These crops can all be grown in hydro and they do well. Make sure you use a different res for each crop as to ensure proper growing variables for each plant. Maintain heat at night and allow ventilation during day, keeping temps in the 78f range. Make sure res temps stay around 72-75f to prevent mold and other nuisances growing.

These crops are all heavy feeders and drinkers. In hydro, you must remember that the larger the reservoir, the slower variations in ph, tds, temps etc will be. You want that.

You do not mention the type of system you plan on using, but i recommend a diy dwc system for those....large res size and lots and lots of oxygen to the root zone will give you crops that will leave you amazed

I am new to hydro so need to know the following too:

1: Yes, I know these all crops can be grown in hydro but I am talking about to grow them in single
20 x 16 feet greenhouse alltogether at the same time.
For example: If all the four crops can be sown on 1st May 2012....? Plz re-confirm.

Moreover should I maintain greenhouse temp at 78f range for each four crops from seedlings to full maturity or there will be some variables?

2: If the pollen grains (cross pollination) of any kind of vegetable effect any other kind of vegetable resulting in deformed fruit shapes, un-uniformity or show adverse reaction in any way..?
For example cross pollination among tomato, bitter gourd or watermelon?

4: I have an idea to use a fan for a pollination purposes. I want to temporarily place a fan under targeted plant & blow air upwards for 30-60 secs daily that may spread pollen grains in a small scale backyard greenhouse. Please comment.

I have a diagram in a link below & that is self explanatory.

5: Is it necessory to maintain humidity in greenhouse....? I don't want to use eveporationg cooling pads in my greenhouse. If humidity is necessory how much average percentage it should be at for all four crops grown at same time in a single greenhouse...?

Please reply.
Thanks.

Here is a link that might be useful:

MisterK I have some more questions to ask you & they are mentioned above.
Please reply.
I have plan to upload some pictures today.
It will be of my 1st DIY Hydro Vertical Setup Installed on Roof Top.
Hope you will like it.
Cheers.

AZ the temperature ranges K mentions above are ideal. If they vary from those temps, the plants will still grow. the farther they are from those temps the slower, but(in general) the plants will still grow. Good luck keeping a greenhouse with full sun in the summer anywhere near 78ðF
Humidity is not critical for plants. In high heat, a lower humidity is actually better as it allows the plant to transpire more water to keep cool.
Cross pollination normally won't occur across species and even when it does occur within the species, the result is seen in the next generation of plant (from the seeds) not in the fruit of the current season.
you can start all those crops at the same time, but the days to maturity for each may be different.
also, you can grow them all in the same nutrient if they all like the same relative strength of nutrient. Just recognize that in combining them all in the same reservoir, you won't me maximizing the nutrients. some plants will use more of some nutrients than others. the least available needed nutrient is what will restrict the plants growth.