor / irregular soil moisture. And I have to say, since I’ve done my own experimenting, it appears to be true.

What does this mean?

When the plant is finally growing fruit, it is at a critical stage, when suddenly the roots get a shock, funky stuff begins to happen to the fruit:

1. If you water your tomatoes not enough, or at times when most of the water evaporates, it could likely cause blossom end rot.

I believe plants are kind of like babies, they like routine, so I stick to a watering routine, usually every morning it’s the first thing I do, plenty of water. I do not believe there is such a thing as “over watering” a tomato plant, they LOVE water.

2. If you grow plants in pots, pay attention, this is critical…

Get BIG pots. The most common problem I see with people growing tomato plants in pots is the pot is just way too small.

A small pot will lead to soil water evaporating quicker as it heats up during the day, which leads to irregular soil moisture. You may water the plant in the morning, as the sun hits the pot at noon, most of the water evaporates and the plant is thirsty for the rest of the day. Dry soil is not good!

How big should your pots be? A good rule of thumb is big enough to fit a basketball in. At least 10 Gallons. And fill it with soil all the way to the top.

Too often people put tomatoes in pots you’d put an orchid in or other flower sized pots, or they put them in big pots but only fill them up half way with soil(which defeats the purpose of the big pot!) The plants grow short and slowly this way. Remember tomatoes are big plants, and they need lots of soil to grow well.

A final thing about pots…

For the same reason, Don’t Use BLACK Pots For Tomatoes!, the color black attracts sun and heats up like crazy, the water in your soil will evaporate in the heat… which leads to problems like these.

The best pots are clay, but they’re expensive. The next best option is white or any other color of plastic. Pots are a big topic which I will write about later.

Above all, the best way to prevent blossom end rot is routine and continuous watering, and being vigilant about soil moisture… once the summer hits, water twice or even three times a day, especially on dry and hot days.

And remember, give your tomatoes lots of love!

That’s it for my weekly tomato tip,

Kacper M. Postawski

Tagged as: Babies, Black Spots On Tomatoes, Blossom End Rot, Critical Stage, Dots, Fungus, Funky Stuff, Giant, Growing Fruit, Growing Tomato Plants, Growing Tomato Plants In Pots, Love, Plight, Pot, Roots, Shock, Soil Moisture, Tomato Plant, Year End