Beans germinate very quickly, generally in less than 2 weeks sometmes in as little as 5 - 7 days. This varies dependent on the variety, seed quality and environmental factors.
Once your seeds have germinated into a start with at least 2 true leaves, it should be placed in the hydroponic setup. Spacing of course varies among different varieties.Bush beans are typically planted 2-4" apart, pole beans are generally spaced roughly 4-6" apart.
The consensus seems to be that ebb and flo systems work best for most types of beans, but realistically any system will work. Wicking, drip and even aeroponic systems. Currently I have been growing modest amounts with a small aquaponic setup rigged up with a guppy tank. See: Fish Tank Aquaponics
Beans are a self-pollinating plant so hand pollination shant be needed.
A loose grow media is best for hydroponic bean production. Perlite-Vermiculite blend or expanded Clay pebbles both have proven advantages
Perlite has a neutral pH and will not affect the alkalinity or acidity of your solution.It is inexpensive and reusable.It is very porous and has excellent wicking action, meaning that it will absorb and draw up liquids via capillary action.
Expanded clay pebbles, clay aggregate or whatever designation you prefer to use enables a balance of moisture, food and air to your plants.
Root rot is eliminated by the space between the pebbles allowing all-important oxygen to get to the roots.
Beans grown naturally, in soil that is, prefer full sunlight. More sunlight equates to a hardier heftier harvest. 12 - 13 hours a day is just dandy. They will grow with more or even less but additional problems work their way into the equations at that point. Too much light for too long is not a good idea.
Plants also need a night cycle during which they will absorb carbon dioxide aka carbon fixation. Beans are no exception so try not to exceed the 12 - 13 hour light requirement by too much. Also See - Grow Lights
The optimal temperature for the widest range of beans is 70 to 80 degrees Fahrenheit during the day cycle and roughly 65 to 70 degrees during the night cycle. Temperatures below 60 or above 90 F. will have adverse effects on plant development and pod growth.
That's air temperature, the nutrient solution temperature is slightly different. See: Hydroponic Temperature
One reason beans are so easily grown hydroponically is that they require only relatively small amounts of nutrients.
Beans will actually pull nitrogen from the air but they can also benefit from trace minerals such as chlorine, cobalt, molybdenum, zinc, boron, manganese, iron and copper. If you're not a hydroponic chemist, a pre mixed nutrient blend is advisable and please remember that the job of the company that makes the nutrients, in addition to producing a quality product is to get you to use as much as possible. You can safely assume that any recommendations found on the nutrient label can be cut down a tad.
Beans grown hydroponically will usually produce more rapidly that those grown conventionally. Conventionally the norm is about 60 days, which of course varies dependent on variety and environmental factors. Hydroponically, in a controlled environment, you can anticipate shaving about 7 - 10 days off that time.
A continual harvest can be ensured by placing new plants in the hydroponic setup about every two weeks.
Pests and Diseases
Grown indoors in a hydroponic setup pests should not be a major issue. They are not however unheard of. Fungus Gnats, Aphids, Mites, White flies at times find their way in. Grown outdoors you can expect to encounter nuisance insects such as bean beetles, aphids, mites basically any pests that would attack the plants grown conventionally.