Newbie from Mumbai | New Gardeners | Commercial Hydroponics farming in India

Hi all. I started vegetable gardening in my backyard very recently. I succeeded in growing bitter gourd, bottle gourd and my chilli plants are doing nicely. However, I failed with the tomatoes, capsicum, spinach, radish. My herb garden includes spearmint, peppermint, basil, purple basil, stevia, a variety of chives; but I am unable to grow Cilantro.
I want to grow lavender, chamomile to boost the pollinating insect like bees; but I was unable to germinate seeds of both.
Recently I have grown seedlings of cucumber and cauliflower as well as I have some potatoes planted.
I stay in the same location from my birth and I can recall my dad and granddad growing lots of veggies in the monsoons when I was a child. My grand dad is no more and my dad has since then diverted to growing roses and other flowering plants.
I believe that a garden should be productive; though the peace I get out of getting my hands dirty in soil is reason enuf to keep me continuing. I have a plethora of doubts and the collective information of the fabulous gardeners here will surely help me. Thanks to all in advance.
Nilesh.