Almost all information about plants has been included with the plants in our free app. So, you don't need to remember it. View the MM app

How to identify and treat tomato blight

Blight - Phytophthora infestans - is a contagious fungal disease that affects tomatoes and potatoes. How do you recognize it and what can you do about it?
Blighted tomatoes

Growing your own tomatoes

Nothing is more fun - or more delicious - than growing your own tomatoes.

You've carefully sown them indoors, pampered them on the windowsill, hardened them off on schedule, and given them the best spot in your garden box. 

Then? Ta da: you then spot the first flowers, green tomatoes, and even see some ripening. You can't believe your luck.  
Flowers and green tomatoes

Help, something's not right

And then. Suddenly you notice that something is wrong. Curly and discolored leaves. Tomatoes with cracks and nasty flecks. That'll bum you out, for sure.

But not every imperfection means that you have to give up on your plant. It might not be the dreaded tomato blight you hear so much about. 

What is tomato blight?

Tomato blight is a fungal disease. Tomatoes and potatoes are very susceptible to it. That's why it's also called potato blight.

It spreads through the air quickly in the summer, especially during wet periods. If it's cold, it spreads even faster. 

How do you identify it?

The first sign of blight is round brown spots on the leaves. The spots can be light green or yellowish around the edges. 
Spots on the leaves
After that, the disease spreads to the main stem and flower stems. You'll notice dark spots that get blacker and blacker: 
Black patches on the stems of a seriously infected tomato plant
Then brownish spots appear on your tomatoes: 
Very sick tomatoes
Eventually all the leaves become wilted and gross, and the whole plant slowly dies. 
A plant consumed by blight

What can you do about it?

Take care of your plants as best you can. Give them an extra tablespoon of nutrients every 5 weeks. If they need extra support, tie them to some bamboo or a trellis.

Remove the suckers from your tall tomatoes the moment you see them. Also, make sure rainwater can drain properly. Cut off a healthy leaf every now and then to give the tomato plant some more room.

Inspect your plants regularly, especially in warm, humid weather and at the end of summer. 

Cut away the affected leaves or the affected parts immediately. Remove any tainted tomatoes. If you do all this, there's a good chance that the plant will still recover. 
Leaves with the first signs of blight
Remove ugly leaves regularly. They're much more susceptible to fungus than healthy leaves. 

After a lot of rain, the remaining leaves will dry off better. Your tomatoe fruits will also ripen faster with fewer leaves blocking their sun. 
All these ugly leaves can be removed

Keep a close eye on your plants

So, you've pruned back all the sickly leaves, but you still need to keep an eye on your tomato plants. The moment you see another spotty leaf, cut the affected piece off.

If you see more signs of blight and notice that it's spread to more parts of your plant, then remove the plant. 

If you don't, the fungus will spread to the MM-Mix and you won't be able to plant any tomatoes in that soil mix for the next few years. 
You can't plant tomatoes or potatoes in this soil mix for the next few years

And pay attention to your surroundings

If there are blighted tomatoes (or potatoes) near your garden, chances are your tomato plants will be next.

So, if you've got neighbors who garden or you're part of a community garden, it's super important that you keep an eye not only on your own tomato plants but also on your neighbors' plants. 
The Eendracht community garden in Appingedam

Not every tomato is equally susceptible

It's good to mention that not every tomato variety is equally susceptible to blight. Just take our cherry tomato: it was bred to be more resilient. Hence the price 😉  
Our super sweet cherry tomatoes stayin' healthy

Save your tomatoes

So, what if you discover that your plant has tomato blight but you've got tomatoes on the vine that aren't quite ripe yet. You don't have to give them up right away. 

Pick the tomatoes that look good and place them on a plate. Add a ripe banana and put a large, clear plastic bag around the whole thing: 
Tomatoes ripening on the windowsill
Place the bowl on a sunny windowsill. Check regularly and remove any affected tomatoes immediately. 

There is a good chance that they will still turn a beautiful bright red in the next few days. 

Good luck! 

Get tips & tricks in your inbox

When you sign up, I’ll send you the top 3 things beginners get wrong. And how you can get it right.

We care about the protection of your data. Read our Privacy Policy

Our perks