The best time to buy plant fertilizer is when you order your seeds and plants for the garden. That way you have it on hand when you need it. Fertilizer promotes plant growth as well as fruit and flower production. It can also boost your yields of fruits and vegetables. When plants have the nutrients they need, they're more vigorous and better able to withstand insect and disease pressure. One of the most popular organic fertilizers is fish fertilizer. Another natural favorite is White Dutch Clover, which is used to add nitrogen and organic matter to the soil. Shop for all of our plant fertilizers.