So I assume you manually edit the date you last watered and fertilized every time you do it?
I think the only tricky thing here is you basically have 2 tasks in one row. I would construct a JSON object like this for each row:
{
"Task name": "Water plant X",
"Date": "Add date here"
},
{
"Task name": "Fertilize plant X",
"Date": "Add date here"
}
Then join all rows together to form a joined JSON, separated by a comma and a newline character.
Add a template column to wrap it inside square brackets.
[
J
]
With J being the template I show in the first step.
Then, add a new table, add a lot of rows, like 100, to cover just in case.
Follow the steps here to create a row index.
Then, you can use a query JSON column with JSONata to query out each element in that JSON array, using the index.
Use that table in your calendar component.