I use Register with Ministry of Labour on the phone to make Farmer my Sims job. Then earn money from the crops and produce. If you have Get to Work you can make a retail lot to sell their products and use Canning to make preserves to sell. So the farm is their actual job and it can be more profitable than many careers. I add some fishing too and other harvestables as well as the farm crops. I've got one Farmer with a garden centre and had another one that had a jam shop.
It does get busy but if you add in the various aspirations and switch between them to gain more reward points it helps your Sim get everything done. So I get the Seldom Sleepy reward, Carefree, Steel Bladder, etc as soon as I can to help them out. You can also hire a professional gardener to help out with plants. While they're busy I have mine eating fruit from their inventory instead of cooking too, to save time.
If you befriend the local rabbits by gifting them with produce, they will also help you with the gardening. It takes a while though as they can be a bit cantankerous!🐰