Hydroponic/cold frame?

by Melinda
(Meadville, PA,USA)

Well, the last two years I have been on a few missions trips to Northwest Mexico in the mountains of the Chihuahua State. The mission group is ministering to the Tarhumara and Pima Indians. There is very little farmable soil in these regions and quite frankly, people still die from starvation there.

I am putting up a greenhouse to grow vege's for them in the mountains and have some questions.
Because they get their water from a small creek and from springs that run down the mountain there are dry seasons when there's not enough rain. That fact and the fact of poor soil has pushed my thinking towards growing with hydroponics.

Some other obstacles are possibly no eletricity and an altitude of 6,000 ft.

So, I am thinking of putting up a cold frame (20x60), covering with two layers of plastic and a blower fan to inflate the layers (there will be electric at this greenhouse).

Secondly, I want to be able to roll up the sides for cooling during the day (have a shade cloth/energy blanket also). So far so good but will it be problematic for the plants growing in the nutrient solution (hydroponics)? And will having the sides rolled up be enough to take care of pollination? Or will it attract too many pests?

The weather in the mountains can vary with 50 degree nights and 85-90 degree days. The humidity is lower there but they have a rainy season for 6 weeks late June to early August where the nights are 50 degree and the days in the 60s. It usally will rain hard in the afternoon and then stop. Just was wondering if any one has any thoughts or suggestions? I'm all ears!!

--------------------------------------
Answer from Stella/Simon:

First of all, we applaud you in your efforts to help those folks who live in a depressed area, with poor growing conditions. The practice of hydroponics is growing not only in the US, but also in third world countries as a means to help feed the people. Hydroponics requires much less water to function and support crops than traditional soil-based gardens, and you can improvise by using recycled materials and locally available supplies.

That being said, I think your project will be a challenge, and may require a few failed attempts until you find what works for that region. If you have electricity, then you could try any of the simpler methods, like ebb & flow or a top-drip setup.

Lettuce rafts are super easy to set up and run, and can grow many different small crops, particularly lettuces, small peppers or herbs. Rafts are often seen in photos of hydroponics projects in undeveloped countries.

Honestly, the weather conditions sound ideal there. Hydroponics works best in milder temps and lower humidity. Temps above 80 will require fans and shade cloth to keep it cool. You might find yourself fighting off the bugs, though. Rotenone or neem oil would be some of the safest pesticides to use to save a crop.

As far as specific plans for your project, there's so many ways you could go. Check out this page of links to some foreign projects in progress: http://www.cityfarmer.org/subhydro.html

We wish you the best of luck in your worthwhile project.
Hope this helps!

***Do you have any ideas for Melinda's Mexican project? Then please join in and leave your thoughts and suggestions below. Help and be helped in the Forums!