If you are a big fan of Mexican dishes, you will probably love growing your own tomatillos in your garden. These fruits are sometimes called husk tomatoes, and are closely related to tomato plants. However, they do not taste like tomatoes! Instead, tomatillos are a mixture of sweet, tart, and fruity – a bit like a blend of lemons and herbs.
Growing your own tomatillos can be very rewarding, but if their leaves start turning yellow and looking unhealthy, your joy might turn to frustration very quickly! If you are seeking answers as to why your tomatillo leaves are turning yellow, you are on the right page. We have listed below the possible reasons your plant might suddenly look pale and sad, as well as how you can correct the issue.
Causes of tomatillo leaves turning yellow
1. Overwatering and poor drainage
Too much watering is the leading cause of yellowing tomatillo leaves – and, unfortunately, this watering mistake tends to be quite common among inexperienced growers! Aside from yellowing, overwatered tomatillo plants are also at high risk of developing root rot and fungal diseases.
So, how often should you water tomatillo plants?
When it comes to watering your tomatillo plants, the rule of thumb is fairly straightforward – water only when the top layers of soil have had time to dry out after the last watering. Under normal weather conditions, about an inch of water per week should suffice.
2. Drought and underwatering
Excessively dry soil and long periods of neglect can also cause your tomatillo’s leaves to yellow. Although these crops are moderately drought-tolerant, they certainly cannot survive without adequate hydration.
Like all plants, tomatillos need water to perform the metabolic processes required for growth and fruit production. Water is also essential to maintain their vigor and turgidity. Hence, if your plants are deprived of water, they will droop and start suffering from leaf discolorations due to extreme dehydration. If this goes on for too long, your tomatillo plants will eventually die.
Usually, underwatering is easier to solve than overwatering. If you think the yellow leaves are due to underwatering, just giving your plants a good soak should ensure a full recovery.
3. Lighting issues
Lighting conditions can make or break your success when it comes to growing any plant including tomatillos. Too much heat and sunlight exposure can easily burn their delicate leaves. Conversely, if you keep them in the shade for too long, the lack of sunlight can inhibit their photosynthesis, resulting in pale and unhealthy-looking foliage.
Hence, an optimal level of light is key to keeping their leaves green and healthy. Make sure to select an appropriate location where these nightshade plants can get about six hours of sunlight every day.
4. Lack of soil nutrients
The naturally-occurring organic matter in the soil should serve as a reservoir of macronutrients essential for plants to flourish. In reality, though, not all gardeners are lucky enough to own a backyard with nutrient-rich soil. This means that you will probably need to use fertilizer to keep your garden healthy – even more so if your plants are grown in pots.
But how do you know if your tomatillo plants are nutrient-deprived? Depending on the type of nutrient deficiency, some of the tell-tale signs of undernourished tomatillo plants are as follows:
- Magnesium deficiency: Tomatillo plants with this deficiency tend to display yellow leaves which later progress into brown, necrotic spots. A magnesium deficiency can be fixed by adding Epsom salts to the soil during the autumn or winter seasons. Once the soil is replenished, you can expect healthier and bushier plants in the next growing season.
- Nitrogen deficiency: A lack of nitrogen can cause tomatillo leaves to become pale and yellow. That is because nitrogen is an essential nutrient responsible for the green color of the leaves. You might also notice that the affected plant has stiff stems and petioles, dropping foliage, and reduced growth. Adding a nitrogen-rich fertilizer or decomposed manure should help you fix this issue.
- Potassium deficiency: One of the obvious signs of potassium deficiency in tomatillo plants is yellowing leaves, especially around the edges. Although the fruit might retain its green color at the base of the stalk, the leaves often become dull and dry. A quick fix for this issue is to feed the plants with a potassium-rich fertilizer.
- Sulfur deficiency: Similar to other nutrient deficiencies, a lack of sulfur can cause chlorosis (or yellowing leaves) in tomatillo plants. At first, you might notice the upper leaves turning pale and yellow, but this unsightly discoloration will soon begin to affect the lower leaves, too, until the entire tomatillo plant becomes yellow. The best thing you can do to solve this deficiency is to enrich the soil with fertilizer or compounds rich in sulfur. Composted mushroom is also an excellent option if you prefer organic fertilizers.
5. Downy mildew
Downy mildew is a plant disease that can greatly affect the yield and quality of your tomatillos. At first, it might be a bit tricky to recognize the disease, especially for inexperienced gardeners. Some of the signs you should look out for are:
- Discolored blotches that appear on the upper surface of the leaves.
- Shriveling and yellowing or browning of the foliage.
- Mold-like growth that appears on the underside of the leaves.
- Loss of vigor in affected plants.
Unfortunately, there are no effective fungicides available to completely eradicate this disease. The best thing you can do is establish preventative measures to protect your tomatillos from getting infected in the first place.
Here are some tips to prevent downy mildew:
- Avoid dense planting, in order to promote air circulation in your garden.
- Do not water your plants in the evening. Instead, water them early in the morning so that the leaves have enough time to dry during the course of the day.
- Discard any plants that are affected by the disease. Never reuse them in your compost bin or any other area of your garden.
- Make it a habit to disinfect your gardening tools after using them.
6. Psyllid infestation
Psyllids, also known as jumping plant lice, are plant-feeding insects that suck the sap from your tomatillos’ leaves and cause them to turn yellow. Aside from competing with the plant for nutrients, these pests also leave a honeydew substance on the leaves that promotes the growth of sooty mold.
Organic options like neem oil or insecticidal soaps will usually solve this problem. Simply spray the liquid mixture while the insects are feeding on the leaves. For severe infestations, we recommend using stronger, long-lasting insecticides that contain Bifenthrin to kill the pests and prevent them from coming back.
Can yellow tomatillo leaves become green again?
Plants often reveal their unhealthy state through the yellowing of their leaves. If your tomatillo leaves are turning yellow, it is obviously a sign of distress which might be caused by improper watering, fungal and pest issues, or inadequate sunlight. Unfortunately, once the leaves have turned yellow, they will not regain their green color again.
Should I remove the yellow leaves?
If the entire leaf has turned yellow, you can trim it off so that the plant can focus its resources on the other, healthier leaves. Removing the yellow leaves will also help encourage new growth and keep your tomatillo plants in their best shape.
Some growers also snip off a few yellow leaves simply because they find them unappealing. This is perfectly okay, as long as you are only cutting the dead leaves.
How to fix yellowing leaves on tomatillo plants
Fixing tomatillo plants with yellow leaves might require some effort and patience, depending on the severity of the issue. In most cases, plants can recover quickly if the problem is corrected at an early stage, whether this is related to improper watering or other unfavorable growing conditions.
Early diagnosis of a pest infestation is also critical. As mentioned before, organic solutions such as neem oil and insecticidal soaps often work wonders to kill pests and prevent them from coming back. However, insecticides that contain stronger chemicals might be your only option for severe infestations.
For more serious issues like fungal infections, rescuing a dying plant might be more challenging. Often, saving the affected plant might be an impractical approach, and the best thing you can do is remove the plant and start all over again.
Conclusion
Plant leaves that are turning yellow are usually a red flag, so you should never take this symptom lightly! Thankfully, you can usually revive a yellowing plant, provided you are able to diagnose the issue at an early stage. Make sure to correct your watering habits, and also check for nutritional deficiencies.
Prevention is better than cure, so try to keep your tomatillos healthy at all times to prevent unwanted pest infestations and fungal diseases. However, should these occur, early action is crucial. With a bit of patience and loving care, your tomatillo plants should recover in no time!
Image: istockphoto.com / Petra Richli