Use a soil conditioner when your soil isn't producing the way you'd like it to or as well as it has in the past. Soil conditioners address these problems by increasing soil pore space, improving air flow, and enabling water to travel easily through the soil. One school of thought suggests that unsuitable fertilizer use can lead to numerous soil problems, while soil conditioners are versatile in addressing specific soil issues. But the great news is that you don't have to choose between fertilizer and soil conditioners as you prep your soil for successful planting; you can use both as needed. Armed with that information, you can make thoughtful choices about fertilizer and soil conditioners.