Sunken containers allow you to concentrate the 'best' soil in one location for the vegetables or in this case the cucumber plants. This can save you money. The bottoms are removed or a large portion is cut out of the container to allow the roots to grow beyond the size of the container. This allows the vegetables to grow to full size without worry of root constraints and it allows them to get moisture.
Cucumbers are heavy feeders and should be fed 1 to 2x weekly, based on your choice of fertilizers, once they start producing cucumbers. Cucumbers in my area are prone to soft bodied insect attacks. Growing them vertically not only saves space in your garden but it helps you better manage pests and disease. It is much easier for me to get my soapy water spray on the undersides of the leaves when they grow up a tomato cage.
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