Have you ever gone into your garden and seen unripe tomatoes that fell off the plant, with no idea why it was happening? If so, then you’re not alone. Looking back, I remember seeing at least a few tomatoes drop off some of my plants. This would occur just about every summer. I was curious as to why this happens, so I did some research to figure it out.
So, why are your tomatoes dropping off the plant? Extreme temperatures, lack of water, nutrient deficiencies, pests, or even too much fruit can cause tomatoes to drop off the plant. These factors can cause stress in the plant, leading to weak roots, stunted growth, and dropping tomatoes off the plant.
Looking at other symptoms can usually help you to diagnose exactly what is causing your tomatoes to drop off the plant. Let’s get right into symptoms, causes, treatments, and prevention.
There are several reasons that can explain why your tomatoes drop off the plant. Here is a little more detail on each cause, along with some actions you can take to prevent the problem.
A common problem that can cause tomatoes to drop off the plant is extreme temperatures. In fact, extreme temperatures can even cause problems with pollination, preventing fruit from appearing in the first place.
If your plant is dropping fruit or flowers and has leaves that look wilted or dry and “crispy”, then your plant is likely suffering from extreme temperatures.
The problem could be the time you planted your tomatoes, your climate, or simply a spell of unseasonably hot or cold weather.
The ideal daytime temperature for tomato plants is between 65 and 85 degrees Fahrenheit. At night, the ideal temperature is between 60 and 70 degrees Fahrenheit. As you can imagine, extreme temperatures in either direction will hinder their growth.
If the temperature drops to 55 degrees Fahrenheit or below, the tomato plant will have difficulty in producing energy via photosynthesis. This can cause the plant to drop fruit, since it cannot produce enough energy to support all of the tomatoes to maturity.
You may also see tomatoes or flowers dropping off the plant if the temperature gets up to 90 degrees Fahrenheit or higher.
Luckily, there are some ways to prevent extreme temperatures from damaging your tomato plants.
First, use this map from the U.S. Agricultural Research Service to check your plant hardiness zone (1a through 13b). For instance, in eastern Massachusetts, plant hardiness zones are generally 6a or 6b. Most places in the U.S. will be able to support tomatoes, aside from parts of Alaska, California, and Hawaii.
Once you figure out your plant hardiness zone, be sure to consult a planting schedule, like this one offered by Urban Farmer. This will help you to find the ideal time to plant your tomatoes. You can choose your zone or you can choose your state, and the guide will direct you.
Finally, be sure to choose tomato plant varieties that will do well in your climate. According to Bonnie Plants, heat-tolerant varieties of tomato include Heatmaster, Solar Fire, Summer Set, and Phoenix.
TomatoFest has some cold-tolerant varieties of tomato, which include Alaska, Alicante, and Andes.
If you are growing in a colder climate, you can try building a greenhouse for your plants. If the days are warm, but the nights are cool, then leave the greenhouse door open during the day, and close it in the late afternoon. This will trap enough heat for the plants to get through a cool night, without overheating them during the day.
Lack of Water
A lack of water can also stress your tomato plant and cause it to drop fruit. Drought conditions may damage the root system of your tomato plant. If your tomato plant senses an extended drought, it may decide that it is unable to support all of its fruit, and it will drop some tomatoes to conserve resources.
If your soil seems excessively dry, check out my article on how to treat dry soil.
Too much water can also be a problem for your tomato plant. Frequent, shallow watering can cause root rot and damage the root system. Instead, you should give a good, deep watering on a less frequent schedule.
For more information, check out my article on over watering your plants.
Be sure to water in the morning, when the soil and air are cool and the sun is low. This allows the water to sink into the soil and get to the roots of the plant, instead of evaporating in the sun and heat.
Also, water the plants low, close to the soil. Avoid pouring water all over the plant’s leaves. This may be tempting to do in the hot weather, especially if the leaves are drooping and wilted.
However, pouring water on the leaves is unnecessary, since the plant is perfectly capable of transporting water from its roots to its leaves. Watering the leaves is not only unnecessary, it can also be harmful, especially if you live in a high-humidity area where plant fungus is a common problem.
Any number of nutrient deficiencies can cause problems for your tomato plant. If the plant does not have enough nutrients to support all of the tomatoes, it will drop some of the fruit.
One common sign of nutrient deficiency in tomato plants is chlorosis, or yellow leaves. This is caused by a failure to produce enough chlorophyll (the compound that makes plants green) through photosynthesis.
Some of the more common nutrient deficiencies that cause chlorosis are magnesium and iron.
