Why do cucumber leaves turn yellow in a greenhouse and what can be done about it?

Unfortunately, it's not easy to understand why the leaves on these plants start turning yellow, as there are too many possible causes. Therefore, we'll look at several cases to learn how to combat yellowing foliage. There are several effective methods that can help prevent yellowing of the leaves, as well as improve their appearance if the cucumber tops do start to turn yellow. There are various Methods for planting potatoes for an excellent harvest.

Insufficient lighting

If the greenhouse is not properly equipped, the plants may not receive enough natural light, causing their leaves to turn yellow and thin, eventually dropping off. Don't worry if only the lower leaves are dropping and turning yellow, as the dense growth of greenery may not always allow sufficient light to reach the leaves closest to the ground. If yellowing is caused by insufficient light, simply remove the already yellowed leaves, but there shouldn't be many of them.

Too much moisture, or not enough

The reason why cucumber leaves turn yellow in a greenhouse, and how to combat it (video), can be very simple: every plant loves water, but only in moderation. If the soil receives less moisture than it needs, the leaves will begin to turn yellow and dry out. If the humidity is too high, the foliage may even turn yellow.

It's worth noting that underwatering causes plants to grow more soil-bound, which leads to yellowing of leaves and drying out of new fruit. Excess moisture can occur not only with frequent watering but also due to heavy and prolonged rainfall. In this case, roots develop a grill, which spreads not only to the stems but also to the foliage. Watering correctly cucumbers in a polycarbonate greenhouseOn a typical summer day, no more than three times a week; if the weather is dry outside, cucumbers will need daily watering.

Diseases caused by fungal infections

Fungal diseases can cause yellow leaves on cucumber plants and can also affect the future cucumber harvest, so it's important to take steps to eliminate fungi in the soil before planting. The most common fungal infection of cucumbers is fusarium wilt, which affects the foliage and the entire plant as it enters through the roots. Initially, small rust-like spots may appear on the leaves; after a while, all the leaves become covered in these spots, quickly drying out, and falling off.

It's not difficult to spot this disease. If new shoots become wilted and dehydrated, and no improvement is observed after watering, this indicates a fungal disease. Fungal diseases most often affect plants when there is a noticeable temperature change from hot to cold, or if the soil was overly moist due to hot weather. In this case, it's important to quickly identify the cause of yellowing cucumber leaves in the greenhouse and how to combat it yourself, without resorting to chemicals. Cucumber diseases in greenhouses It is necessary to treat it in time, otherwise the plants may die.

The appearance of pests on the site

In some cases, yellowing leaves can indicate the presence of pests in the greenhouse. The most common and dangerous pests for cucumbers are whiteflies and spider mites. These two insects feed on plant sap, and since whiteflies lay large numbers of eggs, the larvae can destroy the crop in just a few days. In this case, it's worth taking preventative measures to eliminate pests from your plot in advance. If this doesn't work, it's recommended to purchase strong pesticides that will save the crop. When insects have just begun to establish themselves on cucumbers, you can also try folk remedies to eliminate these "uninvited guests."

Insufficient amount of nutrients in the soil

This reason for cucumber leaf edges turning yellow in a greenhouse, and how to treat it, is a less common one. However, in some cases, nutrient deficiencies affect the leaves and plants as a whole. For example, when leaf edges begin to turn yellow, this indicates insufficient nitrogen in the soil, as well as a possible potassium deficiency. When the entire leaf turns yellow, and dark green veins appear on the green leaves, this is a clear sign of a manganese or iron deficiency. However, the upper leaves begin to turn yellow if the soil is low in copper. This can be easily corrected by fertilizing the plants with the necessary fertilizers.

The sixth reason will be old age

As cucumbers grow, their leaves begin to turn yellow. This is completely normal as the growth and fruiting period nears its end. However, there are several ways to prolong the life of the vines and improve cucumber yields, which will be discussed later.

We recommend: Fertilizing cucumbers during flowering and fruiting

Prevention of yellowing of leaves

To avoid the hassle of wondering why the lower leaves of greenhouse cucumbers are turning yellow and how to deal with it, it's essential to implement preventative measures to avoid diseases and other problems with greenhouse cucumbers. It's easier to prevent such problems than to fix them later.

The first rule involves proper sowing. Sowing cucumbers in the same spot every year is not recommended, as this only increases the risk of disease. It's also not recommended to plant these crops after squash and pumpkin, as these vegetables can leave behind fungi that will develop rapidly in spring and infect all plants.

The second rule is to maintain watering, as the soil must be consistently and adequately moist. If a gardener only visits the plot on weekends and holidays, mulching is a good idea. Covered beds will remain moist for a long time, as the grass laid on top of the soil prevents water from evaporating. The mown grass will help provide additional nutrients to the roots.

The third rule is proper fertilization of plants. Cucumbers require periodic feeding with mineral substances and organic fertilizers. Herbal infusion is considered one of the most effective fertilizers, and it's easy to make in your kitchen. Before watering the plants, add ten grams of ash to the hole. Crushed ash granules effectively combat harmful insects that attack plants in the garden beds. This substance also helps add potassium to the soil, which plants use for growth and fruiting. You might also be interested to know: What to do if cucumbers don't grow?.

Cucumbers require specialized watering, which is carried out at a specific growth stage (when 3-5 leaves have already appeared on the posts), and repeated every ten days until the fruiting period begins. For the solution, take twenty grams of grated laundry soap, pour it into a liter of warm milk, add exactly thirty drops of pharmaceutical iodine, and mix the mixture with ten liters of clean water.

Other methods can be used for preventative spraying. For example, a special solution can be prepared using a white loaf of bread. First, soak the bread in a bucket of clean water. When the bread is thoroughly soaked in the morning, mash it into a paste and add a full bottle of iodine to the solution. This solution cannot be used in its pure form, so use exactly one liter of the solution per bucket of water and then water the cucumber beds with it. If the gardener repeats this process every fourteen days, they will keep the leaves and buds healthy and green until the fruiting season.

Once June arrives, you can begin the next protection method. For this, you can use an alkaline solution of water and baking soda. You'll need ten liters of clean water and one tablespoon of baking soda. If you water your plants with this solution, fungi won't be able to thrive in the alkaline environment, but your vegetables will thrive. Onion peels also repel pests. If you're wondering why cucumber leaves are turning yellow in a greenhouse and how to combat it (photo), you should learn a recipe for making a solution from onion peels.

To do this, take a liter jar, fill it to the brim with onion peels, pour the resulting amount into a bucket of water, and place it on the stove. Once the mixture boils, turn off the heat, place the lid on the bucket, and let it sit for at least twelve hours. After the allotted time, strain the infusion through a sieve, then dilute it with clean water (2:8). Spray the leaves of the plant on both sides with the resulting mixture, and also water the soil around the cucumbers.

When the leaves have already turned yellow, another solution can help. It's made from whey or kefir. Two liters of the drink are diluted in a bucket of water. To promote fruit set, half a cup of sugar is added to the mixture. The leaves are then sprayed with the resulting solution.