One tip Lisa asked me to post was the use of pon pon and/or sawdust to conserve moisture. It is placed around the base of the plant and covers the soil, in our case throughout the greenhouse.
Pon Pon is a locally harvested plant that apparently has absorption properties that make it attractive in industrial applications - many people in Ilque and Putenio harvest this by hand, bag it and sell it. There are large open air green houses for drying and cleaning, and the left overs end up on the ground.
A family in our valley harvests pon pon, and they use a drying rack/green house on the property. We get to use the left overs in the vegetable greenhouses and share the vegetables.
It does conserve water and we had quite a bit of success with several plants - cucumber for example - even when it was very dry. Lisa added sawdust to the mix as it was handy.
Here's a link I found that discusses the plant:
SPHAGNUM MAGELLANICUM
http://ponponchiloe.blogspot.com/Here's a pic of Lisa and the vegetables