@Tossilah when you want to do organic farming it means you will apply organically formulated products in raising your crops e.g tomatoes in every step from nursery to marketing. To be precise on tomatoes, I will begin from
site selection and planting- ensure you do proper crop rotation thereby avoiding planting tomatoes subsequently in same plot similarly do not follow family related crops e.g eggplant, potatoes on same plot this will help you as a farmer great deal as a farmer to manage diseases and pests hence reduce cost of production. On planting prepare land early enough probably a month before transplanting to ensure soil aeration improved, your crops benefit from decomposition of organic materials that were buried at ploughing
(Nitrogen flush). Additionally look for well decomposed compost manure or farm yard manure preferably from chicken droppings or goat because of high nitrogen composition they have and also well balance in relation to other nutrients. You can also go for bio- industrial fertilizers .(
4tons/ acre or 10tons/ ha compost manure/ FYM) . In tomatoes
Blossom end rot disease is a common problem the disease has two major causes, irregular watering and lack of calcium in the soil. The first one you will manage by watering regularly especially when the crop is at flowering and fruit formation stage while for the latter add organic calcium rich substances at planting these may be obtained from dolomite lime, oysters cells or crushed egg cells. For pets you will look for those formulated from pyrethrine or do a home made Neem plant extract mixed with chilies