This is a satellite view of a rooftop in Mumbai. This is our farmland.
For this project — we’ll grow only spinach in that farmland.
Mom Nature’s rules for Spinach
One plant of spinach takes 30 days to be ready for harvest. It grows from seed to harvest and takes 30 days to reach the stage when it can be eaten.
Using Aquaponics, I have been able to touch 100 gms worth of spinach from one netpot.
What is a netpot -
The netpot  is a plastic cup that has space for water to flow through.
The netpot can be filled with any medium like coco peat, clay balls or even rock gravel (which is what I use).
The plant sits inside this netpot. And the roots grab onto this medium.
On our project rooftop — we will install 5000 netpots — meaning we will harvest 500kgs of spinach in a month.
[ 5000 netpots x 100 gms per month ]
…this is 500 kgs coming to us on day #30. For the rest of the 29 days — no spinach has arrived. And after harvest — it’ll be another 29 days before the next 500kgs will arrive.
SCALING THE PRODUCTION
We’ll replicate this setup on 30 rooftops in Mumbai.
But we don’t sow seeds in all the rooftops together. We sequentially stagger the seeding cycle — 1 rooftop each day.
Sequence of Events
For the first 29 days of this project — nothing happens.
The first harvest from Rooftop #1 arrives at day #30.
Harvest 2 from Rooftop #2 arrives on day #31
Harvest 3 from rooftop #3 arrives on day #32
…and so on…
Till day #30.
Now we’re clocking 500kgs of spinach everyday. At market rate of INR200 per kg — this generates INR1L of revenue per day.
This is Maths for spinach — some food like celery is selling at INR50 per stem ! The customer premium for non-poison food is all a bonus. Also bonus — a chance of maybe making this revenue tax free.
Now do this for the 10 cities across the country — Cities like Delhi, Kolkata, Ahmedabad, Pune, Nashik, Bengaluru, Chennai, Hyderabad, Vijayawada, etc.
What’s this 30 day cycle?
This is called a ‘Crop Cycle’  and every plant has its own crop cycle.
Spinach takes 30 days. Fenugreek takes 20–24 days. Cucumbers will grow in their vegetative stage for about 40 days before they will bear fruit for another 20–30 days — so a total of about 70 days of crop cycle.
There are indeterminate varieties of plants which can go through a crop cycle many times over — meaning they can continue to supply fruits for as long as a few years. Cherry tomatoes are one of the best examples of such a plant.
— — — — — — — — — — — PART 2 — — — — — — — — — — — — — — — — —
Now that we’re generating INR1L per month in Mumbai — let’s quickly run through the operation costs.
There are 3 operational expenses :
- Power Bills
- System Maintenance
- Water bills
- Farmer Salary
- Crop Harvest Team
- Nutrient Additives
- Fish food
Here’s a question for you — can you tell me 3 Big challenges with Aquaponics on a rooftop?
Drop a comment below with your questions.