Lime and Fertilizer. A soil test is the best way to determine lime and fertilizer needs. Your county Extension office has information about soil tests. Testing at least every 3 years is a good idea. For most vegetables, the soil pH should be around 6.0 to 6.5. To be effective, the lime must be mixed into the soil before planting. Long-season crops such as tomatoes, cabbage, pepper, okra, and potatoes need more fertilizer than short-season crops. Experience and close observation are the best guides for additional side-dressing.