There are many reasons why greenhouse cucumbers are wilting and dying. It can be due to poor watering, bad soil, cold, pests etc. To understand what causes cucumbers to wilt let’s look at the structure of the plant.
Herbaceous plants (non-woody) stay upright because of water pressure also known as turgor pressure. Plants absorb water with the roots and loose it in transpiration through the leaves. When more water is lost rather than absorbed via the roots, leaves and stems no longer stay upright and begin to wilt.
The most common cause of wilting cucumbers in greenhouse is inadequate watering. That includes dryness and overwatering, both can be results of poor drainage. If the soil inside greenhouse is heavy clay or lacks organic matter, it will not drain water properly and moisture will accumulate around cucumber plant roots, leading to wilting and dying.
#1 Underwatering
It is totally normal for cucumbers to looks perfectly fine in the morning and a little bit droopy in the evening. That is because the plant is thirsty. Also, it is very common that cucumbers are wilting in the afternoon on a hot day in a greenhouse. However, if you have noticed that cucumbers are wilting in the morning, it is a sing of a problem.
If you fail to water cucumber plants sufficiently during the growing season, it can soon lead to wilting of the leaves. Underwatered plant leaves are turning brown, wilt and look dying. Cucumber leaves that feel dry and crispy to touch are wilting and dying from underwatering. Although most plants recover quickly if you water them promptly, prolonged underwatering will lead to the death of plant leaves.
#2 Overwatering
Overwatering is the most usual reason why plants are dying in a heated greenhouse in winter. Cucumber plant leaves start to soften and become limp to the touch. When the leaves droop, many owners think that plant is short of water and start to water it more. As a result, plants are wilting and dying.
How do you water cucumber plants in greenhouse?
The best way to water cucumbers plants is little and often. As a rule of thumb, you should keep soil in greenhouse thoroughly moist at all times but never soggy. Be extra careful not to overwater cucumber plants in the first 2 to 3 weeks after planting out. Avoid waterlogging.
Overwatering and underwatering do not necessarily mean that you are giving too much or too little water. Sometimes it can be a result of problems with soil. Let’s have a look how composition of the soil can affect drainage.
#3 Poor Soil
Heavy clay soil or soil that lacks organic matter (compost) will not drain water properly and it will accumulate water around cucumber plant roots, leading to wilting and dying. On the other hand, sandy soil cannot hold either water or nutrients very well, making plants short of water.
Always check the soil before planting. You can refer to the best greenhouse soil guide to determine what type of soil you have in your structure. Keep in mind that garden soil alone is not suitable for greenhouse growing. This type of soil compacts and can kill tender plant roots.
#4 Low Temperature
Cucumbers are cold-sensitive plants, so the temperature after planting out should be no lower than 55° – 60°F. Most of the time the sudden fluctuation in temperature rather than cold air causes wilting and dying of cucumber plants in a greenhouse.
Although thermometer tells you precise readings of the temperature inside the greenhouse, you need to keep in mind that soil temperature might be different. So, you must take daily soil temperature readings too. Do not plant cucumbers until soil temperature reaches 65°F. If the temperature falls below minimum, cucumber plant leaves will yellow and wilt.
#5 Hot and Dry Air
That is a very common issue in summer. So it is very important to ventilate your greenhouse. If the temperate is too high it bakes the soil, as a result, plant roots are going to die. In some cases it can be a problem in winter if a plant needs cool resting period when light intensity is low.
Also, cucumber plants can start wilting in a greenhouse if exposed to the direct rays of midsummer sun. That is why it is very important to choose an appropriate location for a greenhouse. Moreover, you can use shade cloth to reduce the amount of harmful UV light.
#6 Pests
There are two groups of pests that target cucumber plants – Squash Bugs also known as Anasa tristis and Squash Vine Borer (Melitta curcurbitae). Although these pests mainly attack vine crops like squash and pumpkin, they target cucumber plants during summer months.
Squash bugs suck the sap out of the leaves which causes cucumber plant to wilt. The symptoms of squash bugs are yellow spots on the leaves that later can turn brown.
Squash Vine Borers lay eggs at the base of cucumber vines. Then larvae emerge from these eggs and feed on the vines disturbing the passage of water to the leaves. As a result, cucumber leaves are wilting and dying.
#7 Diseases
Apart from pests, there are number of plant diseases that are known collectively as wilt and these diseases can cause wilting and dying of cucumber plants. Viruses, bacteria and fungi cause these diseases. The most common disease is Bacterial Wilt.
Bacterial Wilt (Erwinia tracheiphila)
Bacterium Erwinia tracheiphila causes cucumber plants to wilt and die rapidly. You can recognize the infected plants by dark green color. Striped or spotted cucumber beetles spread the pathogen from plant to plant. To prevent the disease you need to control the population of beetles on plants.
A sure way to check if your plant is affected by cucumber beetles is to slice off the stem of wilting plant. Then you need to squeeze out some sap. If the sap is stretchy and slimy, plant is suffering from bacterial wilt. Unfortunately, there is no treatment available.
– Why cucumber plants are wilting in greenhouse and not indoors?
It is very common for cucumber plants to wilt after transplanting them into greenhouse from indoors. Cucumber plants are very delicate meaning that their vascular tissue can break easily. If you damaged roots or stem when transplanting cucumber plants, it can lead to them wilting and dying.
That is why you should directly plant seeds of cucumber plants where you want them to grow. Take a look at how to grow seeds directly in the ground. However, you can start cucumber seeds indoors in the peat pellets so you can just transplant pellets with seedling directly into soil.
