Tomato plants are relatively easy to grow in your kitchen garden, but why do they turn yellow?The yellowing of tomato plants and their leaves is a very common problem which you may face over the growing period. Beware though, quick fixes can sometimes make it worse.Tomatoes are scientifically categorized as berries and are commonly used as vegetables, and can be consumed raw or cooked. Tomato seeds germinate in 10-14 days, but the time taken to germinate is dependent on temperature. Seeds will take longer to germinate in cool temperatures and will be faster in warm temperatures. Planting tomatoes is also economical since one seed packet will contain dozens of seeds, and the quantity of produce is very good if grown well. Tomatoes are green when raw and bright red with they’re ripe. The tomato plant can grow 3-4 ft (0.9-1.2 m) tall and 10-30 lb (4.5-13.6 kg), or 20-90 tomatoes., depending on the size. Tomatoes grow well in a warm climate with a lot of sun. The seeds are usually planted in late spring to early summer and are harvested two to three months later. When your tomato plant is growing, you may notice yellowing leaves. This is nothing to worry about in most cases; yellowing can be caused by natural processes, fault in watering, or other diseases like fungal disease, blossom end rot, Fusarium wilt, and Verticillium wilt. Gardeners often try to use quick fixes to get rid of yellowing leaves on tomato plants, but the best plan of action is to observe the yellowing leaves and know the growth stage of the plant before taking any action. Yellowing caused by different problems and diseases has specific telltale signs which will tell you exactly what the problem is. After observing the symptoms, the gardener should take an educated decision to better the plants’ health.If this article helped you in combatting tomato plant leaves turning yellow, make sure you check out other related articles like why do tomato leaves curl and why do your ears pop.Why do tomato plants turn yellow?Yellow leaves can be caused by multiple reasons, each of which has its own telltale signs and fixes. The causes of yellowing in tomato plants are overwatering, underwatering, lack of nutrients, transplant shock, diseases, and the natural cycle.The yellowing leaves on tomato plants at the bottom of the plant are not a cause for concern. Those leaves are the first leaves after germination and are not considered true leaves. These tomato leaves start turning yellow after the seedling is around 6 in (15 cm) tall. It is a part of the development process of the plant and natural for the older leaves to turn yellow and fall off. It is easy to identify them as they will also look different. Unlike true leaves, these older leaves will be thin, long, pointed, and will lack the hair-like fuzz.Watering problems like overwatering and underwatering also cause the leaves to turn yellow. Gardeners often get over-enthusiastic about caring for their plants and end up overwatering them. When a tomato plant in a garden is overwatered, the air pockets in the soil get filled with oxygen, and the plant’s roots are not able to access any oxygen. The roots can also start to rot due to the lack of air and excess moisture in the soil. This leads to the leaves turning yellow and eventually falling off. An easy fix is to show it sun more often if possible so that the soil can dry up or cut back on watering the plant for a day or two. If the problem still persists after a few days, root rot could be the culprit. It is hard to bring the plant back to health at this point, and it’s best to start growing another plant. Although rarer, tomato plant leaves can turn yellow when underwatered too. The leaves become pale yellow from the edges and dry up. Simply start watering the plant more often or increase the quantity of water.Soil compaction is another culprit which leads to tomato leaves turning yellow. Soil compaction is when the soil doesn’t have air pockets. When the soil around the plants is often walked upon it may press down the soil, filling up air pockets near the roots. Instead, grow the tomato plant in a raised platform, large pot, or avoid walking near the tomato plants.When the seedlings are moved from their warm environment to the soil outside, they may undergo transplant shock in the initial few days. Transplant shock causes the leaves to turn yellow from the lower leaves of the plant. In such cases, there isn’t much you can do. Wait for the plant to adjust to its new surroundings and if the problem still persists try to recognize the symptoms for other causes of yellowing. If the new leaves sprouting from the top of the plant are a healthy green, you can gently remove the loose yellow lower leaves so that the plant can focus on the new growth.There are various diseases that can affect the growth of a tomato plant and make leaves turn yellow. Different diseases affect the plant in different ways; judging by the pattern of wilting and yellowing leaves, you can identify the problem plaguing your plant. Early blight is caused by a fungus in the soil and appears in the bottom leaves of the plant. Initially, a pale yellow spot will appear on the leaf, which will turn into a dark brown spot. Eventually, due to early blight, the entire leaf will turn yellow and fall off. Septoria leaf spot is another fungal disease that causes the tomato leaves to develop large brown spots on them, on yellow patches. The fungus can also spread onto the plant stem and cause more damage if left untreated. There are three types of wilts that plague tomato plants and damage their leaves. Fusarium wilt spreads from the soil and infects the roots of the plant. The disease disrupts the water transportation from the roots to the stem and leaves. The entire plant begins to wilt, and the leaves droop, even though there is no fault in watering. Due to this disease, plant leaves will begin turning yellow from the top of the plant and will eventually fall off and die. Verticillium wilt symptoms are similar to that of early blight disease and Septoria leaf