PRODUCTION

Tomato Issues & How To Fix Them


June 3, 2023

There are several issues that can come up with tomatoes. As far as where they stand in the garden, they could be considered a bit of a diva. They like regular watering – not too much, not too little. They like warm weather – not too hot, not too cold. And they like their soil just right – not too alkaline, not too base. With a little forethought and planning, you can make sure your tomatoes grow healthy and produce a ton of fruit.

Golden retriever dog laying in garden with basket of fresh tomatoes

Before we talk about problems, get a soil test. If you’ve read any other articles I’ve written you know this is a mantra for me. You cannot give your plants what they need if you don’t know what it is. It’s cheap and easy and you can do it yourself. So…test your soil.

luster leaf Rapitest 1601 Soil Test Kit

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Tomato with disease causing a black spot

Blossom End Rot

Your tomatoes look great…growing strong. And then you notice a black scab growing on the bottom of your fruit where the blossom used to be. It spreads, creating a depression in the fruit. The dreaded blossom end rot (cue scary music). This issue has several causes – both soil and weather related. And unfortunately, by the time you see it in action, it’s hard to stop.

With that said, here are some preventative measures you can take. Test your soil. Blossom end rot is caused by too little calcium or a problem with pH. Lime or bone meal are great additives to boost calcium. Lime can help with pH. but in order for your plant to absorb calcium, make sure your tomatoes are being watered on a regular basis. It’s not good enough to water every once in a while. Even if you aren’t giving them a lot, water consistently.

In addition to healing your soil, you can use a foliar spray to help give your plant an immediate dose of calcium chloride early in the season. This spray is easy for plants to absorb and can help protect tomatoes from the beginning.

Gardner & Bloome, Bone Meal, 4 lb

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Bonide, Rot-Stop Tomato Blossom End Rot Spray, 32 oz

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close up of tomato blossoms

Blossom Drop

Another problem related to weather is blossom drop. Like the name suggests, this is when the tomato loses its blossoms before setting fruit. Remember when I told you tomatoes are divas? Well, they like their weather to stay between 55 degrees and 75 degrees all the time (wouldn’t we all). In protest of anything outside their expectations, the blossoms drop.

In addition to weather, lack of water or issues with nitrogen in the soil (remember that soil test?) can also contribute to blossom drop. Too little or too much nitrogen can be fixed several ways. While fertilizer can boost nitrogen for the moment, planting companion plants like beans or clover can help fix nitrogen in the soil long term. Just be careful not to crowd out your tomatoes. They like friends, but not too many.

It stands to reason if flowers aren’t pollinated, they don’t have much else to do and will drop. I like to surround my tomatoes with a ring of marigolds, but any bright flower will attract the right insects. Marigolds have an added bonus of smelling gross and deterring unwanted bugs.

Another solution is to use a fruit set or blossom set spray. Spray it directly on the flowers. This hormone is harmless to insects – specifically pollinators. The spray doesn’t pollinate the flowers, but it helps the blossoms to hold on until they are pollinated and able to set fruit. I use this every year and have had very good luck with it.

Bonide, Ready-to-Use Tomato & Blossom Set Spray, 8 oz

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Children picking fresh tomatoes from garden

Lack of Fruit

You’ve got the blossoms but you don’t get very many tomatoes. Or the tomatoes you do get are tasteless and small. What do you think you should do? Test your soil. Poor fruit set is often related to too much nitrogen. While people think of nitrogen as a great fertilizer (and it is in certain circumstances), nitrogen encourages the plant to grow up and leaf out. So while it’s growing beautiful leaves, it doesn’t spend much energy on fruit. You can fix this by adjusting the balance with mulch or planting in a different soil and letting the affected soil rest.

G&B Organics, Soil Building Conditioner, 3 cu. ft.

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Diseases

Most diseases have pretty obvious outward signs. If you see browning or spots, you may be facing a disease. It’s difficult to know immediately if the disease is fungal, bacterial, or viral so finding ways to attack all three is a good idea. Again, I turn to neem oil for its antifungal properties. It doesn’t cure things, but it certainly slows the disease down.

Damaged tomatoes on a branch in a greenhouse

Blight

Blight is one of the more common ones. You will notice round spots on the leaves that continue to grow in size, killing them as it goes. It will also consume fruit in the same way, often destroying the entire crop. When faced with blight, the best solution is to remove and destroy the plant. But neem oil can slow it down, and you can still eat the fruit by cutting around the blight.

Septoria leaf spot on tomato. damaged by disease and pests of tomato leaves

Leaf Spot

Leaf spot is another common disease. Most of the time, you’ll see it on the older, lower leaves. Removing these leaves to lessen spread helps. Leaf spot hangs on over winter in debris from the plant, so make sure you get rid of any leaves you clip.

Copper fungicide will help curb the problem but the best bet is to take preventative measures by cleaning up your garden at the end of the season.

Bonide, Captain Jack's Copper Fungicide Spray, 32 oz

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Herbivores

A larger pest you may fight is deer and other herbivores. A well-built fence is a fantastic protection, as is a greenhouse. But you can also make your tomatoes less appetizing by treating them with a repellent spray. Neem oil also tends to deter them and is less smelly than repellent sprays which are made to smell bad.

Bonide, Repels-All Animal Repellent, 32 oz

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Toddler helping mother in garden by watering tomato plants

Weather

Weather is really the only factor we cannot change. And in the Pacific Northwest, we know there can be temperature swings and unexpected showers during the summer growing months. But there are a few things we can do to mitigate weather issues.

Probably the easiest way to control the climate for your plants is to grow them in a greenhouse. This gives you almost complete control over the amount of water, heat, and sun your plants get. You can achieve this with shade cloth and consistent watering in a traditional garden, but there’s not much you can do about heat.

Cracking on the growing tomato

Fruit cracking

One of the most frustrating issues comes with two weather problems – first it’s hot and dry, then it rains a lot. This makes the tomato absorb lots of water all at once and its swollen body cracks out of its skin…kind of like when you’re thirsty so you drink too much and think you’re going to explode, but you crack instead. The only real solution is to be consistent with watering so your plant doesn’t gorge itself when it rains.

Sunscald

We all get excited when the sun comes out. This is true for tomatoes as well. But just like us, they can sunburn. While you can’t coat them with sunscreen, you can protect them from the hottest rays of the day by giving them shade. It seems counterintuitive to protect a sun-loving plant from the sun, but I’m talking about giving them some shade. Leave some leaves on the plant – maybe more than you think you should when pruning. If the days are really hot, get some shade cloth and create some cover for your tomatoes. I’ve even seen a neighbor stick an umbrella in the ground to shade her tomatoes. Whatever works.

Sun Guard Poly Mesh UV Protection Shade Cloth Tarp 10'x12'

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girl in pink dress point at green tomato on plant in greenhouse

While there are other challenges our tomatoes face, these are the most common. And if you look at them, we can combat them all with a little pre-planning. Test your soil. Water consistently. Catch diseases early. And watch the weather. With those tools in your gardener’s pocket, those divas should give you some beautiful fruit.

Tomato Variety Guide

Find the match for your tomato patch.


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ROBYN ROGERS, THE AUTHOR OF THIS BLOG IS LOCATED ON THE KITSAP PENINSULA IN WASHINGTON AND HER ADVICE IS CONSISTENT WITH THE CLIMATE THERE.