Most gardeners will experience some problems when growing tomatoes. They can be finicky about water, sun, and soil and that means a healthy crop is dependent on the weather and other conditions that are out of your control. However, when problems arise, knowing what you are dealing with will increase your success growing tomatoes. Ideally, we can prevent them before they start, but don't despair, you can also take steps to correct these common tomato problems while the plants are growing. The juicy, tangy, full flavor of that first ripe tomato is always worth the effort.
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Tomatoes That Turn Soft and Black (Blossom End Rot)
Blossom end rot is not a disease and most likely the result of a calcium deficiency caused by irregular watering and a fluctuation in water levels. It may be tempting to try to correct this problem with supplements and fertilizers, but your first step is to correct the underlying moisture issue.
Plants rely on water to carry nutrients, like calcium, up from the roots throughout the plant. When a tomato plant receives insufficient water, the nutrients will first go to the foliage and may not make it all the way to the fruits. That is why it's important that your plants get at least 1 inch of water a week, every week. You can't make up for a couple of dry weeks by finally giving your plants a deep watering. The damage is done by then.
Roma type tomatoes may be more susceptible to blossom end rot in part due to their growing habit. These are the more oval-shaped tomatoes popular in Italian cuisine. A determinate type, the vines grow rapidly and bear large clusters of fruit all at once over a 2 to 3 week period. Check the blossom ends of these tomatoes when they are still small. If you see a black spot, remove and discard the tomato. This takes some stress off the plant allowing it to put energy back into healthy vines and fruits. The good news is, if you stick to good garden practices, your tomato plant will likely recover and begin to produce healthy fruit.
Besides insufficient or irregular water, blossom end rot can also be exacerbated by a handful of problems including these:
- Excessive nitrogen fertilizer will cause a lot of leafy grow and divert nutrients away from the fruits.
- Too much salt in the soil will inhibit the uptake of water. High levels of salt are often caused by excessive use of synthetic fertilizers.
- Root damage also restricts the uptake of water. Roots can be damaged by animals or cultivating.
- Soil pH can be either too high or too low for the tomato plants to access the nutrients in the soil. Tomatoes prefer a soil pH around 6.5.
While you cannot save the fruits that already have blossom end rot, you can salvage the rest of the season by being vigilant about watering, mulching around the plants to conserve moisture, and correcting any other problems.
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Ripening Tomatoes That Crack
Otherwise healthy looking tomatoes split open before they're even fully ripened. What happened, how can you stop it from happening, and are they still okay to eat?
Tomatoes tend to crack when the amount of water they receive fluctuates. Often when tomatoes experience a prolonged dry spell, we try to make up for it with excessive watering. This causes the pulp inside the tomato to hold the water and swell faster than the outside of the tomato can stretch. When that happens, the outside of the tomato splits open, causing cracks.
The good news is that the tomatoes are fine otherwise and perfectly edible. However, you will need to use them immediately, because the cracks will start to develop mold.
To prevent cracking, make sure your tomato plants are getting regular water. That can be hard to do when there is excessive rain, but you can still moderate things by watering weekly when the weather is dry. A 4–6-inch layer of mulch will help keep the soil around the roots moist, further moderating the moisture level in the plants.
If cracking is a major problem, look for varieties that are labeled as crack resistant. Some good ones to try include Celebrity, Pruden’s Purple, and Sun Gold.
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Never Fully Ripe Tomatoes (Green Shoulders)
You can wait and wait some more, but some tomatoes are never going to fully change to red. This is not the same as that frustrating wait for green tomatoes to ripen at the end of the season. Tomato "Green Shoulders" is a condition in which the majority of the tomato ripens, but the area near the stem remains stubbornly green and hard. There's a similar condition called "Yellow Shoulders", which occurs when production of the naturally occurring chemical lycopene slows down. Lycopene is the substance that gives fruits and vegetables their red color.
These conditions are a bit more complicated than the two tomato problems discussed above. Sometimes it's just the type of tomato you're growing and sometimes the weather and sunlight play a hand. To prevent the problem, be sure your tomatoes have a bit of shade and pick the tomatoes early if you're experiencing intense heat.
Picking a little early and setting the tomato in a sunny window may encourage more uniform ripening. While green shoulders are disappointing, the portion of the tomato that has fully ripened should still be delicious and is fully edible. Just slice off the green portion and no one will be the wiser.
Tomatoes may require some extra care and attention in the garden. A good staking system, soaker hoses, planting deep and inspecting the crop regularly are all good garden practices to bring a good harvest. The tomato is probably the most versatile fruit from the home garden to the table. Once you've tasted your first, you will want to make tomatoes a staple in your garden every year.
Why Are My Tomatoes Cracking? Iowa State University Extension
A Visual Guide - Problems of Tomato Fruit. Missouri Botanical Garden