If the bottom leaves (old growth) turn yellow first, lack of magnesium may be the problem. You can supplement magnesium with Epsom salts (magnesium sulfate). For more information, check out my article on how to treat magnesium deficiency in plants.
If the top leaves (new growth) turn yellow first, lack of iron may be the problem. You can supplement iron with chelated iron or an iron sulfate. For more information, check out my article on how to add iron to your garden soil.
If you want to learn more, check out my article about which nutrient deficiencies cause yellow leaves.
If some of your tomatoes turn brown or black on the bottom, then they are likely suffering from blossom end rot. This is caused by a calcium deficiency, which you can fix by adding lime to the soil. For more information, see my article on how to treat calcium deficiency in plants.
However, before you add any fertilizers or supplements to your soil, make sure to test the soil pH. If the pH is too high or too low, it can make a nutrient unavailable to the plant, even if there is plenty of the nutrient in the soil.
Tomatoes prefer slightly acidic soil, with a pH of 6 to 6.8. If you add a nutrient to the soil when pH is the real problem, you can end up with an excessive amount of one nutrient, which can prevent the plant from absorbing other nutrients.
Another note about nutrients: be sure to employ crop rotation in your garden, to prevent nutrient deficiencies and the spread of disease in your plants. Instead of planting tomatoes in the same place every year, switch their location every other year.
For example, this year you plant tomatoes in the left half of your garden, and beans in the right half. Next year, you plant beans in the left half of your garden, and tomatoes in the right half. This prevents nutrients in the soil from being depleted, since different plants use different levels of nutrients.
There are a few different garden pests that are common foes of gardeners and their tomato plants. One of the more common pests is the aphid.
Aphids are little bugs that feed on sap from new growth. They can be green, white, red, or other colors, and they are not exclusive to tomato plants. They can multiply quickly, stressing or destroying your plants with their sheer numbers.
If you see one branch of a tomato plant infested with aphids, simply prune off the branch. Then, throw the branch away – far from your garden! Otherwise, the aphids can spread to other plants.
For more information, check out my article on how to get rid of aphids.
Another idea is to use artificial or natural pesticides to control aphids. However, you will want to avoid this if you are going for an organic garden.
You can also release ladybugs into your garden, and they will eat the aphids, keeping the problem under control. If you are like me, your ladybug-catching skills are a little rusty. In that case, you can order ladybugs from PlanetNatural.
Another trick to try is companion planting, which means planting your tomatoes along with other plants nearby. These companions are friendly plants that will repel pests to keep themselves, and thus the tomato plants, safe. Some common companion plants for tomatoes are amaranth, basil, garlic, and marigolds.
Crop rotation can also be used to prevent some pests, such as nematodes, from getting established in your garden. As mentioned earlier, crop rotation means that you avoid planting the same type of plant in the same part of your garden two years in a row.
Too Much Fruit
I bet you never thought this would be a problem for tomatoes, or any other plant for that matter! However, too much fruit can be a problem for several reasons.
First, the tomato plant can only support so much fruit at a time. Whether the limiting reactant is water or nutrients, the plant will only be able to provide enough resources to produce a limited amount of healthy, mature fruit.
When a tomato plant starts dropping off some of the fruit, it does so in order to save the rest. Think about it: wouldn’t you rather get 20 nice, healthy, delicious tomatoes than 30 or 40 diseased, disgusting, flavorless ones?
Also, too much fruit can cause damage to the tomato plant. Too much fruit on one branch can cause it to snap or break off entirely. In this case, it is better to lose one or two tomatoes, rather than all of the tomatoes on that branch.
In extreme cases, too many tomatoes can cause the entire plant to fall over, possibly snapping the stem and preventing all of the fruit from ever ripening. If it looks like this might be happening to your plant, take preventative measures.
Pinch off fruit on heavy branches, and provide support to your tomatoes. One way to do this is to drive a tall pole into the ground near the tomato, and tie the tomato to the stake at intervals.
You can also use a cage or trellis to give the tomato something to cling to as it climbs up towards the sun. For more information, check out my article on providing support to tomato plants and my article on why to use a tomato cage.
You can also prune entire branches if they are not producing fruit, since the extra weight can cause your tomato plant to tip over. Just be sure to leave enough branches to shield the tomato plant from intense sunlight.
Hopefully by now, you have a good idea of which of these problems is causing your tomatoes to drop off the plant. You also have a starting point for treating the plants, and ways to prevent the same problem in the future.
Remember that no garden or plant is perfect, and you may sometimes lose a few tomatoes that look healthy otherwise. Remember what Mr. Spock (from the original Star Trek) would say: “The needs of the many outweigh the needs of the few … or the one.”
I hope this article was helpful in diagnosing your problem.