Beans and legumes draw up nitrogen from the soil as well as drawing it from the atmosphere. Beans rarely need to be fertilized, they do it all by themselves. On the other hand cucumbers are heavy feeders and require a lot of fertilizer. Grown together the beans fertilize the cucumbers.
Experience has taught me that Some climbing beans and peas do not fare well together as the competition for space and the vines intertwining and strangling each other out outweighs the advantages. Use of a variety of bean / legume that doesn't produce excessive vines. Smaller bean plants, bush beans should be placed in such a fashion so as to avoid being over-shaded by the cucumbers.
Radish - Radishes repel rust flies and cucumber beetles to some extent. Cucumbers and radishes both do best in full sun and well drained soil so there is no conflict in this issue.
"Sow two or three radishes among your cucumbers, and let them grow as long as they will, even blossoming and going to seed. You may trap cucumber beetles by filling shallow containers about three-quarters full of water into which some cooking oil has been poured." Carrots Love Tomatoes- L.Riotte
Lettuce and Cucumber make a nice salad and they work together in the garden also. Cucumber plants are space-hogs, so try not to over shade the lettuce.
Onions, Garlic, and other Alliums serve cucumbers well as they repel many of the pests which infest cucumbers.
Marigold, Nasturtium, Savory are all advantageously planted near cucumber for their pest deterring properties. Nasturtium in particular repels squash bugs and cucumber beetles two major curcubit pests.
Growing Cucumbers Hydroponic Cucumbers Cucumber Diseases
Cucumber Mosaic Virus Bacterial Wilt Cucumber Insects
Red Hmong Cucumber Designer Cucumbers Sikkim Cucumber
Lemon Cucumber Crystal Apple Cucumber White Wonder Cucumber