spot; yellow and brown spots develop on the lower leaves, and the veins turn brown. The yellow spots turn brown, and the lower leaves fall off. Compared to the other wilts like verticillium wilt and Fusarium wilt, bacterial wilt disease is rarer. A bacteria found in moist sandy soils causes the leaves to wilt and the plant to die. The disease can begin affecting the plant when it is transplanted but will show symptoms much later in the season.Nitrogen deficiency in the soil can cause yellowing in tomato plants. The soil needs to have the right ratios and quantity of macro and micronutrients. The lack of macronutrient nitrogen is the most common nutrient deficiency which can cause problems in the growth of the plant. Nitrogen from the soil plays a vital role in the overall growth of the plant and the production of new leaves. Nitrogen deficiency symptoms are stunted growth, yellowing of old leaves, the poor growth rate for new leaves, fruit, etc. The lack of micronutrients in the soil could affect the production of chlorophyll, the green pigment in leaves. Thus, the tomato leaves turn yellow while the vein and stem remain bright green.At the end of the season, older leaves turn yellow and fall off. This is a part of their natural life cycle. The entire tomato plant is getting rid of old leaves and flowers, fruit, and new leaves will begin to grow, flowers, and fruit. The right season for tomatoes will begin in late spring to early summer and end by late summer, after around two to three months.How to fix the yellow leaves on tomato plants?If the yellow leaves on tomato plants are the first two leaves at the bottom of the plant, do not worry. Those are not true leaves and are actually cotyledons. Those leaves will die early in the growth of the plant.Yellow plant leaves caused by overwatering can be revived by simply not watering the plants for some time, especially if the damage was caught early. If overwatering has reached the extent where the root has started to rot, you have to carefully remove the plant from the garden soil or pot entirely, cut off the rotten portions and replant in fresh soil. This might not be enough to save your plant, so it is best to start growing another one. If the plant is getting underwatered, start watering it more often. Make sure it is watered every time the topsoil is dry.To fix soil compaction, simply aerate the soil near the roots using your hands. Be careful not to touch the roots directly as that could damage the entire plant. Gardening tools can also be used to aerate the soil. When transplanting the plant into a pot, make sure the soil, compost, and fertilizer mix are well aerated. Yellow tomato plants’ leaves caused by transplant shock need to be given a few days to get used to the change in surroundings and temperature, during which they should not be moved or bothered.If the tomato plant has a disease like early blight or fungus, it gets a little harder to stop the tomato leaves from turning yellow. If the tomato plant is suffering from early blight or septoria leaf spot, remove the infected leaf, dispose of it without letting it come in contact with the other plants, and treat the entire plant with a fungicide, as per instruction. If you notice any of the wilts on your tomato leaves turning yellow, throw the plants immediately. There is no cure or treatment for wilts, and they can spread to the other plants in the garden. Use good quality fertilizers and practice crop rotation to avoid these diseases.For overriding the damage and yellow tomato leaves caused by deficiency of nitrogen, micro, and macronutrients, the garden soil has to be supplemented with the correct quantities of all essential nutrients for plants in the fertilizer. Garden tomatoes are the healthiest when they can absorb all the nutrients they require from the fertilizer. The nitrogen in the fertilizer, garden soil, and compost ratio in the final potting mix is also very important. Fixing the diet of the tomato plant may not turn the already yellow tomato leaves but can make sure that all future leaves are healthy and green.The most important thing to remember when you are trying to remedy the yellow leaves of your plant is to stay calm. If you panic over the health of your plant babies, you might end up making an ill-informed and wrong decision. You must be very careful in observing the symptoms; panicked quick fixes will never be correct and can cause more harm to the plants. Also, remember that plant growth is not magic; the plant may take a while to show results, positive or negative, to the treatment or remedy they are undergoing. If you choose to move from one treatment to another, make sure you give enough time to the plant to adjust so that it is not negatively affected by the sudden changes.How to water correctly?While there are no fixed rules as to how much water a tomato plant needs, it is best to know the signs of overwatering and underwatering and how to combat it effectively. Amateur gardeners often feel that the plant needs water every day. This is not true in most cases if the garden is in a very hot and sunny area where the soil will dry out very fast. Gardeners should water the tomato plants if the first 1-2 in (2.5-5 cm) of soil is dry. Water should be poured on the roots and not the leaves. If the leaves are wet and most for too long, they might rot. The water must be poured gently so that the soil does not get eroded near the roots. Seeds before termination and seedlings need to be watered even more carefully. It’s best to use a low-pressure spray to ensure they don’t get overwatered. If the tomato plant is growing in a pot, make sure it has proper holes for drainage, and the compost and soil have high porosity.Here at Kidadl, we have carefully created lots of interesting family-friendly facts for everyone to enjoy! If you liked our suggestions for why do tomato plants turn yellow then why not take a look at why do cells divide, or why do leaves fall.
Tomato plants are relatively easy to grow in your kitchen garden, but why do they turn yellow?
