Question
My cucumber and zucchini plants look great and have lots of flowers but don't produce any vegetables, what's wrong?

Answer
Hi Terry,

How long have your plants been flowering?  If it has only been a few weeks then I encourage you to be patient.  Cucurbits such as cucumber and squash will often produce male flowers for a few weeks before producing any female flowers.  I would suggest you look closely to make sure you have male and female flowers present.  The male flowers usually have straight stem whereas the females have a swollen area at the base of the flower.  There is a picture a slight ways down the page at the following link:
http://www.omafra.gov.on.ca/english/crops/facts/87-043.htm
There are other differences with floral parts, but usually swelling or no swelling is a pretty good indicator.

If you find that you do not have female flowers, just wait a little longer.  If the plants have received too much nitrogen fertilizer, sometimes they do not produce many female flowers.  It's the plants way of saying that it's happy and there's no need to make progeny.  Some cucurbits will not produce female flowers if they are not getting the right amount of water or if the plants are under too much shade.

The last reason for no fruit--no bees.  Cucurbits require insects for pollination.  Many plants are self pollinated or wind pollinated, but not cukes and zucchini.  They need a bee to visit the male flowers and transfer pollen to the female flowers.  So, if you do not observe any bee activity then this could be the problem.  Plants such as tomatoes can self pollinate although they do sometimes benefit from insect pollination.

If you don't see any bees and you have male and female flowers, you can be the pollinator.  All you have to do is take a Qtip and wipe it inside the male flower to collect some pollen.  You will probably see a yellow color on the cotton.  Then, insert the Qtip into the female flower and wiggle it around.  This should pollinate the flowers.  You may want to repeat a few times and hit several different flowers to increase your odds.

Good luck!