Of the plants that I grow, the ones that grow better than in soil are Peppers, Lettuces and Strawberries. Those 3 are pretty much all that I will grow hydroponically in future.
There are others that also grow very well, such as onions which grow to a huge size, but as I don't grow for the show bench it is rather pointless growing football sized onions for the kitchen. Carrots also grow well and with no root fly damage, but you are restricted to the ball type ones. French beans grow well too, but in my set up I can only grow the dwarf types and I much prefer the climbing variety. I would imagine the dwarf Runner beans would grow equally well, but I never tried them. Cucumbers grow well too but as they are climbing plants, I have the same height problem that I have with beans
Tomatoes are an exception. They grow exceptionally well hydroponically, and I have grown many different varieties over the years and comparing them against the same varieties growing in soil. The hydroponic ones had more fruit per plant and bigger fruit than the soil grown ones, but in every case the hydroponic ones had little or no flavour in comparison to their soil grown siblings.
That's probably the reason most shop bought tomatoes are pretty bland as I would imagine nearly all commercially grown tomatoes are hydroponic now.
Out of pure interest I did grow other things just to see ...
Peas grew well, as did broad beans, melons were OK, radishes and spring onions also did well.
I grew mangetout peas and they grew very differently to soil grown ones. They grew well, produced masses of pods which were all picked. Then a few days later it started to sprout new growth and a couple of weeks later was loaded with flowers again. This happened 3 times in all and might have continued but it was late in the year and by the third time it was nearly winter.
Of those above, only radishes were worth the bother of growing hydroponically although I just might experiment with mangetout next year and start them off earlier this time.
Plants that didn't do well for one reason or another were Cauliflowers which do really well if you persevere with making sure the calcium levels are right, but in reality that's too much trouble when all the other types of plants in the pipes are perfectly OK without the extra faffing about.
Calabrese are weird in that they grow well, produce nice sized heads, but never make any side shoots. Soil grown ones go on producing side shoots for weeks or even months after the main head is cut, so are much more productive.
Overall the down side of growing hydroponically is the small extra cost of the electricity to run a pump three times a day for about 10 minutes, plus the extra cost of buying the nutrient. (I haven't got to grips yet with making my own)
Another point is it's not organic, although I did dabble with making an organic nutrient with compost, seaweed and comfrey, something I shall continue experimenting as I would like to have the nutrient as pure activated compost tea.
The upside is that it just about runs itself without supervision. I have to top up the nutrient every 3 weeks and empty and refill the tank every 9 weeks, other than that just pick the produce. No weeding involved and all at a comfortable waist height.
So, this winter I will dismantle the pipe in the polytunnel and reclaim 20 sq ft of growing area and I might relocate it in the big greenhouse, making it a three pipe system, but it's becoming a question as to what will I grow in it. There's only so many peppers, lettuce and strawberries that two people can eat.
Sorry for the rambling epistle.
